Designing high power targets with computational fluid dynamics (CFD)
Covrig, S. D. [Thomas Jefferson National Laboratory, Newport News, VA 23606 (United States)
2013-11-07T23:59:59.000Z
High power liquid hydrogen (LH2) targets, up to 850 W, have been widely used at Jefferson Lab for the 6 GeV physics program. The typical luminosity loss of a 20 cm long LH2 target was 20% for a beam current of 100 ?A rastered on a square of side 2 mm on the target. The 35 cm long, 2500 W LH2 target for the Qweak experiment had a luminosity loss of 0.8% at 180 ?A beam rastered on a square of side 4 mm at the target. The Qweak target was the highest power liquid hydrogen target in the world and with the lowest noise figure. The Qweak target was the first one designed with CFD at Jefferson Lab. A CFD facility is being established at Jefferson Lab to design, build and test a new generation of low noise high power targets.
Dr. Chenn Zhou
2008-10-15T23:59:59.000Z
Pulverized coal injection (PCI) into the blast furnace (BF) has been recognized as an effective way to decrease the coke and total energy consumption along with minimization of environmental impacts. However, increasing the amount of coal injected into the BF is currently limited by the lack of knowledge of some issues related to the process. It is therefore important to understand the complex physical and chemical phenomena in the PCI process. Due to the difficulty in attaining trus BF measurements, Computational fluid dynamics (CFD) modeling has been identified as a useful technology to provide such knowledge. CFD simulation is powerful for providing detailed information on flow properties and performing parametric studies for process design and optimization. In this project, comprehensive 3-D CFD models have been developed to simulate the PCI process under actual furnace conditions. These models provide raceway size and flow property distributions. The results have provided guidance for optimizing the PCI process.
Chapman, Clark R.
With faster processors and better numerical techniques, computational fluid dynamics (CFD) tools have revolutionized engineering design and optimization-- limiting expensive experimentation and Engineering Division (GED) at Southwest Research InstituteÂ® (SwRIÂ®) has extensive experience and capabilities
Lee, S.Y.
1997-06-01T23:59:59.000Z
One of the interim storage configurations being considered for aluminum-clad foreign research reactor fuel, such as the Material and Testing Reactor (MTR) design, is in a dry storage facility. To support design studies of storage options, a computational and experimental program was conducted at the Savannah River Site (SRS). The objective was to develop computational fluid dynamics (CFD) models which would be benchmarked using data obtained from a full scale heat transfer experiment conducted in the SRS Experimental Thermal Fluids Laboratory. The current work documents the CFD approach and presents comparison of results with experimental data. CFDS-FLOW3D (version 3.3) CFD code has been used to model the 3-dimensional convective velocity and temperature distributions within a single dry storage canister of MTR fuel elements. For the present analysis, the Boussinesq approximation was used for the consideration of buoyancy-driven natural convection. Comparison of the CFD code can be used to predict reasonably accurate flow and thermal behavior of a typical foreign research reactor fuel stored in a dry storage facility.
Application of computational fluid dynamics (CFD) to nuclear applications.
Brewster, R. A.; Jonnavithula, S.; Rizwan-Uddin; Rock, D. T.; Weber, D. P.; Wei, T. Y. C.
1999-02-08T23:59:59.000Z
Detailed analysis of a quarter channel was performed using VIPRE and CFX. Results show that VIPRE and CFX agree closely in both cross-sectionally averaged axial temperature and cross-sectionally averaged axial velocity profiles. Detailed temperature distributions in the radial direction over 1mm from the clad surface towards the center of the channel were calculated using CFX, showing significant local variation. This information can be used for example, to determine if this temperature will lead to bubble nucleation. Quarter subassembly calculations were made with both VIPRE and STAR-CD. Comparison between the solutions show that the two codes yield very similar solutions under comparable conditions. However, the STAR-CD CFD calculation provides the analyst with much more detailed flow and temperature distributions than can be predicted by a one-dimensional code such as VIPRE. In addition, a 60 million cell one-eighth reactor core calculation was made using STAR-CD. This analysis showed the importance of accurately predicting the flow and temperature fields in all assemblies simultaneously with modern parallel processing technology, practical turnaround for these types of calculation can be obtained.
European Conference on Computational Fluid Dynamics ECCOMAS CFD 2006
Barr, Al
aluminum tubes due to the passage of ethylene-oxygen detonation waves is presented. 1 INTRODUCTION The Center for Simulation of Dynamic Response of Materials at the California In- stitute of Technology has reliably with such a "weakly coupled" method, when the evolving interface geometry and velocities
JACKSON VL
2011-08-31T23:59:59.000Z
The primary purpose of the tank mixing and sampling demonstration program is to mitigate the technical risks associated with the ability of the Hanford tank farm delivery and celtification systems to measure and deliver a uniformly mixed high-level waste (HLW) feed to the Waste Treatment and Immobilization Plant (WTP) Uniform feed to the WTP is a requirement of 24590-WTP-ICD-MG-01-019, ICD-19 - Interface Control Document for Waste Feed, although the exact definition of uniform is evolving in this context. Computational Fluid Dynamics (CFD) modeling has been used to assist in evaluating scaleup issues, study operational parameters, and predict mixing performance at full-scale.
Anglesio, P.; Negreanu, G.P.
1998-07-01T23:59:59.000Z
The purpose of this paper is to investigate by the means of numerical simulation the performance of the MSW incinerator with of Vercelli (Italy). FLUENT, a finite-volumes commercial code for Fluid Dynamics has been used to predict the 3-D reacting flows (gaseous phase) within the incinerator geometry, in order to estimate if the three conditions settled by the Italian law (P.D. 915 / 82) are respected: (a) Flue gas temperature at the input of the secondary combustion chamber must exceed 950 C. (b) Oxygen concentration in the same section must exceed 6 %. (c) Residence time for the flue gas in the secondary combustion chamber must exceed 2 seconds. The model of the incinerator has been created using the software pre-processing facilities (wall, input, outlet and live cells), together with the set-up of boundary conditions. There are also imposed the combustion constants (stoichiometry, heat of combustion, air excess). The solving procedure transforms at the level of each live cell the partial derivative equations in algebraic equations, computing the velocities field, the temperatures, gases concentration, etc. These predicted values were compared with the design properties, and the conclusion was that the conditions (a), (b), (c), are respected in normal operation. The powerful graphic interface helps the user to visualize the magnitude of the computed parameters. These results may be successfully used for the design and operation improvements for MSW incinerators. This fact will substantially increase the efficiency, reduce pollutant emissions and optimize the plant overall performance.
TILLMPAD NUMERISK STRMNINGSMEKANIK MVK150 Applied Computational Fluid Mechanics (CFD), basic course
TILLÃ?MPAD NUMERISK STRÃ?MNINGSMEKANIK MVK150 Applied Computational Fluid Mechanics (CFD), basic.D.; Computational Fluid Dynamics, The basics with applications, McGraw-Hill, 1995. #12;
Zevenhoven, Ron
Introduction to Computational Fluid Dynamics 424512 E #1 - rz Introduction to Computational Fluid Dynamics (iCFD) 424512.0 E, 5 sp / 3 sw 1. Introduction; Fluid dynamics (lecture 1 of 5) Ron Zevenhoven Ã?bo to Computational Fluid Dynamics 424512 E #1 - rz april 2013 Ã?bo Akademi Univ - Thermal and Flow Engineering
Three-Dimensional Computational Fluid Dynamics
Haworth, D.C.; O'Rourke, P.J.; Ranganathan, R.
1998-09-01T23:59:59.000Z
Computational fluid dynamics (CFD) is one discipline falling under the broad heading of computer-aided engineering (CAE). CAE, together with computer-aided design (CAD) and computer-aided manufacturing (CAM), comprise a mathematical-based approach to engineering product and process design, analysis and fabrication. In this overview of CFD for the design engineer, our purposes are three-fold: (1) to define the scope of CFD and motivate its utility for engineering, (2) to provide a basic technical foundation for CFD, and (3) to convey how CFD is incorporated into engineering product and process design.
Computational fluid dynamic applications
Chang, S.-L.; Lottes, S. A.; Zhou, C. Q.
2000-04-03T23:59:59.000Z
The rapid advancement of computational capability including speed and memory size has prompted the wide use of computational fluid dynamics (CFD) codes to simulate complex flow systems. CFD simulations are used to study the operating problems encountered in system, to evaluate the impacts of operation/design parameters on the performance of a system, and to investigate novel design concepts. CFD codes are generally developed based on the conservation laws of mass, momentum, and energy that govern the characteristics of a flow. The governing equations are simplified and discretized for a selected computational grid system. Numerical methods are selected to simplify and calculate approximate flow properties. For turbulent, reacting, and multiphase flow systems the complex processes relating to these aspects of the flow, i.e., turbulent diffusion, combustion kinetics, interfacial drag and heat and mass transfer, etc., are described in mathematical models, based on a combination of fundamental physics and empirical data, that are incorporated into the code. CFD simulation has been applied to a large variety of practical and industrial scale flow systems.
6. Fluid mechanics: fluid statics; fluid dynamics
Zevenhoven, Ron
1/96 6. Fluid mechanics: fluid statics; fluid dynamics (internal flows, external flows) Ron and Flow Engineering | 20500 Turku | Finland 2/96 6.1 Fluid statics Ã?bo Akademi University | Thermal and Flow Engineering | 20500 Turku | Finland #12;3/96 Fluid statics, static pressure /1 Two types
D'Sousa, Cedric Benedict
1997-01-01T23:59:59.000Z
realized information on the hood entry losses and other design parameters that are of interest to the users, designers and owners of fume hoods. After the specification of the problem and generation of the mesh, the modeled hood was simulated using CFD...
TILLMPAD NUMERISK STRMNINGSMEKANIK MVK 150 Applied Computational Fluid Mechanics (CFD), basic course
TILLÃ?MPAD NUMERISK STRÃ?MNINGSMEKANIK MVK 150 Applied Computational Fluid Mechanics (CFD), basic vanligaste lÃ¶sningsfÃ¶rfarandena presenteras och jÃ¤mfÃ¶rs. Litteratur Andersson, J.D.; Computational Fluid
Application of computational fluid dynamics to aerosol sampling and concentration
Hu, Shishan
2009-05-15T23:59:59.000Z
An understanding of gas-liquid two-phase interactions, aerosol particle deposition, and heat transfer is needed. Computational Fluid Dynamics (CFD) is becoming a powerful tool to predict aerosol behavior for related design work. In this study...
Computational Fluid Dynamics Study of Aerosol Transport and Deposition Mechanisms
Tang, Yingjie
2012-07-16T23:59:59.000Z
In this work, various aerosol particle transport and deposition mechanisms were studied through the computational fluid dynamics (CFD) modeling, including inertial impaction, gravitational effect, lift force, interception, and turbophoresis, within...
Seventh International Conference on Computational Fluid Dynamics (ICCFD7),
Boyer, Edmond
industrial purpose CFD codes, such as TONUS [7], to investigate turbulent combustion flows. The main drawback-diffusive scheme, upwind downwind-controlled splitting 1 Introduction The use of Computational Fluids Dynamics (CFD: the reaction zone in a laminar deflagration at atmospheric condition can vary from about 1 mm to 10 mm
Practical issues on CFD use and some industry aspects on research with CFD
Zevenhoven, Ron
Tampere #12;Our core areas of engineering are: Computational Fluid Dynamics (CFD) Structural Analysis (FEMPractical issues on CFD use and some industry aspects on research with CFD Sture BostrÃ¶m, 24.3.2011 Process Flow Ltd Oy www.processflow.fi #12;Outline Process Flow Ltd Oy Industrial example: CFD analysis
Computational fluid dynamics for the CFBR : challenges that lie ahead /
Kashiwa, B. A.; Yang, Wen-ching,
2001-01-01T23:59:59.000Z
The potential of Computational Fluid Dynamics as a tool for design and analysis of the Circulating Fluidized Bed Reactor is considered. The ruminations are largely philosophical in nature, and are based mainly on experience. An assessment of where CFD may, or may not, be a helpful tool for developing the needed understanding, is furnished. To motivate this assessment, a clarification of what composes a CFD analysis is provided. Status of CFD usage in CFBR problems is summarized briefly. Some successes and failures of CFD in CFBR analysis are also discussed; this suggests a practical way to proceed toward the goal of adding CFD as a useful tool, to be used in combination with well-defined experiments, for CFBR needs. The conclusion is that there remains substantial hope that CFD could be very useful in this application. In order to make the hope a reality, nontrivial, and achievable, advances in multiphase flow theory must be made.
Fluid dynamics of dilatant fluid
Hiizu Nakanishi; Shin-ichiro Nagahiro; Namiko Mitarai
2011-12-20T23:59:59.000Z
Dense mixture of granules and liquid often shows a sever shear thickening and is called a dilatant fluid. We construct a fluid dynamics model for the dilatant fluid by introducing a phenomenological state variable for a local state of dispersed particles. With simple assumptions for an equation of the state variable, we demonstrate that the model can describe basic features of the dilatant fluid such as the stress-shear rate curve that represents discontinuous severe shear thickening, hysteresis upon changing shear rate, instantaneous hardening upon external impact. Analysis of the model reveals that the shear thickening fluid shows an instability in a shear flow for some regime and exhibits {\\it the shear thickening oscillation}, i.e. the oscillatory shear flow alternating between the thickened and the relaxed states. Results of numerical simulations are presented for one and two-dimensional systems.
National Ignition Facility computational fluid dynamics modeling and light fixture case studies
Martin, R.; Bernardin, J.; Parietti, L.; Dennison, B.
1998-02-01T23:59:59.000Z
This report serves as a guide to the use of computational fluid dynamics (CFD) as a design tool for the National Ignition Facility (NIF) program Title I and Title II design phases at Lawrence Livermore National Laboratory. In particular, this report provides general guidelines on the technical approach to performing and interpreting any and all CFD calculations. In addition, a complete CFD analysis is presented to illustrate these guidelines on a NIF-related thermal problem.
Using the FLUENT computational fluid dynamics code to model the NACOK corrosion test
Parks, Benjamin T
2004-01-01T23:59:59.000Z
As a part of advancing nuclear technology, computational fluid dynamics (CFD) analysis offers safer and lower-cost results relative to experimental work. Its use as a safety analysis tool is gaining much broader acceptance ...
Zhai, Zhiqiang, 1971-
2003-01-01T23:59:59.000Z
Building energy simulation (ES) and computational fluid dynamics (CFD) can play important roles in building design by providing essential information to help design energy-efficient, thermally comfortable and healthy ...
Gao, Yang, 1974-
2002-01-01T23:59:59.000Z
Current design of building indoor environment comprises macroscopIC approaches, such as CONT AM multizone airflow analysis tool, and microscopic approaches that apply Computational Fluid Dynamics (CFD). Each has certain ...
Barran, Brian Arthur
2006-08-16T23:59:59.000Z
VIEW DEPENDENT FLUID DYNAMICS A Thesis by BRIAN ARTHUR BARRAN Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE May 2006 Major Subject: Visualization... Sciences VIEW DEPENDENT FLUID DYNAMICS A Thesis by BRIAN ARTHUR BARRAN Submitted to the Office of Graduate Studies of Texas A&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE Approved by: Chair of Committee, Donald...
Computational fluid dynamics modeling of coal gasification in a pressurized spout-fluid bed
Zhongyi Deng; Rui Xiao; Baosheng Jin; He Huang; Laihong Shen; Qilei Song; Qianjun Li [Southeast University, Nanjing (China). Key Laboratory of Clean Coal Power Generation and Combustion Technology of Ministry of Education
2008-05-15T23:59:59.000Z
Computational fluid dynamics (CFD) modeling, which has recently proven to be an effective means of analysis and optimization of energy-conversion processes, has been extended to coal gasification in this paper. A 3D mathematical model has been developed to simulate the coal gasification process in a pressurized spout-fluid bed. This CFD model is composed of gas-solid hydrodynamics, coal pyrolysis, char gasification, and gas phase reaction submodels. The rates of heterogeneous reactions are determined by combining Arrhenius rate and diffusion rate. The homogeneous reactions of gas phase can be treated as secondary reactions. A comparison of the calculated and experimental data shows that most gasification performance parameters can be predicted accurately. This good agreement indicates that CFD modeling can be used for complex fluidized beds coal gasification processes. 37 refs., 7 figs., 5 tabs.
Methodology for computational fluid dynamics code verification/validation
Oberkampf, W.L.; Blottner, F.G.; Aeschliman, D.P.
1995-07-01T23:59:59.000Z
The issues of verification, calibration, and validation of computational fluid dynamics (CFD) codes has been receiving increasing levels of attention in the research literature and in engineering technology. Both CFD researchers and users of CFD codes are asking more critical and detailed questions concerning the accuracy, range of applicability, reliability and robustness of CFD codes and their predictions. This is a welcomed trend because it demonstrates that CFD is maturing from a research tool to the world of impacting engineering hardware and system design. In this environment, the broad issue of code quality assurance becomes paramount. However, the philosophy and methodology of building confidence in CFD code predictions has proven to be more difficult than many expected. A wide variety of physical modeling errors and discretization errors are discussed. Here, discretization errors refer to all errors caused by conversion of the original partial differential equations to algebraic equations, and their solution. Boundary conditions for both the partial differential equations and the discretized equations will be discussed. Contrasts are drawn between the assumptions and actual use of numerical method consistency and stability. Comments are also made concerning the existence and uniqueness of solutions for both the partial differential equations and the discrete equations. Various techniques are suggested for the detection and estimation of errors caused by physical modeling and discretization of the partial differential equations.
Issues in computational fluid dynamics code verification and validation
Oberkampf, W.L.; Blottner, F.G.
1997-09-01T23:59:59.000Z
A broad range of mathematical modeling errors of fluid flow physics and numerical approximation errors are addressed in computational fluid dynamics (CFD). It is strongly believed that if CFD is to have a major impact on the design of engineering hardware and flight systems, the level of confidence in complex simulations must substantially improve. To better understand the present limitations of CFD simulations, a wide variety of physical modeling, discretization, and solution errors are identified and discussed. Here, discretization and solution errors refer to all errors caused by conversion of the original partial differential, or integral, conservation equations representing the physical process, to algebraic equations and their solution on a computer. The impact of boundary conditions on the solution of the partial differential equations and their discrete representation will also be discussed. Throughout the article, clear distinctions are made between the analytical mathematical models of fluid dynamics and the numerical models. Lax`s Equivalence Theorem and its frailties in practical CFD solutions are pointed out. Distinctions are also made between the existence and uniqueness of solutions to the partial differential equations as opposed to the discrete equations. Two techniques are briefly discussed for the detection and quantification of certain types of discretization and grid resolution errors.
Ship hull resistance calculations using CFD methods
Voxakis, Petros
2012-01-01T23:59:59.000Z
In past years, the computational power and run-time required by Computational Fluid Dynamics (CFD) codes restricted their use in ship design space exploration. Increases in computational power available to designers, in ...
MR-driven Computational Fluid Dynamics J-F. Nielsen1
Southern California, University of
MR-driven Computational Fluid Dynamics J-F. Nielsen1 , and K. S. Nayak2 1 Biomedical Engineering-encoding gradient pulse (VENC=1.6 m/s) was placed on the x, y, or z-gradient axis, or was turned off. MR-driven CFD component (vertical in Fig. 1) was incorporated into the MR-driven CFD solver. Hence, vx and vy were
Computational Fluid Dynamics of rising droplets
Wagner, Matthew [Lake Superior State University; Francois, Marianne M. [Los Alamos National Laboratory
2012-09-05T23:59:59.000Z
The main goal of this study is to perform simulations of droplet dynamics using Truchas, a LANL-developed computational fluid dynamics (CFD) software, and compare them to a computational study of Hysing et al.[IJNMF, 2009, 60:1259]. Understanding droplet dynamics is of fundamental importance in liquid-liquid extraction, a process used in the nuclear fuel cycle to separate various components. Simulations of a single droplet rising by buoyancy are conducted in two-dimensions. Multiple parametric studies are carried out to ensure the problem set-up is optimized. An Interface Smoothing Length (ISL) study and mesh resolution study are performed to verify convergence of the calculations. ISL is a parameter for the interface curvature calculation. Further, wall effects are investigated and checked against existing correlations. The ISL study found that the optimal ISL value is 2.5{Delta}x, with {Delta}x being the mesh cell spacing. The mesh resolution study found that the optimal mesh resolution is d/h=40, for d=drop diameter and h={Delta}x. In order for wall effects on terminal velocity to be insignificant, a conservative wall width of 9d or a nonconservative wall width of 7d can be used. The percentage difference between Hysing et al.[IJNMF, 2009, 60:1259] and Truchas for the velocity profiles vary from 7.9% to 9.9%. The computed droplet velocity and interface profiles are found in agreement with the study. The CFD calculations are performed on multiple cores, using LANL's Institutional High Performance Computing.
A. K. Chaudhuri
2007-03-12T23:59:59.000Z
We briefly discuss the phenomenological theory of dissipative fluid. We also present some numerical results for hydrodynamic evolution of QGP fluid with dissipation due to shear viscosity only. Its effect on particle production is also studied.
CFD Simulation of Dynamic Thrust and Radial Forces on a Vertical Axis Wind Turbine Blade
Tullis, Stephen
CFD Simulation of Dynamic Thrust and Radial Forces on a Vertical Axis Wind Turbine Blade K. Mc vibration source of a small scale vertical axis wind turbine. The dynamic loading on the blades of the turbine, as they rotate about the central shaft and travel through a range of relative angles of attack
Computational fluid dynamic modeling of fluidized-bed polymerization reactors
Rokkam, Ram [Ames Laboratory
2012-11-02T23:59:59.000Z
Polyethylene is one of the most widely used plastics, and over 60 million tons are produced worldwide every year. Polyethylene is obtained by the catalytic polymerization of ethylene in gas and liquid phase reactors. The gas phase processes are more advantageous, and use fluidized-bed reactors for production of polyethylene. Since they operate so close to the melting point of the polymer, agglomeration is an operational concern in all slurry and gas polymerization processes. Electrostatics and hot spot formation are the main factors that contribute to agglomeration in gas-phase processes. Electrostatic charges in gas phase polymerization fluidized bed reactors are known to influence the bed hydrodynamics, particle elutriation, bubble size, bubble shape etc. Accumulation of electrostatic charges in the fluidized-bed can lead to operational issues. In this work a first-principles electrostatic model is developed and coupled with a multi-fluid computational fluid dynamic (CFD) model to understand the effect of electrostatics on the dynamics of a fluidized-bed. The multi-fluid CFD model for gas-particle flow is based on the kinetic theory of granular flows closures. The electrostatic model is developed based on a fixed, size-dependent charge for each type of particle (catalyst, polymer, polymer fines) phase. The combined CFD model is first verified using simple test cases, validated with experiments and applied to a pilot-scale polymerization fluidized-bed reactor. The CFD model reproduced qualitative trends in particle segregation and entrainment due to electrostatic charges observed in experiments. For the scale up of fluidized bed reactor, filtered models are developed and implemented on pilot scale reactor.
Experimental methodology for computational fluid dynamics code validation
Aeschliman, D.P.; Oberkampf, W.L.
1997-09-01T23:59:59.000Z
Validation of Computational Fluid Dynamics (CFD) codes is an essential element of the code development process. Typically, CFD code validation is accomplished through comparison of computed results to previously published experimental data that were obtained for some other purpose, unrelated to code validation. As a result, it is a near certainty that not all of the information required by the code, particularly the boundary conditions, will be available. The common approach is therefore unsatisfactory, and a different method is required. This paper describes a methodology developed specifically for experimental validation of CFD codes. The methodology requires teamwork and cooperation between code developers and experimentalists throughout the validation process, and takes advantage of certain synergisms between CFD and experiment. The methodology employs a novel uncertainty analysis technique which helps to define the experimental plan for code validation wind tunnel experiments, and to distinguish between and quantify various types of experimental error. The methodology is demonstrated with an example of surface pressure measurements over a model of varying geometrical complexity in laminar, hypersonic, near perfect gas, 3-dimensional flow.
LECTURES IN ELEMENTARY FLUID DYNAMICS
McDonough, James M.
LECTURES IN ELEMENTARY FLUID DYNAMICS: Physics, Mathematics and Applications J. M. McDonough Departments of Mechanical Engineering and Mathematics University of Kentucky, Lexington, KY 40506-0503 c 1987, 1990, 2002, 2004, 2009 #12;Contents 1 Introduction 1 1.1 Importance of Fluids
Uncovering MIT wind myths through micro-climatological CFD analysis
Kalmikov, Alexander
2013-01-01T23:59:59.000Z
Popular campus myths of unusually strong pedestrian level winds are investigated with a Computational Fluid Dynamics (CFD) approach. The numerical simulations confirm the existence of the reported phenomena and provide a qualitative explanation of their physical mechanisms.
Optimization of a high-efficiency jet ejector by computational fluid dynamic software
Watanawanavet, Somsak
2005-08-29T23:59:59.000Z
Computational Fluid Dynamics (CFD) software. A conventional finite-volume scheme was utilized to solve two-dimensional transport equations with the standard k-?? turbulence model (Kim et. al., 1999). In this study of a constant-area jet ejector, all parameters...
A Simple Interface to Computational Fluid Dynamics Programs for Building Environment Simulations
Chen, Qingyan "Yan"
. SCI can be easily integrated into new CFD programs. Introduction Advanced building design requests and pressure distributions that are crucial for thermal comfort and building structure designs. TraditionallyA Simple Interface to Computational Fluid Dynamics Programs for Building Environment Simulations
Nonlinear Fluid Dynamics from Gravity
Sayantani Bhattacharyya; Veronika E Hubeny; Shiraz Minwalla; Mukund Rangamani
2008-04-02T23:59:59.000Z
Black branes in AdS5 appear in a four parameter family labeled by their velocity and temperature. Promoting these parameters to Goldstone modes or collective coordinate fields -- arbitrary functions of the coordinates on the boundary of AdS5 -- we use Einstein's equations together with regularity requirements and boundary conditions to determine their dynamics. The resultant equations turn out to be those of boundary fluid dynamics, with specific values for fluid parameters. Our analysis is perturbative in the boundary derivative expansion but is valid for arbitrary amplitudes. Our work may be regarded as a derivation of the nonlinear equations of boundary fluid dynamics from gravity. As a concrete application we find an explicit expression for the expansion of this fluid stress tensor including terms up to second order in the derivative expansion.
Technical Review of the CENWP Computational Fluid Dynamics Model of the John Day Dam Forebay
Rakowski, Cynthia L.; Serkowski, John A.; Richmond, Marshall C.
2010-12-01T23:59:59.000Z
The US Army Corps of Engineers Portland District (CENWP) has developed a computational fluid dynamics (CFD) model of the John Day forebay on the Columbia River to aid in the development and design of alternatives to improve juvenile salmon passage at the John Day Project. At the request of CENWP, Pacific Northwest National Laboratory (PNNL) Hydrology Group has conducted a technical review of CENWP's CFD model run in CFD solver software, STAR-CD. PNNL has extensive experience developing and applying 3D CFD models run in STAR-CD for Columbia River hydroelectric projects. The John Day forebay model developed by CENWP is adequately configured and validated. The model is ready for use simulating forebay hydraulics for structural and operational alternatives. The approach and method are sound, however CENWP has identified some improvements that need to be made for future models and for modifications to this existing model.
Department of Mechanical Engineering Spring 2013 CFD Model of a Gypsum Mixer
Demirel, Melik C.
PENNSTATE Department of Mechanical Engineering Spring 2013 CFD Model of a Gypsum Mixer Overview This project, in continuation of last semester's team, intends to create a computational fluid dynamic (CFD) model of the fluid flow inside CertainTeed Gypsum's gypsum mixer. Currently, the mixer outputs locally
Stosic, Zoran V. [Framatome ANP GmbH, P.O. Box 3220, 91050 Erlangen (Germany); Stevanovic, Vladimir D. [University of Belgrade, Kraljice Marije 16, 11000 Belgrade, Serbia and Montenegro (Yugoslavia)
2002-07-01T23:59:59.000Z
Computational fluid dynamics for multiphase flows is an emerging field. Due to the complexity and divergence of multiphase thermal and hydraulic problems, further development of multiphase flow modelling, closure laws and numerical methods is needed in order to achieve the general purpose and optimised CFD (Computational Fluid Dynamics) methods, which will be applicable to the wide variety of multiphase flow problems. In the paper, an original approach to the various aspects of multiphase CFD modelling is presented. It is based on the multi-fluid modelling approach, development of necessary closure laws and derivation of appropriate numerical methods for efficient governing equations solution. Velocity and pressure fields are solved with the SIMPLE (Semi-Implicit Method for Pressure-Linked Equations) type pressure-corrector method developed for the multiphase flow conditions. For the solution of scalar parameters transport equations both implicit and explicit methods are presented. The implicit method is suitable for steady state, slow transients and problems without the sharp fronts propagation. Explicit method is developed in order to predict scalar parameters fronts propagation, as well as phase interface tracking problems. The challenge towards the multiphase flow solution on both the macro and micro level is presented in order to perform multiphase CFD simulations and analyses of multiphase flows in complex geometry of nuclear power plant components, such as nuclear fuel rod bundles thermal-hydraulics. Presented methodology and obtained CFD results comprise micro-scale phenomena of phases' separation, interface tracking, heated surfaces dry-out and critical heat flux occurrence, as well as macro-scale transport and distributions of phase volumes. (authors)
Computational Fluid Dynamics Simulation of Fluidized Bed Polymerization Reactors
Rong Fan
2006-08-09T23:59:59.000Z
Fluidized beds (FB) reactors are widely used in the polymerization industry due to their superior heat- and mass-transfer characteristics. Nevertheless, problems associated with local overheating of polymer particles and excessive agglomeration leading to FB reactors defluidization still persist and limit the range of operating temperatures that can be safely achieved in plant-scale reactors. Many people have been worked on the modeling of FB polymerization reactors, and quite a few models are available in the open literature, such as the well-mixed model developed by McAuley, Talbot, and Harris (1994), the constant bubble size model (Choi and Ray, 1985) and the heterogeneous three phase model (Fernandes and Lona, 2002). Most these research works focus on the kinetic aspects, but from industrial viewpoint, the behavior of FB reactors should be modeled by considering the particle and fluid dynamics in the reactor. Computational fluid dynamics (CFD) is a powerful tool for understanding the effect of fluid dynamics on chemical reactor performance. For single-phase flows, CFD models for turbulent reacting flows are now well understood and routinely applied to investigate complex flows with detailed chemistry. For multiphase flows, the state-of-the-art in CFD models is changing rapidly and it is now possible to predict reasonably well the flow characteristics of gas-solid FB reactors with mono-dispersed, non-cohesive solids. This thesis is organized into seven chapters. In Chapter 2, an overview of fluidized bed polymerization reactors is given, and a simplified two-site kinetic mechanism are discussed. Some basic theories used in our work are given in detail in Chapter 3. First, the governing equations and other constitutive equations for the multi-fluid model are summarized, and the kinetic theory for describing the solid stress tensor is discussed. The detailed derivation of DQMOM for the population balance equation is given as the second section. In this section, monovariate population balance, bivariate population balance, aggregation and breakage equation and DQMOM-Multi-Fluid model are described. In the last section of Chapter 3, numerical methods involved in the multi-fluid model and time-splitting method are presented. Chapter 4 is based on a paper about application of DQMOM to polydisperse gas-solid fluidized beds. Results for a constant aggregation and breakage kernel and a kernel developed from kinetic theory are shown. The effect of the aggregation success factor and the fragment distribution function are investigated. Chapter 5 shows the work on validation of mixing and segregation phenomena in gas-solid fluidized beds with a binary mixture or a continuous size distribution. The simulation results are compared with available experiment data and discrete-particle simulation. Chapter 6 presents the project with Univation Technologies on CFD simulation of a Polyethylene pilot-scale FB reactor, The fluid dynamics, mass/heat transfer and particle size distribution are investigated through CFD simulation and validated with available experimental data. The conclusions of this study and future work are discussed in Chapter 7.
European Conference on Computational Fluid Dynamics ECCOMAS CFD 2006
Frangi, Alejandro
in industrialized countries. The major CVD include coronary (or ischaemic) heart disease (heart attack), cerebrovascular disease (stroke), hypertension (high blood pressure), rheumatic heart disease and heart failure. Damage to the heart tissues from CVD or from heart surgery can disrupt the natural electrical impulses
Modeling an EDC Cracker using Computational Fluid Dynamics (CFD).
Kaggerud, Torbjørn Herder
2007-01-01T23:59:59.000Z
?? The process used by the Norwegian company Hydro for making Vinyl Chloride Monomer (VCM) from natural gas and sodium chloride has been studied. A… (more)
V European Conference on Computational Fluid Dynamics ECCOMAS CFD 2010
MÃ¼ller,Bernhard
an important role include ink-jet printing, spray cooling, pesticide spraying, erosion processes due to rain and ther- mal spray coating. Drop impacts also play an important role in gas-liquid separation.g. density and viscosity are smeared out over several grid points. The result of those diffuse interface
European Conference on Computational Fluid Dynamics ECCOMAS CFD 2006
Al Hanbali, Ahmad
217, 7500 AE Enschede, The Netherlands e-mail: {L.Pesch, J.J.W.vanderVegt}@math.utwente.nl web page. PÂ´eriaux (Eds) c TU Delft, The Netherlands, 2006 A SPACE-TIME DISCONTINUOUS GALERKIN FINITE
European Conference on Computational Fluid Dynamics ECCOMAS CFD 2006
Al Hanbali, Ahmad
of Twente P.O. Box 217, Enschede, The Netherlands e-mail: o.bokhove@math.utwente.nl web page: google "Onno. PÂ´eriaux (Eds) c TU Delft, The Netherlands, 2006 A (DIS)CONTINUOUS FINITE ELEMENT MODEL of Physics, University of Utrecht, Utrecht, The Netherlands Department of Applied Mathematics, University
Lawson, M. J.; Li, Y.; Sale, D. C.
2011-10-01T23:59:59.000Z
This paper describes the development of a computational fluid dynamics (CFD) methodology to simulate the hydrodynamics of horizontal-axis tidal current turbines. Qualitative measures of the CFD solutions were independent of the grid resolution. Conversely, quantitative comparisons of the results indicated that the use of coarse computational grids results in an under prediction of the hydrodynamic forces on the turbine blade in comparison to the forces predicted using more resolved grids. For the turbine operating conditions considered in this study, the effect of the computational timestep on the CFD solution was found to be minimal, and the results from steady and transient simulations were in good agreement. Additionally, the CFD results were compared to corresponding blade element momentum method calculations and reasonable agreement was shown. Nevertheless, we expect that for other turbine operating conditions, where the flow over the blade is separated, transient simulations will be required.
Complete CFD analysis of a Velocity XL-5 RG with flight-test verification
Schouten, Shane Michael
2008-10-10T23:59:59.000Z
of the canard wake and Computational Fluid Dynamics (CFD) were used to provide a clear picture of the flowfield around the aircraft. The first step of the project consisted of making a 3-D CAD model of the aircraft. This model was then used for the CFD...
Computational Fluid Dynamics Framework for Turbine Biological Performance Assessment
Richmond, Marshall C.; Serkowski, John A.; Carlson, Thomas J.; Ebner, Laurie L.; Sick, Mirjam; Cada, G. F.
2011-05-04T23:59:59.000Z
In this paper, a method for turbine biological performance assessment is introduced to bridge the gap between field and laboratory studies on fish injury and turbine design. Using this method, a suite of biological performance indicators is computed based on simulated data from a computational fluid dynamics (CFD) model of a proposed turbine design. Each performance indicator is a measure of the probability of exposure to a certain dose of an injury mechanism. If the relationship between the dose of an injury mechanism and frequency of injury (dose-response) is known from laboratory or field studies, the likelihood of fish injury for a turbine design can be computed from the performance indicator. By comparing the values of the indicators from various turbine designs, the engineer can identify the more-promising designs. Discussion here is focused on Kaplan-type turbines, although the method could be extended to other designs. Following the description of the general methodology, we will present sample risk assessment calculations based on CFD data from a model of the John Day Dam on the Columbia River in the USA.
CFD evaluation of pipeline gas stratification at low fluid flow due to temperature effects
Brar, Pardeep Singh
2005-02-17T23:59:59.000Z
variance in chord averaged velocities is apparent at these conditions. CFD analysis was performed. Low flow velocities of 0.1524 m/sec, 0.3048 m/sec and 0.6096 m/sec and temperature differences of 5.5 o K, 13.8 o K and 27.7 o K were considered. When... with gas velocity below 0.6096 m/sec. v DEDICATION To my family for their love and support. vi ACKNOWLEDGMENTS I would like to express my gratitude to Dr. Gerald Morrison for his valuable guidance and support. I...
Computational Fluid Dynamic Analysis of the VHTR Lower Plenum Standard Problem
Richard W. Johnson; Richard R. Schultz
2009-07-01T23:59:59.000Z
The United States Department of Energy is promoting the resurgence of nuclear power in the U. S. for both electrical power generation and production of process heat required for industrial processes such as the manufacture of hydrogen for use as a fuel in automobiles. The DOE project is called the next generation nuclear plant (NGNP) and is based on a Generation IV reactor concept called the very high temperature reactor (VHTR), which will use helium as the coolant at temperatures ranging from 450 ºC to perhaps 1000 ºC. While computational fluid dynamics (CFD) has not been used for past safety analysis for nuclear reactors in the U. S., it is being considered for safety analysis for existing and future reactors. It is fully recognized that CFD simulation codes will have to be validated for flow physics reasonably close to actual fluid dynamic conditions expected in normal and accident operational situations. To this end, experimental data have been obtained in a scaled model of a narrow slice of the lower plenum of a prismatic VHTR. The present report presents results of CFD examinations of these data to explore potential issues with the geometry, the initial conditions, the flow dynamics and the data needed to fully specify the inlet and boundary conditions; results for several turbulence models are examined. Issues are addressed and recommendations about the data are made.
A proposed framework for computational fluid dynamics code calibration/validation
Oberkampf, W.L.
1993-12-31T23:59:59.000Z
The paper reviews the terminology and methodology that have been introduced during the last several years for building confidence n the predictions from Computational Fluid Dynamics (CID) codes. Code validation terminology developed for nuclear reactor analyses and aerospace applications is reviewed and evaluated. Currently used terminology such as ``calibrated code,`` ``validated code,`` and a ``validation experiment`` is discussed along with the shortcomings and criticisms of these terms. A new framework is proposed for building confidence in CFD code predictions that overcomes some of the difficulties of past procedures and delineates the causes of uncertainty in CFD predictions. Building on previous work, new definitions of code verification and calibration are proposed. These definitions provide more specific requirements for the knowledge level of the flow physics involved and the solution accuracy of the given partial differential equations. As part of the proposed framework, categories are also proposed for flow physics research, flow modeling research, and the application of numerical predictions. The contributions of physical experiments, analytical solutions, and other numerical solutions are discussed, showing that each should be designed to achieve a distinctively separate purpose in building confidence in accuracy of CFD predictions. A number of examples are given for each approach to suggest methods for obtaining the highest value for CFD code quality assurance.
Computational Fluid Dynamics in Support of the SNS Liquid Mercury Thermal-Hydraulic Analysis
Siman-Tov, M.; Wendel, M.W.; Yoder, G.L.
1999-11-14T23:59:59.000Z
Experimental and computational thermal-hydraulic research is underway to support the liquid mercury target design for the Spallation Neutron Source (SNS) facility. The SNS target will be subjected to internal nuclear heat generation that results from pulsed proton beam collisions with the mercury nuclei. Recirculation and stagnation zones within the target are of particular concern because of the likelihood that they will result in local hot spots and diminished heat removal from the target structure. Computational fluid dynamics (CFD) models are being used as a part of this research. Recent improvements to the 3D target model include the addition of the flow adapter which joins the inlet/outlet coolant pipes to the target body and an updated heat load distribution at the new baseline proton beam power level of 2 MW. Two thermal-hydraulic experiments are planned to validate the CFD model.
Investigation of Swirling Flow in Rod Bundle Subchannels Using Computational Fluid Dynamics
Holloway, Mary V. [United States Naval Academy, 117 Decatur Road, Annapolis, MD 21402-5018 (United States); Beasley, Donald E. [Clemson University, Clemson, S.C. 29634 (United States); Conner, Michael E. [Westinghouse Nuclear Fuel (United States)
2006-07-01T23:59:59.000Z
The fluid dynamics for turbulent flow through rod bundles representative of those used in pressurized water reactors is examined using computational fluid dynamics (CFD). The rod bundles of the pressurized water reactor examined in this study consist of a square array of parallel rods that are held on a constant pitch by support grids spaced axially along the rod bundle. Split-vane pair support grids are often used to create swirling flow in the rod bundle in an effort to improve the heat transfer characteristics for the rod bundle during both normal operating conditions and in accident condition scenarios. Computational fluid dynamics simulations for a two subchannel portion of the rod bundle were used to model the flow downstream of a split-vane pair support grid. A high quality computational mesh was used to investigate the choice of turbulence model appropriate for the complex swirling flow in the rod bundle subchannels. Results document a central swirling flow structure in each of the subchannels downstream of the split-vane pairs. Strong lateral flows along the surface of the rods, as well as impingement regions of lateral flow on the rods are documented. In addition, regions of lateral flow separation and low axial velocity are documented next to the rods. Results of the CFD are compared to experimental particle image velocimetry (PIV) measurements documenting the lateral flow structures downstream of the split-vane pairs. Good agreement is found between the computational simulation and experimental measurements for locations close to the support grid. (authors)
CFD analysis uncovers ways to lower condenser pressure drop
Rhodes, N.; Bell, R.J.
1994-05-01T23:59:59.000Z
This article describes the use of computer simulation to evaluate condenser performance and evaluate proposed modifications to the condenser. The topics of the article include the basic principles of computational fluid dynamics (CFD), surface condenser design, performance evaluation, pressure drop reduction, application to a United Kingdom utility.
Fluid Dynamics in Sucker Rod Pumps
Cutler, R.P.; Mansure, A.J.
1999-01-14T23:59:59.000Z
Sucker rod pumps are installed in approximately 90% of all oil wells in the U.S. Although they have been widely used for decades, there are many issues regarding the fluid dynamics of the pump that have not been fully investigated. A project was conducted at Sandia National Laboratories to develop unimproved understanding of the fluid dynamics inside a sucker rod pump. A mathematical flow model was developed to predict pressures in any pump component or an entire pump under single-phase fluid and pumping conditions. Laboratory flow tests were conducted on instrumented individual pump components and on a complete pump to verify and refine the model. The mathematical model was then converted to a Visual Basic program to allow easy input of fluid, geometry and pump parameters and to generate output plots. Examples of issues affecting pump performance investigated with the model include the effects of viscosity, surface roughness, valve design details, plunger and valve pressure differentials, and pumping rate.
Hag, M.A.
1982-08-01T23:59:59.000Z
A study was conducted to investigate the effects of fluid properties on the hydrodynamics of sieve tray columns. The study showed that changes in liquid viscosity influenced froth height, while changes in liquid surface tension and density influenced total pressure drop across the trays. Liquid holdup was independent of these solution properties. The liquid systems used for the study were: water/glycerol for viscosity, water/ethanol for surface tension and methanol/chloroform for density.
Fluid dynamics kill Wyoming icicle
Grace, R.D.
1987-04-01T23:59:59.000Z
Control of a blowout in which a portion of the drill collar string was extending through the rotary table and into the derrick was compounded by ice building up on the derrick and substructure. However, the momentum kill procedure proved successful. Topics considered in this paper include oil wells, natural gas wells, sleeves, rotary drills, drilling rigs, fluid mechanics, occupational safety, blowouts, drill pipes, rotary drilling, ice removal, and freezing.
Robust processing of optical flow of fluids Ashish Doshi and Adrian G. Bors, Senior Member, IEEE
Bors, Adrian
the computational fluid dynamics (CFD). Navier-Stokes equations have been extensively studied in fluid mechanics Terms--Optical flow of fluids, computational fluid dy- namics, diffusion, vortex detection I displaying fluid movement. Velocity fields, characterizing the motion of fluids can be modelled using
Formulation, Implementation and Validation of a Two-Fluid model in a Fuel Cell CFD Code
Kunal Jain, Vernon Cole, Sanjiv Kumar and N. Vaidya
2008-11-01T23:59:59.000Z
Water management is one of the main challenges in PEM Fuel Cells. While water is essential for membrane electrical conductivity, excess liquid water leads to ooding of catalyst layers. Despite the fact that accurate prediction of two-phase transport is key for optimal water management, understanding of the two-phase transport in fuel cells is relatively poor. Wang et. al. [1], [2] have studied the two-phase transport in the channel and diffusion layer separately using a multiphase mixture model. The model fails to accurately predict saturation values for high humidity inlet streams. Nguyen et. al. [3] developed a two-dimensional, two-phase, isothermal, isobaric, steady state model of the catalyst and gas diffusion layers. The model neglects any liquid in the channel. Djilali et. al. [4] developed a three-dimensional two-phase multicomponent model. The model is an improvement over previous models, but neglects drag between the liquid and the gas phases in the channel. In this work, we present a comprehensive two- fluid model relevant to fuel cells. Models for two-phase transport through Channel, Gas Diffusion Layer (GDL) and Channel-GDL interface, are discussed. In the channel, the gas and liquid pressures are assumed to be same. The surface tension effects in the channel are incorporated using the continuum surface force (CSF) model. The force at the surface is expressed as a volumetric body force and added as a source to the momentum equation. In the GDL, the gas and liquid are assumed to be at different pressures. The difference in the pressures (capillary pressure) is calculated using an empirical correlations. At the Channel-GDL interface, the wall adhesion affects need to be taken into account. SIMPLE-type methods recast the continuity equation into a pressure-correction equation, the solution of which then provides corrections for velocities and pressures. However, in the two-fluid model, the presence of two phasic continuity equations gives more freedom and more complications. A general approach would be to form a mixture continuity equation by linearly combining the phasic continuity equations using appropriate weighting factors. Analogous to mixture equation for pressure correction, a difference equation is used for the volume/phase fraction by taking the difference between the phasic continuity equations. The relative advantages of the above mentioned algorithmic variants for computing pressure correction and volume fractions are discussed and quantitatively assessed. Preliminary model validation is done for each component of the fuel cell. The two-phase transport in the channel is validated using empirical correlations. Transport in the GDL is validated against results obtained from LBM and VOF simulation techniques. The Channel-GDL interface transport will be validated against experiment and empirical correlation of droplet detachment at the interface. References [1] Y. Wang S. Basu and C.Y. Wang. Modeling two-phase flow in pem fuel cell channels. J. Power Sources, 179:603{617, 2008. [2] P. K. Sinha and C. Y. Wang. Liquid water transport in a mixed-wet gas diffusion layer of a polymer electrolyte fuel cell. Chem. Eng. Sci., 63:1081-1091, 2008. [3] Guangyu Lin and Trung Van Nguyen. A two-dimensional two-phase model of a pem fuel cell. J. Electrochem. Soc., 153(2):A372{A382, 2006. [4] T. Berning and N. Djilali. A 3d, multiphase, multicomponent model of the cathode and anode of a pem fuel cell. J. Electrochem. Soc., 150(12):A1589{A1598, 2003.
Computational Fluid Dynamics Analysis of Flexible Duct Junction Box Design
Beach, R.; Prahl, D.; Lange, R.
2013-12-01T23:59:59.000Z
IBACOS explored the relationships between pressure and physical configurations of flexible duct junction boxes by using computational fluid dynamics (CFD) simulations to predict individual box parameters and total system pressure, thereby ensuring improved HVAC performance. Current Air Conditioning Contractors of America (ACCA) guidance (Group 11, Appendix 3, ACCA Manual D, Rutkowski 2009) allows for unconstrained variation in the number of takeoffs, box sizes, and takeoff locations. The only variables currently used in selecting an equivalent length (EL) are velocity of air in the duct and friction rate, given the first takeoff is located at least twice its diameter away from the inlet. This condition does not account for other factors impacting pressure loss across these types of fittings. For each simulation, the IBACOS team converted pressure loss within a box to an EL to compare variation in ACCA Manual D guidance to the simulated variation. IBACOS chose cases to represent flows reasonably correlating to flows typically encountered in the field and analyzed differences in total pressure due to increases in number and location of takeoffs, box dimensions, and velocity of air, and whether an entrance fitting is included. The team also calculated additional balancing losses for all cases due to discrepancies between intended outlet flows and natural flow splits created by the fitting. In certain asymmetrical cases, the balancing losses were significantly higher than symmetrical cases where the natural splits were close to the targets. Thus, IBACOS has shown additional design constraints that can ensure better system performance.
Aeschliman, D.P.; Oberkampf, W.L.; Blottner, F.G.
1995-07-01T23:59:59.000Z
Verification, calibration, and validation (VCV) of Computational Fluid Dynamics (CFD) codes is an essential element of the code development process. The exact manner in which code VCV activities are planned and conducted, however, is critically important. It is suggested that the way in which code validation, in particular, is often conducted--by comparison to published experimental data obtained for other purposes--is in general difficult and unsatisfactory, and that a different approach is required. This paper describes a proposed methodology for CFD code VCV that meets the technical requirements and is philosophically consistent with code development needs. The proposed methodology stresses teamwork and cooperation between code developers and experimentalists throughout the VCV process, and takes advantage of certain synergisms between CFD and experiment. A novel approach to uncertainty analysis is described which can both distinguish between and quantify various types of experimental error, and whose attributes are used to help define an appropriate experimental design for code VCV experiments. The methodology is demonstrated with an example of laminar, hypersonic, near perfect gas, 3-dimensional flow over a sliced sphere/cone of varying geometrical complexity.
Computational Fluid Dynamics Analyses on Very High Temperature Reactor Air Ingress
Chang H Oh; Eung S. Kim; Richard Schultz; David Petti; Hyung S. Kang
2009-07-01T23:59:59.000Z
A preliminary computational fluid dynamics (CFD) analysis was performed to understand density-gradient-induced stratified flow in a Very High Temperature Reactor (VHTR) air-ingress accident. Various parameters were taken into consideration, including turbulence model, core temperature, initial air mole-fraction, and flow resistance in the core. The gas turbine modular helium reactor (GT-MHR) 600 MWt was selected as the reference reactor and it was simplified to be 2-D geometry in modeling. The core and the lower plenum were assumed to be porous bodies. Following the preliminary CFD results, the analysis of the air-ingress accident has been performed by two different codes: GAMMA code (system analysis code, Oh et al. 2006) and FLUENT CFD code (Fluent 2007). Eventually, the analysis results showed that the actual onset time of natural convection (~160 sec) would be significantly earlier than the previous predictions (~150 hours) calculated based on the molecular diffusion air-ingress mechanism. This leads to the conclusion that the consequences of this accident will be much more serious than previously expected.
Rakowski, Cynthia L.; Richmond, Marshall C.; Serkowski, John A.
2006-12-01T23:59:59.000Z
A computational fluid dynamics (CFD) model was used in an investigation into the suppression of a surface vortex that forms and the south-most spilling bay at The Dalles Project. The CFD work complemented work at the prototype and the reduced-scale physical models. The CFD model was based on a model developed for other work in the forebay but had additional resolution added near the spillway. Vortex suppression devices (VSDs) were to placed between pier noses and/or in the bulkhead slot of the spillway bays. The simulations in this study showed that placing VSD structures or a combination of structures to suppress the vortex would still result in near-surface flows to be entrained in a vortex near the downstream spillwall. These results were supported by physical model and prototype studies. However, there was a consensus of the fish biologists at the physical model that the fish would most likely move north and if the fish went under the VSD it would immediately exit the forebay through the tainter gate and not get trapped between VSDs or the VSDs and the tainter gate if the VSDs were deep enough.
Code Verification of the HIGRAD Computational Fluid Dynamics Solver
Van Buren, Kendra L. [Los Alamos National Laboratory; Canfield, Jesse M. [Los Alamos National Laboratory; Hemez, Francois M. [Los Alamos National Laboratory; Sauer, Jeremy A. [Los Alamos National Laboratory
2012-05-04T23:59:59.000Z
The purpose of this report is to outline code and solution verification activities applied to HIGRAD, a Computational Fluid Dynamics (CFD) solver of the compressible Navier-Stokes equations developed at the Los Alamos National Laboratory, and used to simulate various phenomena such as the propagation of wildfires and atmospheric hydrodynamics. Code verification efforts, as described in this report, are an important first step to establish the credibility of numerical simulations. They provide evidence that the mathematical formulation is properly implemented without significant mistakes that would adversely impact the application of interest. Highly accurate analytical solutions are derived for four code verification test problems that exercise different aspects of the code. These test problems are referred to as: (i) the quiet start, (ii) the passive advection, (iii) the passive diffusion, and (iv) the piston-like problem. These problems are simulated using HIGRAD with different levels of mesh discretization and the numerical solutions are compared to their analytical counterparts. In addition, the rates of convergence are estimated to verify the numerical performance of the solver. The first three test problems produce numerical approximations as expected. The fourth test problem (piston-like) indicates the extent to which the code is able to simulate a 'mild' discontinuity, which is a condition that would typically be better handled by a Lagrangian formulation. The current investigation concludes that the numerical implementation of the solver performs as expected. The quality of solutions is sufficient to provide credible simulations of fluid flows around wind turbines. The main caveat associated to these findings is the low coverage provided by these four problems, and somewhat limited verification activities. A more comprehensive evaluation of HIGRAD may be beneficial for future studies.
Development of a CFD Analysis Plan for the first VHTR Standard Problem
Richard W. Johnson
2008-09-01T23:59:59.000Z
Data from a scaled model of a portion of the lower plenum of the helium-cooled very high temperature reactor (VHTR) are under consideration for acceptance as a computational fluid dynamics (CFD) validation data set or standard problem. A CFD analysis will help determine if the scaled model is a suitable geometry for validation data. The present article describes the development of an analysis plan for the CFD model. The plan examines the boundary conditions that should be used, the extent of the computational domain that should be included and which turbulence models need not be examined against the data. Calculations are made for a closely related 2D geometry to address these issues. It was found that a CFD model that includes only the inside of the scaled model in its computational domain is adequate for CFD calculations. The realizable k~e model was found not to be suitable for this problem because it did not predict vortex-shedding.
Gustavsen, Arlid; Kohler, Christian; Dalehaug, Arvid; Arasteh, Dariush
2008-12-01T23:59:59.000Z
This paper assesses the accuracy of the simplified frame cavity conduction/convection and radiation models presented in ISO 15099 and used in software for rating and labeling window products. Temperatures and U-factors for typical horizontal window frames with internal cavities are compared; results from Computational Fluid Dynamics (CFD) simulations with detailed radiation modeling are used as a reference. Four different frames were studied. Two were made of polyvinyl chloride (PVC) and two of aluminum. For each frame, six different simulations were performed, two with a CFD code and four with a building-component thermal-simulation tool using the Finite Element Method (FEM). This FEM tool addresses convection using correlations from ISO 15099; it addressed radiation with either correlations from ISO 15099 or with a detailed, view-factor-based radiation model. Calculations were performed using the CFD code with and without fluid flow in the window frame cavities; the calculations without fluid flow were performed to verify that the CFD code and the building-component thermal-simulation tool produced consistent results. With the FEM-code, the practice of subdividing small frame cavities was examined, in some cases not subdividing, in some cases subdividing cavities with interconnections smaller than five millimeters (mm) (ISO 15099) and in some cases subdividing cavities with interconnections smaller than seven mm (a breakpoint that has been suggested in other studies). For the various frames, the calculated U-factors were found to be quite comparable (the maximum difference between the reference CFD simulation and the other simulations was found to be 13.2 percent). A maximum difference of 8.5 percent was found between the CFD simulation and the FEM simulation using ISO 15099 procedures. The ISO 15099 correlation works best for frames with high U-factors. For more efficient frames, the relative differences among various simulations are larger. Temperature was also compared, at selected locations on the frames. Small differences was found in the results from model to model. Finally, the effectiveness of the ISO cavity radiation algorithms was examined by comparing results from these algorithms to detailed radiation calculations (from both programs). Our results suggest that improvements in cavity heat transfer calculations can be obtained by using detailed radiation modeling (i.e. view-factor or ray-tracing models), and that incorporation of these strategies may be more important for improving the accuracy of results than the use of CFD modeling for horizontal cavities.
Rakowski, Cynthia L.; Richmond, Marshall C.; Serkowski, John A.; Johnson, Gary E.
2005-03-10T23:59:59.000Z
Computational fluid dynamics (CFD) models were developed to support the siting and design of a behavioral guidance system (BGS) structure in The Dalles Dam (TDA) forebay on the Columbia River. The work was conducted by Pacific Northwest National Laboratory for the U.S. Army Corps of Engineers, Portland District (CENWP). The CFD results were an invaluable tool for the analysis, both from a Regional and Agency perspective (for the fish passage evaluation) and a CENWP perspective (supporting the BGS design and location). The new CFD model (TDA forebay model) included the latest bathymetry (surveyed in 1999) and a detailed representation of the engineered structures (spillway, powerhouse main, fish, and service units). The TDA forebay model was designed and developed in a way that future studies could easily modify or, to a large extent, reuse large portions of the existing mesh. This study resulted in these key findings: (1) The TDA forebay model matched well with field-measured velocity data. (2) The TDA forebay model matched observations made at the 1:80 general physical model of the TDA forebay. (3) During the course of this study, the methodology typically used by CENWP to contour topographic data was shown to be inaccurate when applied to widely-spaced transect data. Contouring methodologies need to be revisited--especially before such things as modifying the bathymetry in the 1:80 general physical model are undertaken. Future alignments can be evaluated with the model staying largely intact. The next round of analysis will need to address fish passage demands and navigation concerns. CFD models can be used to identify the most promising locations and to provide quantified metrics for biological, hydraulic, and navigation criteria. The most promising locations should then be further evaluated in the 1:80 general physical model.
Computational Fluid Dynamics Best Practice Guidelines in the Analysis of Storage Dry Cask
Zigh, A.; Solis, J. [US Nuclear Regulatory Commission, Rockville, MD MS (United States)
2008-07-01T23:59:59.000Z
Computational fluid dynamics (CFD) methods are used to evaluate the thermal performance of a dry cask under long term storage conditions in accordance with NUREG-1536 [NUREG-1536, 1997]. A three-dimensional CFD model was developed and validated using data for a ventilated storage cask (VSC-17) collected by Idaho National Laboratory (INL). The developed Fluent CFD model was validated to minimize the modeling and application uncertainties. To address modeling uncertainties, the paper focused on turbulence modeling of buoyancy driven air flow. Similarly, in the application uncertainties, the pressure boundary conditions used to model the air inlet and outlet vents were investigated and validated. Different turbulence models were used to reduce the modeling uncertainty in the CFD simulation of the air flow through the annular gap between the overpack and the multi-assembly sealed basket (MSB). Among the chosen turbulence models, the validation showed that the low Reynolds k-{epsilon} and the transitional k-{omega} turbulence models predicted the measured temperatures closely. To assess the impact of pressure boundary conditions used at the air inlet and outlet channels on the application uncertainties, a sensitivity analysis of operating density was undertaken. For convergence purposes, all available commercial CFD codes include the operating density in the pressure gradient term of the momentum equation. The validation showed that the correct operating density corresponds to the density evaluated at the air inlet condition of pressure and temperature. Next, the validated CFD method was used to predict the thermal performance of an existing dry cask storage system. The evaluation uses two distinct models: a three-dimensional and an axisymmetrical representation of the cask. In the 3-D model, porous media was used to model only the volume occupied by the rodded region that is surrounded by the BWR channel box. In the axisymmetric model, porous media was used to model the entire region that encompasses the fuel assemblies as well as the gaps in between. Consequently, a larger volume is represented by porous media in the second model; hence, a higher frictional flow resistance is introduced in the momentum equations. The conservatism and the safety margins of these models were compared to assess the applicability and the realism of these two models. The three-dimensional model included fewer geometry simplifications and is recommended as it predicted less conservative fuel cladding temperature values, while still assuring the existence of adequate safety margins. (authors)
Flow modeling of flat oval ductwork elbows using computational fluid dynamics
Mahank, T.A.; Mumma, S.A. [Pennsylvania State Univ., University Park, PA (United States)
1997-12-31T23:59:59.000Z
Incompressible turbulent flow fields in heating, ventilating, and air-conditioning (HVAC) elbows were computed using an incompressible, three-dimensional computational fluid dynamics (CFD) solver implementing a {kappa}-{epsilon} turbulence model. Two different geometries were investigated, including 90-degree five-gore hard-bend and easy-bend flat oval elbows. The geometries represent a subset of many configurations analyzed in ASHRAE RP-854, Determination of Duct Fitting Resistance by Numerical Analysis. For each configuration, the zero-length pressure loss coefficient was calculated. The flow was described through contours of velocity and plots of static pressure. The Reynolds number for these flows was held constant at 100,000 based on duct diameter and mean fluid velocity.
Mech 521 Fluid Mechanics Project December 6, 2012 Introduction
Muradoglu, Metin
the open source computational fluid dynamics (CFD) package OpenFOAM to computationally examine supersonic and a bow-shock wave is formed in front of the airfoil. Software and Computer Lab: OpenFOAM is an open source CFD package that is freely available and can be downloaded from its web page www.openfoam
Angelo Frisani; Yassin A. Hassan; Victor M. Ugaz
2010-11-02T23:59:59.000Z
The design of passive heat removal systems is one of the main concerns for the modular very high temperature gas-cooled reactors (VHTR) vessel cavity. The reactor cavity cooling system (RCCS) is a key heat removal system during normal and off-normal conditions. The design and validation of the RCCS is necessary to demonstrate that VHTRs can survive to the postulated accidents. The computational fluid dynamics (CFD) STAR-CCM+/V3.06.006 code was used for three-dimensional system modeling and analysis of the RCCS. A CFD model was developed to analyze heat exchange in the RCCS. The model incorporates a 180-deg section resembling the VHTR RCCS experimentally reproduced in a laboratory-scale test facility at Texas A&M University. All the key features of the experimental facility were taken into account during the numerical simulations. The objective of the present work was to benchmark CFD tools against experimental data addressing the behavior of the RCCS following accident conditions. Two cooling fluids (i.e., water and air) were considered to test the capability of maintaining the RCCS concrete walls' temperature below design limits. Different temperature profiles at the reactor pressure vessel (RPV) wall obtained from the experimental facility were used as boundary conditions in the numerical analyses to simulate VHTR transient evolution during accident scenarios. Mesh convergence was achieved with an intensive parametric study of the two different cooling configurations and selected boundary conditions. To test the effect of turbulence modeling on the RCCS heat exchange, predictions using several different turbulence models and near-wall treatments were evaluated and compared. The comparison among the different turbulence models analyzed showed satisfactory agreement for the temperature distribution inside the RCCS cavity medium and at the standpipes walls. For such a complicated geometry and flow conditions, the tested turbulence models demonstrated that the realizable k-epsilon model with two-layer all y+ wall treatment performs better than the other k-epsilon and k-omega turbulence models when compared to the experimental results and the Reynolds stress transport turbulence model results. A scaling analysis was developed to address the distortions introduced by the CFD model in simulating the physical phenomena inside the RCCS system with respect to the full plant configuration. The scaling analysis demonstrated that both the experimental facility and the CFD model achieve a satisfactory resemblance of the main flow characteristics inside the RCCS cavity region, and convection and radiation heat exchange phenomena are properly scaled from the actual plant.
Dresser, Thomas J.; Dotson, Curtis L.; Fisher, Richard K.; Graf, Michael J.; Richmond, Marshall C.; Rakowski, Cynthia L.; Carlson, Thomas J.; Mathur, Dilip; Heisey, Paul G.
2007-10-10T23:59:59.000Z
This paper, the second part of a 2 part paper, discusses the use of Computational Fluid Dynamics (CFD) to gain further insight into the results of fish release testing conducted to evaluate the modifications made to upgrade Unit 8 at Wanapum Dam. Part 1 discusses the testing procedures and fish passage survival. Grant PUD is working with Voith Siemens Hydro (VSH) and the Pacific Northwest National Laboratory (PNNL) of DOE and Normandeau Associates in this evaluation. VSH has prepared the geometry for the CFD analysis corresponding to the four operating conditions tested with Unit 9, and the 5 operating conditions tested with Unit 8. Both VSH and PNNL have conducting CFD simulations of the turbine intakes, stay vanes, wicket gates, turbine blades and draft tube of the units. Primary objectives of the analyses were: • determine estimates of where the inserted fish passed the turbine components • determine the characteristics of the flow field along the paths calculated for pressure, velocity gradients and acceleration associated with fish sized bodies • determine the velocity gradients at the structures where fish to structure interaction is predicted. • correlate the estimated fish location of passage with observed injuries • correlate the calculated pressure and acceleration with the information recorded with the sensor fish • utilize the results of the analysis to further interpret the results of the testing. This paper discusses the results of the CFD analyses made to assist the interpretation of the fish test results.
Under consideration for publication in J. Fluid Mech. 1 The fluid dynamics of an underfloor air
Linden, Paul F.
Under consideration for publication in J. Fluid Mech. 1 The fluid dynamics of an underfloor air-0411, U.S.A., (Received 30 May 2005) This paper discusses the fluid dynamics of an under floor air. The experiments show that the properties of the system are determined by the entrainment into the plumes
Distributed computational fluid dynamics Karl Jenkins
de Gispert, AdriÃ
of large and complex datasets. Thus, remote access to this information is an integral part of the CFD turbulent combustion pro- cesses is a strong coupling between turbulence, chemical kinetics and heat release provides a route around the departmental firewalls. The clusters run Globus and Condor for remote job
A lattice mesoscopic model of dynamically heterogeneous fluids
A. Lamura; S. Succi
2005-10-04T23:59:59.000Z
We introduce a mesoscopic three-dimensional Lattice Boltzmann Model which attempts to mimick the physical features associated with cage effects in dynamically heterogeneous fluids. To this purpose, we extend the standard Lattice Boltzmann dynamics with self-consistent constraints based on the non-local density of the surrounding fluid. The resulting dynamics exhibits typical features of dynamic heterogeneous fluids, such as non-Gaussian density distributions and long-time relaxation. Due to its intrinsically parallel dynamics, and absence of statistical noise, the method is expected to compute significantly faster than molecular dynamics, Monte Carlo and lattice glass models.
Wendel, M.W.; Siman-Tov, M.
1998-11-01T23:59:59.000Z
The Spallation Neutron Source (SNS) is a high-power accelerator-based pulsed spallation source being designed by a multilaboratory team led by Oak Ridge National Laboratory (ORNL) to achieve high fluxes of neutrons for scientific experiments. Computational fluid dynamics (CFD) is being used to analyze the SNS design. The liquid-mercury target is subjected to the neutronic (internal) heat generation that results from the proton collisions with the mercury nuclei. The liquid mercury simultaneously serves as the neutronic target medium, transports away the heat generated within itself, and cools the metallic target structure. Recirculation and stagnation zones within the target are of particular concern because of the likelihood that they will result in local hot spots. These zones exist because the most feasible target designs include a complete U-turn flow redirection. Although the primary concern is that the target is adequately cooled, the pressure drop from inlet to outlet must also be considered because pressure drop directly affects structural loading and required pumping power. Based on the current design, a three-dimensional CFD model has been developed that includes the stainless steel target structure, the liquid-mercury target flow, and the liquid-mercury cooling jacket that wraps around the nose of the target.
Three-Dimensional Computational Fluid Dynamics Modeling of Solid Oxide Electrolysis Cells and Stacks
Grant Hawkes; James O'Brien; Carl Stoots; Stephen Herring
2008-07-01T23:59:59.000Z
A three-dimensional computational fluid dynamics (CFD) electrochemical model has been created for detailed analysis of a high-temperature electrolysis stack (solid oxide fuel cells operated as electrolyzers). Inlet and outlet plenum flow distributions are discussed. Maldistribution of plena flow show deviations in per-cell operating conditions due to non-uniformity of species concentrations. Models have also been created to simulate experimental conditions and for code validation. Comparisons between model predictions and experimental results are discussed. Mass, momentum, energy, and species conservation and transport are provided via the core features of the commercial CFD code FLUENT. A solid-oxide fuel cell (SOFC) model adds the electrochemical reactions and loss mechanisms and computation of the electric field throughout the cell. The FLUENT SOFC user-defined subroutine was modified for this work to allow for operation in the electrolysis mode. Model results provide detailed profiles of temperature, Nernst potential, operating potential, activation over-potential, anode-side gas composition, cathode-side gas composition, current density and hydrogen production over a range of stack operating conditions. Variations in flow distribution, and species concentration are discussed. End effects of flow and per-cell voltage are also considered. Predicted mean outlet hydrogen and steam concentrations vary linearly with current density, as expected. Contour plots of local electrolyte temperature, current density, and Nernst potential indicate the effects of heat transfer, reaction cooling/heating, and change in local gas composition.
On spurious behavior of CFD simulations
Yee, H.C. [National Aeronautics and Space Administration, Moffett Field, CA (United States). Ames Research Center; Torczynski, J.R. [Sandia National Labs., Albuquerque, NM (United States); Morton, S.A.; Visbal, M.R. [Wright Lab., Wright-Patterson AFB, OH (United States); Sweby, P.K. [Univ. of Reading (United Kingdom)
1997-05-01T23:59:59.000Z
Spurious behavior in underresolved grids and/or semi-implicit temporal discretizations for four computational fluid dynamics (CFD) simulations are studied. The numerical simulations consist of (a) a 1-D chemically relaxed nonequilibrium model, (b) the direct numerical simulation (DNS) of 2-D incompressible flow over a backward facing step, (c) a loosely-coupled approach for a 2-D fluid-structure interaction, and (d) a 3-D compressible unsteady flow simulation of vortex breakdown in delta wings. Using knowledge from dynamical systems theory, various types of spurious behaviors that are numerical artifacts were systematically identified. These studies revealed the various possible dangers of misinterpreting numerical simulation of realistic complex flows that are constrained by the available computing power. In large scale computations underresolved grids, semi-implicit procedures, loosely-coupled implicit procedures, and insufficiently long time integration in DNS are most often unavoidable. Consequently, care must be taken in both computation and in interpretation of the numerical data. The results presented confirm the important role that dynamical systems theory can play in the understanding of the nonlinear behavior of numerical algorithms and in aiding the identification of the sources of numerical uncertainties in CFD.
Ris-R-1453(EN) Optics and Fluid Dynamics
RisÃ¸-R-1453(EN) Optics and Fluid Dynamics Department Annual Progress Report for 2003 Edited by H May 2004 #12;Abstract The Optics and Fluid Dynamics Department performs basic and applied research within three scientific programmes: (1) laser systems and optical materials, (2) optical diagnostics
Ris-R-1399(EN) Optics and Fluid Dynamics
RisÃ¸-R-1399(EN) Optics and Fluid Dynamics Department Annual Progress Report for 2002 Edited by H May 2003 #12;Abstract The Optics and Fluid Dynamics Department performs basic and applied research within three scientific programmes: (1) laser systems and optical materials, (2) optical diagnostics
Ris-R-1314(EN) Optics and Fluid Dynamics
RisÃ¸-R-1314(EN) Optics and Fluid Dynamics Department Annual Progress Report for 2001 Edited by H March 2002 #12;Abstract The Optics and Fluid Dynamics Department performs basic and applied research within three scientific programmes: (1) laser systems and optical materials, (2) optical diagnostics
Ris-P.-715(EN) Optics and Fluid Dynamics
RisÃ¸-P.-715(EN) Optics and Fluid Dynamics Department Annual Progress Report for 1993 Edited by S Research in the Optics and Fluid Dynamics Department is performed within the following two programme areas: optics and continuum physics. In optics the activities are within (a) optical materials, (b) quasi
Optics and Fluid Dynamics Department Intellectual Capital Accounts 1998
Optics and Fluid Dynamics Department Intellectual Capital Accounts 1998 Resources, production and results RISÃ?-R-1108(EN) RisÃ¸ National Laboratory Optics and Fluid Dynamics Department Building 128 P for optical information storage, Â· novel schemes for spatial cryptography, and Â· new models for surface
Optics and Fluid Dynamics ^>*myft Annual Progress Report
Optics and Fluid Dynamics ^>*myft Department Annual Progress Report 1 January - 31 December 1991;Abstract Research in the Optics and Fluid Dynamics Department covers quasi-elas.ic light scattering, optic association. A ? .mmary of activities in 1991 ii presented. Optical diagnostic methods based on quasi
Quantum Mechanical Description of Fluid Dynamics
H. Y. Cui
2001-08-16T23:59:59.000Z
In this paper, we deal with fluid motion in terms of quantum mechanics. Mechanism accounting for the appearance of quantum behavior is discussed.
The Dalles Dam, Columbia River: Spillway Improvement CFD Study
Cook, Chris B.; Richmond, Marshall C.; Serkowski, John A.
2006-06-01T23:59:59.000Z
This report documents development of computational fluid dynamics (CFD) models that were applied to The Dalles spillway for the US Army Corps of Engineers, Portland District. The models have been successfully validated against physical models and prototype data, and are suitable to support biological research and operations management. The CFD models have been proven to provide reliable information in the turbulent high-velocity flow field downstream of the spillway face that is typically difficult to monitor in the prototype. In addition, CFD data provides hydraulic information throughout the solution domain that can be easily extracted from archived simulations for later use if necessary. This project is part of an ongoing program at the Portland District to improve spillway survival conditions for juvenile salmon at The Dalles. Biological data collected at The Dalles spillway have shown that for the original spillway configuration juvenile salmon passage survival is lower than desired. Therefore, the Portland District is seeking to identify operational and/or structural changes that might be implemented to improve fish passage survival. Pacific Northwest National Laboratory (PNNL) went through a sequence of steps to develop a CFD model of The Dalles spillway and tailrace. The first step was to identify a preferred CFD modeling package. In the case of The Dalles spillway, Flow-3D was as selected because of its ability to simulate the turbulent free-surface flows that occur downstream of each spilling bay. The second step in development of The Dalles CFD model was to assemble bathymetric datasets and structural drawings sufficient to describe the dam (powerhouse, non-overflow dam, spillway, fish ladder entrances, etc.) and tailrace. These datasets are documented in this report as are various 3-D graphical representations of The Dalles spillway and tailrace. The performance of the CFD model was then validated for several cases as the third step. The validated model was then applied to address specific SIS design questions. Specifically, the CFD models were used to evaluate flow deflectors, baffle block removal and the effects of spillwalls. The CFD models were also used to evaluate downstream differences at other locations, such as at the Highway 197 bridge piers and Oregon shore islands, due to alterations in spill pattern. CFD model results were analyzed to quantitatively compare impacts of the spillwall that has subsequently been constructed between bays 6 and 7. CFD model results provided detailed information about how the spillwall would impact downstream flow patterns that complemented results from the 1:80 scale physical model. The CFD model was also used to examine relative differences between the juvenile spill pattern used in previous years and the anticipated spill pattern that will be applied once the wall is complete. In addition, the CFD model examined velocity magnitudes over the downstream basalt shelf to investigate potential for erosion under high flow conditions (e.g., 21 kcfs/bay for bays 1 through 6) with the spillwall in place. Several appendices follow the results and discussion sections of this report. These appendices document the large number of CFD simulations that have been performed by PNNL; both spillway improvement study (SIS) related and those performed for related biological tests.
Computational Fluid Dynamics (cfd) Modeling of a Laboratory Scale Coal Gasifier.
Schultheiss, Kiel S
2013-01-01T23:59:59.000Z
?? Furthering gasification technology is an essential part of advancing clean coal technologies. In order to seek insight into the appropriate operations for the formation… (more)
Computational fluid dynamics (CFD) simulations of aerosol in a u-shaped steam generator tube
Longmire, Pamela
2009-05-15T23:59:59.000Z
Department) for all the support I received while researching and writing this dissertation and to the U.S. Nuclear Regulatory Commission, Office of Nuclear Regulatory Research, Division of Systems Analysis and Regulatory Effectiveness, Safety Margins... in PWRs. Table 1 list NPPs where SGTR events have occurred, the date, leakage rate of radioactive material and the cause of the SGTR. NUREG/CR-6365 reports the first SGTR event occurred in 1975 at Point Beach Unit 1, while the most recent event...
Optimization of a high-efficiency jet ejector by using computational fluid dynamic (CFD) software
in a desalination process High-Pressure Motive Steam Heat Exchanger # 1 # 2 Brine Distillate Sea Water # 3 # n-1 # n (1940) - - - 5 DT - 16 Steam-Jet Air Pumps DuPerow and Bossart (1927) - - 6 DT 1.2 DT - 7 Royds-stage ejectors (DeFrate and Hoerl, 1959). source: Perry's chemical engineering handbook; 7th edition, pg. 10
Ullmer, Brygg
PREDICTION OF CUTTINGS BED HEIGHT WITH COMPUTATIONAL FLUID DYNAMICS IN DRILLING HORIZONTAL parameters such as wellbore geometry, pump rate, drilling fluid rheology and density, and maximum drilling Computational Fluid Dynamics methods. Movement, concentration and accumulation of drilled cuttings in non
Hard Sphere Dynamics for Normal and Granular Fluids
James W. Dufty; Aparna Baskaran
2005-03-08T23:59:59.000Z
A fluid of N smooth, hard spheres is considered as a model for normal (elastic collisions) and granular (inelastic collisions) fluids. The potential energy is discontinuous for hard spheres so the pairwise forces are singular and the usual forms of Newtonian and Hamiltonian mechanics do not apply. Nevertheless, particle trajectories in the N particle phase space are well defined and the generators for these trajectories can be identified. The first part of this presentation is a review of the generators for the dynamics of observables and probability densities. The new results presented in the second part refer to applications of these generators to the Liouville dynamics for granular fluids. A set of eigenvalues and eigenfunctions of the generator for this Liouville dynamics is identified in a special "stationary representation". This provides a class of exact solutions to the Liouville equation that are closely related to hydrodynamics for granular fluids.
Predicting aerodynamic characteristic of typical wind turbine airfoils using CFD
Wolfe, W.P. [Sandia National Labs., Albuquerque, NM (United States); Ochs, S.S. [Iowa State Univ., Ames, IA (United States). Aerospace Engineering Dept.
1997-09-01T23:59:59.000Z
An investigation was conducted into the capabilities and accuracy of a representative computational fluid dynamics code to predict the flow field and aerodynamic characteristics of typical wind-turbine airfoils. Comparisons of the computed pressure and aerodynamic coefficients were made with wind tunnel data. This work highlights two areas in CFD that require further investigation and development in order to enable accurate numerical simulations of flow about current generation wind-turbine airfoils: transition prediction and turbulence modeling. The results show that the laminar-to turbulent transition point must be modeled correctly to get accurate simulations for attached flow. Calculations also show that the standard turbulence model used in most commercial CFD codes, the k-e model, is not appropriate at angles of attack with flow separation. 14 refs., 28 figs., 4 tabs.
Gasification CFD Modeling for Advanced Power Plant Simulations
Zitney, S.E.; Guenther, C.P.
2005-09-01T23:59:59.000Z
In this paper we have described recent progress on developing CFD models for two commercial-scale gasifiers, including a two-stage, coal slurry-fed, oxygen-blown, pressurized, entrained-flow gasifier and a scaled-up design of the PSDF transport gasifier. Also highlighted was NETL’s Advanced Process Engineering Co-Simulator for coupling high-fidelity equipment models with process simulation for the design, analysis, and optimization of advanced power plants. Using APECS, we have coupled the entrained-flow gasifier CFD model into a coal-fired, gasification-based FutureGen power and hydrogen production plant. The results for the FutureGen co-simulation illustrate how the APECS technology can help engineers better understand and optimize gasifier fluid dynamics and related phenomena that impact overall power plant performance.
Dynamical ensembles equivalence in fluid mechanics
Giovanni Gallavotti
1996-05-09T23:59:59.000Z
Dissipative Euler and Navier Stokes equations are discussed with the aim of proposing several experiments apt to test the equivalence of dynamical ensembles and the chaotic hypothesis.
Viscous fluid dynamics in Au+Au collisions at RHIC
A. K. Chaudhuri
2008-06-18T23:59:59.000Z
We have studied the space-time evolution of minimally viscous ($\\frac{\\eta}{s}$=0.08) QGP fluid, undergoing boost-invariant longitudinal motion and arbitrary transverse expansion. Relaxation equations for the shear stress tensor components, derived from the phenomenological Israel-Stewart's theory of dissipative relativistic fluid, are solved simultaneously with the energy-momentum conservation equations. Comparison of evolution of ideal and viscous fluid, both initialized under the similar conditions, e.g. same equilibration time, energy density and velocity profile, indicate that in viscous fluid, energy density or temperature of the fluid evolve slowly than in an ideal fluid. Transverse expansion is also more in viscous evolution. We have also studied particle production in viscous dynamics. Compared to ideal dynamics, in viscous dynamics, particle yield at high $p_T$ is increased. Elliptic flow on the other hand decreases. Minimally viscous QGP fluid, initialized at entropy density $s_{ini}$=110 $fm^{-3}$ at the initial time $\\tau_i$=0.6 fm, if freeze-out at temperature $T_F$=130 MeV, explains the centrality dependence of $p_T$ spectra of identified particles. Experimental $p_T$ spectra of $\\pi^-$, $K^+$ and protons in 0-5%, 5-10%, 10-20%, 20-30%, 30-40% and 40-50% Au+Au collisions are well reproduced through out the experimental $p_T$ range. This is in contrast to ideal dynamics, where, the spectra are reproduced only up to $p_T\\approx$1.5 GeV. Minimally viscous QGP fluid, also explain the elliptic flow in mid-central (10-20%, 16-23%, 20-30%) collisions. The minimum bias elliptic flow is also explained. However, the model under-predict/over-predict the elliptic flow in very central/peripheral collisions.
Local structure and dynamics in colloidal fluids and gels
Takehiro Ohtsuka; C. Patrick Royall; Hajime Tanaka
2009-04-17T23:59:59.000Z
Gels in soft-matter systems are an important nonergodic state of matter. We study a colloid-polymer mixture which is quenched by increasing the polymer concentration, from a fluid to a gel. Using confocal microscopy, we study both the static structure and dynamics in three dimensions (3D). Between the dynamically arrested gel and ergodic fluid comprised of isolated particles we find an intermediate 'cluster fluid' state, where the 'bonds' between the colloidal particles have a finite lifetime. The local dynamics are reminiscent of a fluid, while the local structure is almost identical to that of the gel. Simultaneous real-time local structural analysis and particle tracking in 3D at the single-particle level yields the following interesting information. Particles in the clusters move in a highly correlated manner, but, at the same time, exhibit significant dynamical heterogeneity, reflecting the enhanced mobility near the free surface. Deeper quenching eventually leads to a gel state where the 'bond' lifetime exceeds that of the experiment, although the local structure is almost identical to that of the 'cluster fluid'.
Frost Growth CFD Model of an Integrated Active Desiccant Rooftop Unit
Geoghegan, Patrick J [ORNL; Petrov, Andrei Y [ORNL; Vineyard, Edward Allan [ORNL; Zaltash, Abdolreza [ORNL; Linkous, Randall Lee [ORNL
2008-01-01T23:59:59.000Z
A frost growth model is incorporated into a Computational Fluid Dynamics (CFD) simulation of a heat pump by means of a user-defined function in FLUENT, a commercial CFD code. The transient model is applied to the outdoor section of an Integrated Active Desiccant Rooftop (IADR) unit in heating mode. IADR is a hybrid vapor compression and active desiccant unit capable of handling 100% outdoor air (dedicated outdoor air system) or as a total conditioning system, handling both outdoor air and space cooling or heating loads. The predicted increase in flow resistance and loss in heat transfer capacity due to frost build-up are compared to experimental pressure drop readings and thermal imaging. The purpose of this work is to develop a CFD model that is capable of predicting frost growth, an invaluable tool in evaluating the effectiveness of defrost-on-demand cycles.
CFD analysis of laminar oscillating flows
Booten, C. W. Charles W.); Konecni, S. (Snezana); Smith, B. L. (Barton L.); Martin, R. A. (Richard A.)
2001-01-01T23:59:59.000Z
This paper describes a numerical simulations of oscillating flow in a constricted duct and compares the results with experimental and theoretical data. The numerical simulations were performed using the computational fluid dynamics (CFD) code CFX4.2. The numerical model simulates an experimental oscillating flow facility that was designed to test the properties and characteristics of oscillating flow in tapered ducts, also known as jet pumps. Jet pumps are useful devices in thermoacoustic machinery because they produce a secondary pressure that can counteract an unwanted effect called streaming, and significantly enhance engine efficiency. The simulations revealed that CFX could accurately model velocity, shear stress and pressure variations in laminar oscillating flow. The numerical results were compared to experimental data and theoretical predictions with varying success. The least accurate numerical results were obtained when laminar flow approached transition to turbulent flow.
Lopez, A.R.; Gritzo, L.A.; Hassan, B.
1997-06-01T23:59:59.000Z
For the purposes of designing improved Halon-alternative fire suppression strategies for aircraft applications, Computational Fluid Dynamics (CFD) simulations of the air flow, suppressant transport, and air-suppressant mixing within an uncluttered F18 engine nacelle were performed. The release of inert gases from a Solid Propellant Gas Generator (SPGG) was analyzed at two different injection locations in order to understand the effect of injection position on the flow patterns and the mixing of air and suppression agent. An uncluttered engine nacelle was simulated to provide insight into the global flow features as well as to promote comparisons with previous nacelle fire tests and recent water tunnel tests which included little or no clutter. Oxygen concentration levels, fuel/air residence times that would exist if a small fuel leak were present, velocity contours, and streamline patterns are presented inside the engine nacelle. The numerical results show the influence of the gent release location on regions of potential flame extinction due to oxygen inerting and high flame strain. The occurrence of inflow through the exhaust ducts on the aft end of the nacelle is also predicted. As expected, the predicted oxygen concentration levels were consistently higher than the measured levels since a fire was not modeled in this analysis. Despite differences in the conditions of these simulations and the experiments, good agreement was obtained between the CFD predictions and the experimental measurements.
Green Algae as Model Organisms for Biological Fluid Dynamics
Goldstein, Raymond E
2014-01-01T23:59:59.000Z
In the past decade the volvocine green algae, spanning from the unicellular $Chlamydomonas$ to multicellular $Volvox$, have emerged as model organisms for a number of problems in biological fluid dynamics. These include flagellar propulsion, nutrient uptake by swimming organisms, hydrodynamic interactions mediated by walls, collective dynamics and transport within suspensions of microswimmers, the mechanism of phototaxis, and the stochastic dynamics of flagellar synchronization. Green algae are well suited to the study of such problems because of their range of sizes (from 10 $\\mu$m to several millimetres), their geometric regularity, the ease with which they can be cultured and the availability of many mutants that allow for connections between molecular details and organism-level behavior. This review summarizes these recent developments and highlights promising future directions in the study of biological fluid dynamics, especially in the context of evolutionary biology, that can take advantage of these re...
Green Algae as Model Organisms for Biological Fluid Dynamics
Raymond E. Goldstein
2014-09-08T23:59:59.000Z
In the past decade the volvocine green algae, spanning from the unicellular $Chlamydomonas$ to multicellular $Volvox$, have emerged as model organisms for a number of problems in biological fluid dynamics. These include flagellar propulsion, nutrient uptake by swimming organisms, hydrodynamic interactions mediated by walls, collective dynamics and transport within suspensions of microswimmers, the mechanism of phototaxis, and the stochastic dynamics of flagellar synchronization. Green algae are well suited to the study of such problems because of their range of sizes (from 10 $\\mu$m to several millimetres), their geometric regularity, the ease with which they can be cultured and the availability of many mutants that allow for connections between molecular details and organism-level behavior. This review summarizes these recent developments and highlights promising future directions in the study of biological fluid dynamics, especially in the context of evolutionary biology, that can take advantage of these remarkable organisms.
Recycling Krylov subspaces for CFD applications
Amritkar, Amit; ?wirydowicz, Katarzyna; Tafti, Danesh; Ahuja, Kapil
2015-01-01T23:59:59.000Z
The most popular iterative linear solvers in Computational Fluid Dynamics (CFD) calculations are restarted GMRES and BiCGStab. At the beginning of most incompressible flow calculations, the computation time and the number of iterations to converge for the pressure Poisson equation are quite high. In this case, the BiCGStab algorithm, with relatively cheap but non-optimal iterations, may fail to converge for stiff problems. Thus, a more robust algorithm like GMRES, which guarantees monotonic convergence, is preferred. To reduce the large storage requirements of GMRES, a restarted version - GMRES(m) or its variants - is used in CFD applications. However, GMRES(m) can suffer from stagnation or very slow convergence. For this reason, we use the rGCROT method. rGCROT is an algorithm that improves restarted GMRES by recycling a selected subspace of the search space from one restart of GMRES(m) to the next as well as building and recycling this outer vector space from one problem to the next (subsequent time steps i...
Lee, S.
2011-05-17T23:59:59.000Z
The process of recovering the waste in storage tanks at the Savannah River Site (SRS) typically requires mixing the contents of the tank to ensure uniformity of the discharge stream. Mixing is accomplished with one to four dual-nozzle slurry pumps located within the tank liquid. For the work, a Tank 48 simulation model with a maximum of four slurry pumps in operation has been developed to estimate flow patterns for efficient solid mixing. The modeling calculations were performed by using two modeling approaches. One approach is a single-phase Computational Fluid Dynamics (CFD) model to evaluate the flow patterns and qualitative mixing behaviors for a range of different modeling conditions since the model was previously benchmarked against the test results. The other is a two-phase CFD model to estimate solid concentrations in a quantitative way by solving the Eulerian governing equations for the continuous fluid and discrete solid phases over the entire fluid domain of Tank 48. The two-phase results should be considered as the preliminary scoping calculations since the model was not validated against the test results yet. A series of sensitivity calculations for different numbers of pumps and operating conditions has been performed to provide operational guidance for solids suspension and mixing in the tank. In the analysis, the pump was assumed to be stationary. Major solid obstructions including the pump housing, the pump columns, and the 82 inch central support column were included. The steady state and three-dimensional analyses with a two-equation turbulence model were performed with FLUENT{trademark} for the single-phase approach and CFX for the two-phase approach. Recommended operational guidance was developed assuming that local fluid velocity can be used as a measure of sludge suspension and spatial mixing under single-phase tank model. For quantitative analysis, a two-phase fluid-solid model was developed for the same modeling conditions as the single-phase model. The modeling results show that the flow patterns driven by four pump operation satisfy the solid suspension requirement, and the average solid concentration at the plane of the transfer pump inlet is about 12% higher than the tank average concentrations for the 70 inch tank level and about the same as the tank average value for the 29 inch liquid level. When one of the four pumps is not operated, the flow patterns are satisfied with the minimum suspension velocity criterion. However, the solid concentration near the tank bottom is increased by about 30%, although the average solid concentrations near the transfer pump inlet have about the same value as the four-pump baseline results. The flow pattern results show that although the two-pump case satisfies the minimum velocity requirement to suspend the sludge particles, it provides the marginal mixing results for the heavier or larger insoluble materials such as MST and KTPB particles. The results demonstrated that when more than one jet are aiming at the same position of the mixing tank domain, inefficient flow patterns are provided due to the highly localized momentum dissipation, resulting in inactive suspension zone. Thus, after completion of the indexed solids suspension, pump rotations are recommended to avoid producing the nonuniform flow patterns. It is noted that when tank liquid level is reduced from the highest level of 70 inches to the minimum level of 29 inches for a given number of operating pumps, the solid mixing efficiency becomes better since the ratio of the pump power to the mixing volume becomes larger. These results are consistent with the literature results.
Air Ingress Benchmarking with Computational Fluid Dynamics Analysis
1 Air Ingress Benchmarking with Computational Fluid Dynamics Analysis Tieliang Zhai Professor by the US Nuclear Regulatory Commission #12;2 Air Ingress Accident Objectives and Overall Strategy: Depresurization Pure Diffusion Natural Convection Challenging: Natural convection Multi-component Diffusion (air
Air Ingress Benchmarking with Computational Fluid Dynamics Analysis
Air Ingress Benchmarking with Computational Fluid Dynamics Analysis Andrew C. Kadak Department District Beijing, China September 22-24, 2004 Abstract Air ingress accident is a complicated accident scenario is compounded by multiple physical phenomena that are involved in the air ingress event
Fluids as Dynamic Templates for Cytoskeletal Proteins in Plant Cells
J. T. Lofthouse
2008-07-12T23:59:59.000Z
The Dynamic Template model of biological cell membranes and the cytoplasm as spatially organised fluid layers is extended to plant cells, and is shown to offer a feasible shear driven mechanism for the co-alignment of internal and external fibres observed during growth and tropic responses
3D Tomography from Few Projections in Experimental Fluid Dynamics
SchnÃ¶rr, Christoph
3D Tomography from Few Projections in Experimental Fluid Dynamics Stefania Petra, Andreas Schr projections due to both limited optical access to wind and water tunnels and cost S. Petra, C. Schn projection data. The latter are the pixel entries in the recorded 2D images that represent the integration
Long-wave models of thin film fluid dynamics
A. J. Roberts
1994-11-04T23:59:59.000Z
Centre manifold techniques are used to derive rationally a description of the dynamics of thin films of fluid. The derived model is based on the free-surface $\\eta(x,t)$ and the vertically averaged horizontal velocity $\\avu(x,t)$. The approach appears to converge well and has significant differences from conventional depth-averaged models.
Some Mathematical and Numerical Issues in Geophysical Fluid Dynamics and Climate Dynamics
Jianping Li; Shouhong Wang
2007-11-12T23:59:59.000Z
In this article, we address both recent advances and open questions in some mathematical and computational issues in geophysical fluid dynamics (GFD) and climate dynamics. The main focus is on 1) the primitive equations (PEs) models and their related mathematical and computational issues, 2) climate variability, predictability and successive bifurcation, and 3) a new dynamical systems theory and its applications to GFD and climate dynamics.
fjYTiYTvl/f^ Ris-R-674(EN) Optics and Fluid Dynamics
fjYTiYTvl/f^ RisÃ¸-R-674(EN) Optics and Fluid Dynamics Department Annual Progress Report for 1992 #12;Optics and Fluid Dynamics Department AnnualProgressReport for1992 Edited by L. Lading, JJ. Lynov in the Optics and Fluid Dynamics Department is performed within two sections- The Optics Section has activities
Astronomy 202: Astrophysical Gas Dynamics LL = Fluid Mechanics by Landau & Lifshitz
Wurtele, Jonathan
Astronomy 202: Astrophysical Gas Dynamics LL = Fluid Mechanics by Landau & Lifshitz PP = Plasma Fluid Dynamics by D. J. Tritton You should start by reading the Feynman Lectures Vol II, Ch 40 & 41 (Shu Ch. 1) 2. Equations of Gas Dynamics: neutral ideal fluids (LL Ch. 1; esp. Â§1,2,5,6,7,8,10; Shu Ch
The simulation of free surface flows with Computational Fluid Dynamics B. Godderidge1
1 The simulation of free surface flows with Computational Fluid Dynamics B. Godderidge1 A of these applications make their simulation with computational fluid dynamics particularly challenging. The successful Computational fluid dynamics is a powerful and versatile tool for the analysis of flow problems encountered
Fast-Track Design Efforts Using CFD: Bonneville Second Powerhouse
Rakowski, Cynthia L.; Ebner, Laurie L.; Richmond, Marshall C.
2007-10-10T23:59:59.000Z
A set of three-dimensional, computational fluid dynamics (CFD) models were developed and used for the Bonneville Project tailrace to study the impact of a proposed outfall structure on the tailrace hydraulics; these structures were designed to improve the survival of downstream migrant (juvenile) salmon. Flows were simulated by solving the Reynolds-Averaged Navier-Stokes equations together with a two-equation k-epsilon turbulences model in a commercial CFD code. The numerical model was validated using field-measured velocity data. The model results identified undesirable combinations of outfall location and operational scenarios and helped to identify the location in which the outfall structure was built. The numerical model provided a relatively low-cost tool to rapidly simulate and visualize the flow field for multiple proposed outfall locations for a large number of operational scenarios. The visualizations of the results from the CFD model provided insights to hydraulic engineers and fisheries biologists working on the design and placement of the outfall structure.
Experimental and CFD Analysis of Advanced Convective Cooling Systems
Yassin A. Hassan; Victor M. Ugaz
2012-06-27T23:59:59.000Z
The objective of this project is to study the fundamental physical phenomena in the reactor cavity cooling system (RCCS) of very high-temperature reactors (VHTRs). One of the primary design objectives is to assure that RCCS acts as an ultimate heat sink capable of maintaining thermal integrity of the fuel, vessel, and equipment within the reactor cavity for the entire spectrum of postulated accident scenarios. Since construction of full-scale experimental test facilities to study these phenomena is impractical, it is logical to expect that computational fluid dynamics (CFD) simulations will play a key role in the RCCS design process. An important question then arises: To what extent are conventional CFD codes able to accurately capture the most important flow phenomena, and how can they be modified to improve their quantitative predictions? Researchers are working to tackle this problem in two ways. First, in the experimental phase, the research team plans to design and construct an innovative platform that will provide a standard test setting for validating CFD codes proposed for the RCCS design. This capability will significantly advance the state of knowledge in both liquid-cooled and gas-cooled (e.g., sodium fast reactor) reactor technology. This work will also extend flow measurements to micro-scale levels not obtainable in large-scale test facilities, thereby revealing previously undetectable phenomena that will complement the existing infrastructure. Second, in the computational phase of this work, numerical simulation of the flow and temperature profiles will be performed using advanced turbulence models to simulate the complex conditions of flows in critical zones of the cavity. These models will be validated and verified so that they can be implemented into commercially available CFD codes. Ultimately, the results of these validation studies can then be used to enable a more accurate design and safety evaluation of systems in actual nuclear power applications (both during normal operation and accident scenarios).
DRILL-STRING NONLINEAR DYNAMICS ACCOUNTING FOR DRILLING FLUID T. G. Ritto
Boyer, Edmond
DRILL-STRING NONLINEAR DYNAMICS ACCOUNTING FOR DRILLING FLUID T. G. Ritto R. Sampaio thiagoritto Descartes, 77454 Marne-la-VallÃ©e, France Abstract. The influence of the drilling fluid (or mud) on the drill in the analysis of the nonlinear dynamics of a drill-string. The aim of this paper is to investigate how the fluid
The stochastic dynamics of tethered microcantilevers in a viscous fluid
Robbins, Brian A.; Paul, Mark R. [Department of Mechanical Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States); Radiom, Milad; Ducker, William A. [Department of Chemical Engineering, Virginia Tech, Blacksburg, Virginia 24061 (United States); Walz, John Y. [Department of Chemical Engineering, University of Kentucky, Lexington, Kentucky 40506 (United States)
2014-10-28T23:59:59.000Z
We explore and quantify the coupled dynamics of a pair of micron scale cantilevers immersed in a viscous fluid that are also directly tethered to one another at their tips by a spring force. The spring force, for example, could represent the molecular stiffness or elasticity of a biomolecule or material tethered between the cantilevers. We use deterministic numerical simulations with the fluctuation-dissipation theorem to compute the stochastic dynamics of the cantilever pair for the conditions of experiment when driven only by Brownian motion. We validate our approach by comparing directly with experimental measurements in the absence of the tether which shows excellent agreement. Using numerical simulations, we quantify the correlated dynamics of the cantilever pair over a range of tether stiffness. Our results quantify the sensitivity of the auto- and cross-correlations of equilibrium fluctuations in cantilever displacement to the stiffness of the tether. We show that the tether affects the magnitude of the correlations which can be used in a measurement to probe the properties of an attached tethering substance. For the configurations of current interest using micron scale cantilevers in water, we show that the magnitude of the fluid coupling between the cantilevers is sufficiently small such that the influence of the tether can be significant. Our results show that the cross-correlation is more sensitive to tether stiffness than the auto-correlation indicating that a two-cantilever measurement has improved sensitivity when compared with a measurement using a single cantilever.
Fluid dynamics on ultrastatic spacetimes and dual black holes
Dietmar Klemm; Andrea Maiorana
2014-07-09T23:59:59.000Z
We show that the classification of shearless and incompressible stationary fluid flows on ultrastatic manifolds is equivalent to classifying the isometries of the spatial sections. For a flow on R x S$^2$ this leaves only one possibility, since on the 2-sphere all Killing fields are conjugate to each other, and it is well-known that the gravity dual of such a (conformal) fluid is the spherical KNAdS$_4$ black hole. On the other hand, in R x H$^2$ the situation is more complicated, since the isometry group of H$^2$ admits elliptic, parabolic and hyperbolic elements. One might thus ask what the gravity duals of the flows corresponding to these three different cases are. Answering this question is one of the scopes of this paper. In particular we identify the black hole dual to a fluid that is purely translating on the hyperbolic plane. Although this lies within the Carter-Plebanski (CP) class, it has never been studied in the literature before, and represents thus in principle a new black hole solution in AdS$_4$. For a rigidly rotating fluid in R x H$^2$ (holographically dual to the hyperbolic KNAdS$_4$ solution), there is a certain radius where the velocity reaches the speed of light, and thus the fluid can cover only the region within this radius. Quite remarkably, it turns out that the boundary of the hyperbolic KNAdS$_4$ black hole is conformal to exactly that part of R x H$^2$ in which the fluid velocity does not exceed the speed of light. We extend these results to establish a precise mapping between possible flows on ultrastatic spacetimes (with constant curvature spatial sections) and the parameter space of the CP solution. Finally, we show that the alternative description of the hyperbolic KNAdS$_4$ black hole in terms of fluid mechanics on R x S$^2$ or on flat space is dynamical and consists of a contracting or expanding vortex.
CFD Analysis of Core Bypass Phenomena
Richard W. Johnson; Hiroyuki Sato; Richard R. Schultz
2010-03-01T23:59:59.000Z
The U.S. Department of Energy is exploring the potential for the VHTR which will be either of a prismatic or a pebble-bed type. One important design consideration for the reactor core of a prismatic VHTR is coolant bypass flow which occurs in the interstitial regions between fuel blocks. Such gaps are an inherent presence in the reactor core because of tolerances in manufacturing the blocks and the inexact nature of their installation. Furthermore, the geometry of the graphite blocks changes over the lifetime of the reactor because of thermal expansion and irradiation damage. The existence of the gaps induces a flow bias in the fuel blocks and results in unexpected increase of maximum fuel temperature. Traditionally, simplified methods such as flow network calculations employing experimental correlations are used to estimate flow and temperature distributions in the core design. However, the distribution of temperature in the fuel pins and graphite blocks as well as coolant outlet temperatures are strongly coupled with the local heat generation rate within fuel blocks which is not uniformly distributed in the core. Hence, it is crucial to establish mechanistic based methods which can be applied to the reactor core thermal hydraulic design and safety analysis. Computational Fluid Dynamics (CFD) codes, which have a capability of local physics based simulation, are widely used in various industrial fields. This study investigates core bypass flow phenomena with the assistance of commercial CFD codes and establishes a baseline for evaluation methods. A one-twelfth sector of the hexagonal block surface is modeled and extruded down to whole core length of 10.704m. The computational domain is divided vertically with an upper reflector, a fuel section and a lower reflector. Each side of the sector grid can be set as a symmetry boundary
CFD Analysis of Core Bypass Phenomena
Richard W. Johnson; Hiroyuki Sato; Richard R. Schultz
2009-11-01T23:59:59.000Z
The U.S. Department of Energy is exploring the potential for the VHTR which will be either of a prismatic or a pebble-bed type. One important design consideration for the reactor core of a prismatic VHTR is coolant bypass flow which occurs in the interstitial regions between fuel blocks. Such gaps are an inherent presence in the reactor core because of tolerances in manufacturing the blocks and the inexact nature of their installation. Furthermore, the geometry of the graphite blocks changes over the lifetime of the reactor because of thermal expansion and irradiation damage. The existence of the gaps induces a flow bias in the fuel blocks and results in unexpected increase of maximum fuel temperature. Traditionally, simplified methods such as flow network calculations employing experimental correlations are used to estimate flow and temperature distributions in the core design. However, the distribution of temperature in the fuel pins and graphite blocks as well as coolant outlet temperatures are strongly coupled with the local heat generation rate within fuel blocks which is not uniformly distributed in the core. Hence, it is crucial to establish mechanistic based methods which can be applied to the reactor core thermal hydraulic design and safety analysis. Computational Fluid Dynamics (CFD) codes, which have a capability of local physics based simulation, are widely used in various industrial fields. This study investigates core bypass flow phenomena with the assistance of commercial CFD codes and establishes a baseline for evaluation methods. A one-twelfth sector of the hexagonal block surface is modeled and extruded down to whole core length of 10.704m. The computational domain is divided vertically with an upper reflector, a fuel section and a lower reflector. Each side of the one-twelfth grid can be set as a symmetry boundary
Bonneville Project: CFD of the Spillway Tailrace
Rakowski, Cynthia L.; Serkowski, John A.; Richmond, Marshall C.; Romero Gomez, Pedro DJ
2012-11-19T23:59:59.000Z
US Army Corps of Engineers, Portland District (CENWP) operates the Bonneville Lock and Dam Project on the Columbia River. High spill flows that occurred during 2011 moved a large volume of rock from downstream of the spillway apron to the stilling basin and apron. Although 400 cubic yards of rocks were removed from the stilling basin, there are still large volumes of rock downstream of the apron that could, under certain flow conditions, move upstream into the stilling basin. CENWP is investigating operational changes that could be implemented to minimize future movement of rock into the stilling basin. A key analysis tool to develop these operational changes is a computational fluid dynamics (CFD) model of the spillway. A free-surface CFD model of the Bonneville spillway tailrace was developed and applied for four flow scenarios. These scenarios looked at the impact of flow volume and flow distribution on tailrace hydraulics. The simulation results showed that areas of upstream flow existed near the river bed downstream of the apron, on the apron, and within the stilling basin for all flows. For spill flows of 300 kcfs, the cross-stream and downstream extent of the recirculation zones along Cascade and Bradford Island was very dependent on the spill pattern. The center-loaded pattern had much larger recirculation zones than the flat or bi-modal pattern. The lower flow (200 kcfs) with a flat pattern had a very large recirculation zone that extended half way across the channel near the river bed. A single flow scenario (300 kcfs of flow in a relatively flat spill pattern) was further interrogated using Lagrangian particle tracking. The tracked particles (with size and mass) showed the upstream movement of sediments onto the concrete apron and against the vertical wall between the apron and the stilling basin from seed locations downstream of the apron and on the apron.
CFD Validation of Gas Injection into Stagnant Water
Abdou, Ashraf A [ORNL
2007-01-01T23:59:59.000Z
Investigations in the area of two-phase flow at the Oak Ridge National Laboratory's (ORNL) Spallation Neutron Source (SNS) facility are progressing. It is expected that the target vessel lifetime could be extended by introducing gas into the liquid mercury target. As part of an effort to validate the two-phase computational fluid dynamics (CFD) model, simulations and experiments of gas injection in stagnant water have been completed. The volume of fluid (VOF) method as implemented in ANSYS-CFX was used to simulate the unsteady two-phase flow of gas injection into stagnant water. Flow visualization data were obtained with a high-speed camera for the comparison of predicted and measured bubble sizes and shapes at various stages of the bubble growth, detachment, and gravitational rise. The CFD model is validated with these experimental measurements at different gas flow rates. The acoustic waves emitted at the time of detachment and during subsequent oscillations of the bubble were recorded with a microphone. The acoustic signature aspect of this validation is particularly interesting since it has applicability to the injection of gas into liquid mercury, which is opaque.
Battiste, Richard L
2013-12-31T23:59:59.000Z
Methods and apparatus are described for characterizing the temporal-spatial properties of a dynamic fluid front within a mold space while the mold space is being filled with fluid. A method includes providing a mold defining a mold space and having one or more openings into the mold space; heating a plurality of temperature sensors that extend into the mold space; injecting a fluid into th emold space through the openings, the fluid experiencing a dynamic fluid front while filling the mold space with a fluid; and characterizing temporal-spatial properties of the dynamic fluid front by monitoring a termperature of each of the plurality of heated temperature sensors while the mold space is being filled with the fluid. An apparatus includes a mold defining a mold space; one or more openings for introducing a fluid into th emold space and filling the mold space with the fluid, the fluid experiencing a dynamic fluid front while filling the mold space; a plurality of heated temperature sensors extending into the mold space; and a computer coupled to the plurality of heated temperature sensors for characterizing the temporal-spatial properties of the dynamic fluid front.
Battiste, Richard L. (Oak Ridge, TN)
2007-12-25T23:59:59.000Z
Methods and apparatus are described for characterizing the temporal-spatial properties of a dynamic fluid front within a mold space while the mold space is being filled with fluid. A method includes providing a mold defining a mold space and having one or more openings into the mold space; heating a plurality of temperature sensors that extend into the mold space; injecting a fluid into the mold space through the openings, the fluid experiencing a dynamic fluid front while filling the mold space with the fluid; and characterizing temporal-spatial properties of the dynamic fluid front by monitoring a temperature of each of the plurality of heated temperature sensors while the mold space is being filled with the fluid. An apparatus includes a mold defining a mold space; one or more openings for introducing a fluid into the mold space and filling the mold space with the fluid, the fluid experiencing a dynamic fluid front while filling the mold space; a plurality of heated temperature sensors extending into the mold space; and a computer coupled to the plurality of heated temperature sensors for characterizing the temporal-spatial properties of the dynamic fluid front.
Comparison of a semi-analytic and a CFD model uranium combustion to experimental data.
Clarksean, R.
1998-04-01T23:59:59.000Z
Two numerical models were developed and compared for the analysis of uranium combustion and ignition in a furnace. Both a semi-analytical solution and a computational fluid dynamics (CFD) numerical solution were obtained. Prediction of uranium oxidation rates is important for fuel storage applications, fuel processing, and the development of spent fuel metal waste forms. The semi-analytical model was based on heat transfer correlations, a semi-analytical model of flow over a flat surface, and simple radiative heat transfer from the material surface. The CFD model numerically determined the flowfield over the object of interest, calculated the heat and mass transfer to the material of interest, and calculated the radiative heat exchange of the material with the furnace. The semi-analytical model is much less detailed than the CFD model, but yields reasonable results and assists in understanding the physical process. Short computation times allowed the analyst to study numerous scenarios. The CFD model had significantly longer run times, was found to have some physical limitations that were not easily modified, but was better able to yield details of the heat and mass transfer and flow field once code limitations were overcome.
Multi-Phase CFD Modeling of Solid Sorbent Carbon Capture System
Ryan, Emily M.; DeCroix, David; Breault, Ronald W.; Xu, Wei; Huckaby, E. D.; Saha, Kringan; Darteville, Sebastien; Sun, Xin
2013-07-30T23:59:59.000Z
Computational fluid dynamics (CFD) simulations are used to investigate a low temperature post-combustion carbon capture reactor. The CFD models are based on a small scale solid sorbent carbon capture reactor design from ADA-ES and Southern Company. The reactor is a fluidized bed design based on a silica-supported amine sorbent. CFD models using both Eulerian-Eulerian and Eulerian-Lagrangian multi-phase modeling methods are developed to investigate the hydrodynamics and adsorption of carbon dioxide in the reactor. Models developed in both FLUENT® and BARRACUDA are presented to explore the strengths and weaknesses of state of the art CFD codes for modeling multi-phase carbon capture reactors. The results of the simulations show that the FLUENT® Eulerian-Lagrangian simulations (DDPM) are unstable for the given reactor design; while the BARRACUDA Eulerian-Lagrangian model is able to simulate the system given appropriate simplifying assumptions. FLUENT® Eulerian-Eulerian simulations also provide a stable solution for the carbon capture reactor given the appropriate simplifying assumptions.
Multi-phase CFD modeling of solid sorbent carbon capture system
Ryan, E. M.; DeCroix, D.; Breault, Ronald W. [U.S. DOE; Xu, W.; Huckaby, E. David [U.S. DOE
2013-01-01T23:59:59.000Z
Computational fluid dynamics (CFD) simulations are used to investigate a low temperature post-combustion carbon capture reactor. The CFD models are based on a small scale solid sorbent carbon capture reactor design from ADA-ES and Southern Company. The reactor is a fluidized bed design based on a silica-supported amine sorbent. CFD models using both Eulerian–Eulerian and Eulerian–Lagrangian multi-phase modeling methods are developed to investigate the hydrodynamics and adsorption of carbon dioxide in the reactor. Models developed in both FLUENT® and BARRACUDA are presented to explore the strengths and weaknesses of state of the art CFD codes for modeling multi-phase carbon capture reactors. The results of the simulations show that the FLUENT® Eulerian–Lagrangian simulations (DDPM) are unstable for the given reactor design; while the BARRACUDA Eulerian–Lagrangian model is able to simulate the system given appropriate simplifying assumptions. FLUENT® Eulerian–Eulerian simulations also provide a stable solution for the carbon capture reactor given the appropriate simplifying assumptions.
CFD INVESTIGATION OF EXPERIMENTAL DATA PROPOSED TO BE A VALIDATION DATA SET
Richard W. Johnson
2009-07-01T23:59:59.000Z
The U. S. Department of Energy (DOE) is currently supporting the development of a next generation nuclear plant (NGNP). The NGNP is based on the very high temperature reactor (VHTR), which is a Gen. IV gas-cooled reactor concept that will use helium as the coolant. Computational fluid dynamics (CFD) calculations are to be employed to estimate the details of the flow and heat transfer in the lower plenum where the heated coolant empties before exiting the reactor vessel. While it is expected that CFD will be able to provide detailed information about the flow, it must be validated using experimental data. Detailed experimental data have been taken in the INL’s matched index of refraction (MIR) facility of a scaled model of a section of the prismatic VHTR lower plenum. The present article examines the data that were taken to determine the suitability of such data to be a validation data set for CFD calculations. CFD calculations were made to compare with the experimental data to explore potential issues and make recommendations regarding the MIR data.
McGrath, Arran Thomas
2011-01-01T23:59:59.000Z
??A study was carried out into the computational fluid dynamic simulation of bio-oil combustion. Measurements were taken in an empirical burner to obtain information regarding… (more)
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, European Conference on Computational Fluid Dynamics, TU Delft, Delft The Netherland, 2006. D. Lazzara (MIT... Process, No. ... Source: de Weck, Olivier L. - Department...
Leishear, R.; Poirier, M.; Lee, S.; Fowley, M.
2012-06-26T23:59:59.000Z
This paper documents testing methods, statistical data analysis, and a comparison of experimental results to CFD models for blending of fluids, which were blended using a single pump designed with dual opposing nozzles in an eight foot diameter tank. Overall, this research presents new findings in the field of mixing research. Specifically, blending processes were clearly shown to have random, chaotic effects, where possible causal factors such as turbulence, pump fluctuations, and eddies required future evaluation. CFD models were shown to provide reasonable estimates for the average blending times, but large variations -- or scatter -- occurred for blending times during similar tests. Using this experimental blending time data, the chaotic nature of blending was demonstrated and the variability of blending times with respect to average blending times were shown to increase with system complexity. Prior to this research, the variation in blending times caused discrepancies between CFD models and experiments. This research addressed this discrepancy, and determined statistical correction factors that can be applied to CFD models, and thereby quantified techniques to permit the application of CFD models to complex systems, such as blending. These blending time correction factors for CFD models are comparable to safety factors used in structural design, and compensate variability that cannot be theoretically calculated. To determine these correction factors, research was performed to investigate blending, using a pump with dual opposing jets which re-circulate fluids in the tank to promote blending when fluids are added to the tank. In all, eighty-five tests were performed both in a tank without internal obstructions and a tank with vertical obstructions similar to a tube bank in a heat exchanger. These obstructions provided scale models of vertical cooling coils below the liquid surface for a full scale, liquid radioactive waste storage tank. Also, different jet diameters and different horizontal orientations of the jets were investigated with respect to blending. Two types of blending tests were performed. The first set of eighty-one tests blended small quantities of tracer fluids into solution. Data from these tests were statistically evaluated to determine blending times for the addition of tracer solution to tanks, and blending times were successfully compared to Computational Fluid Dynamics (CFD) models. The second set of four tests blended bulk quantities of solutions of different density and viscosity. For example, in one test a quarter tank of water was added to a three quarters of a tank of a more viscous salt solution. In this case, the blending process was noted to significantly change due to stratification of fluids, and blending times increased substantially. However, CFD models for stratification and the variability of blending times for different density fluids was not pursued, and further research is recommended in the area of blending bulk quantities of fluids. All in all, testing showed that CFD models can be effectively applied if statistically validated through experimental testing, but in the absence of experimental validation CFD model scan be extremely misleading as a basis for design and operation decisions.
Coupled computational fluid dynamics and heat transfer analysis of the VHTR lower plenum.
El-Genk, Mohamed S. (University of New Mexico, Albuquerque, NM); Rodriguez, Salvador B.
2010-12-01T23:59:59.000Z
The very high temperature reactor (VHTR) concept is being developed by the US Department of Energy (DOE) and other groups around the world for the future generation of electricity at high thermal efficiency (> 48%) and co-generation of hydrogen and process heat. This Generation-IV reactor would operate at elevated exit temperatures of 1,000-1,273 K, and the fueled core would be cooled by forced convection helium gas. For the prismatic-core VHTR, which is the focus of this analysis, the velocity of the hot helium flow exiting the core into the lower plenum (LP) could be 35-70 m/s. The impingement of the resulting gas jets onto the adiabatic plate at the bottom of the LP could develop hot spots and thermal stratification and inadequate mixing of the gas exiting the vessel to the turbo-machinery for energy conversion. The complex flow field in the LP is further complicated by the presence of large cylindrical graphite posts that support the massive core and inner and outer graphite reflectors. Because there are approximately 276 channels in the VHTR core from which helium exits into the LP and a total of 155 support posts, the flow field in the LP includes cross flow, multiple jet flow interaction, flow stagnation zones, vortex interaction, vortex shedding, entrainment, large variation in Reynolds number (Re), recirculation, and mixing enhancement and suppression regions. For such a complex flow field, experimental results at operating conditions are not currently available. Instead, the objective of this paper is to numerically simulate the flow field in the LP of a prismatic core VHTR using the Sandia National Laboratories Fuego, which is a 3D, massively parallel generalized computational fluid dynamics (CFD) code with numerous turbulence and buoyancy models and simulation capabilities for complex gas flow fields, with and without thermal effects. The code predictions for simpler flow fields of single and swirling gas jets, with and without a cross flow, are validated using reported experimental data and theory. The key processes in the LP are identified using phenomena identification and ranking table (PIRT). It may be argued that a CFD code that accurately simulates simplified, single-effect flow fields with increasing complexity is likely to adequately model the complex flow field in the VHTR LP, subject to a future experimental validation. The PIRT process and spatial and temporal discretizations implemented in the present analysis using Fuego established confidence in the validation and verification (V and V) calculations and in the conclusions reached based on the simulation results. The performed calculations included the helicoid vortex swirl model, the dynamic Smagorinsky large eddy simulation (LES) turbulence model, participating media radiation (PMR), and 1D conjugate heat transfer (CHT). The full-scale, half-symmetry LP mesh used in the LP simulation included unstructured hexahedral elements and accounted for the graphite posts, the helium jets, the exterior walls, and the bottom plate with an adiabatic outer surface. Results indicated significant enhancements in heat transfer, flow mixing, and entrainment in the VHTR LP when using swirling inserts at the exit of the helium flow channels into the LP. The impact of using various swirl angles on the flow mixing and heat transfer in the LP is qualified, including the formation of the central recirculation zone (CRZ), and the effect of LP height. Results also showed that in addition to the enhanced mixing, the swirling inserts result in negligible additional pressure losses and are likely to eliminate the formation of hot spots.
Fluid Dynamics of Carbon Dioxide Disposal into Saline Aquifers
Garcia, Julio Enrique
2003-12-18T23:59:59.000Z
Injection of carbon dioxide (CO{sub 2}) into saline aquifers has been proposed as a means to reduce greenhouse gas emissions (geological carbon sequestration). Large-scale injection of CO{sub 2} will induce a variety of coupled physical and chemical processes, including multiphase fluid flow, fluid pressurization and changes in effective stress, solute transport, and chemical reactions between fluids and formation minerals. This work addresses some of these issues with special emphasis given to the physics of fluid flow in brine formations. An investigation of the thermophysical properties of pure carbon dioxide, water and aqueous solutions of CO{sub 2} and NaCl has been conducted. As a result, accurate representations and models for predicting the overall thermophysical behavior of the system CO{sub 2}-H{sub 2}O-NaCl are proposed and incorporated into the numerical simulator TOUGH2/ECO{sub 2}. The basic problem of CO{sub 2} injection into a radially symmetric brine aquifer is used to validate the results of TOUGH2/ECO2. The numerical simulator has been applied to more complex flow problem including the CO{sub 2} injection project at the Sleipner Vest Field in the Norwegian sector of the North Sea and the evaluation of fluid flow dynamics effects of CO{sub 2} injection into aquifers. Numerical simulation results show that the transport at Sleipner is dominated by buoyancy effects and that shale layers control vertical migration of CO{sub 2}. These results are in good qualitative agreement with time lapse surveys performed at the site. High-resolution numerical simulation experiments have been conducted to study the onset of instabilities (viscous fingering) during injection of CO{sub 2} into saline aquifers. The injection process can be classified as immiscible displacement of an aqueous phase by a less dense and less viscous gas phase. Under disposal conditions (supercritical CO{sub 2}) the viscosity of carbon dioxide can be less than the viscosity of the aqueous phase by a factor of 15. Because of the lower viscosity, the CO{sub 2} displacement front will have a tendency towards instability. Preliminary simulation results show good agreement between classical instability solutions and numerical predictions of finger growth and spacing obtained using different gas/liquid viscosity ratios, relative permeability and capillary pressure models. Further studies are recommended to validate these results over a broader range of conditions.
Climate dynamics and fluid mechanics: Natural variability and related uncertainties
Michael Ghil; Mickaël D. Chekroun; Eric Simonnet
2010-06-15T23:59:59.000Z
The purpose of this review-and-research paper is twofold: (i) to review the role played in climate dynamics by fluid-dynamical models; and (ii) to contribute to the understanding and reduction of the uncertainties in future climate-change projections. To illustrate the first point, we focus on the large-scale, wind-driven flow of the mid-latitude oceans which contribute in a crucial way to Earth's climate, and to changes therein. We study the low-frequency variability (LFV) of the wind-driven, double-gyre circulation in mid-latitude ocean basins, via the bifurcation sequence that leads from steady states through periodic solutions and on to the chaotic, irregular flows documented in the observations. This sequence involves local, pitchfork and Hopf bifurcations, as well as global, homoclinic ones. The natural climate variability induced by the LFV of the ocean circulation is but one of the causes of uncertainties in climate projections. Another major cause of such uncertainties could reside in the structural instability in the topological sense, of the equations governing climate dynamics, including but not restricted to those of atmospheric and ocean dynamics. We propose a novel approach to understand, and possibly reduce, these uncertainties, based on the concepts and methods of random dynamical systems theory. As a very first step, we study the effect of noise on the topological classes of the Arnol'd family of circle maps, a paradigmatic model of frequency locking as occurring in the nonlinear interactions between the El Nino-Southern Oscillations (ENSO) and the seasonal cycle. It is shown that the maps' fine-grained resonant landscape is smoothed by the noise, thus permitting their coarse-grained classification. This result is consistent with stabilizing effects of stochastic parametrization obtained in modeling of ENSO phenomenon via some general circulation models.
Boyer, Edmond
Identification of an average temperature and a dynamical pressure in a multitemperature mixture pressure even if the fluids have a zero bulk viscosity. The nonequilib- rium dynamical pressure can
Nonlinear dynamics of magnetohydrodynamic flows of heavy fluid over an arbitrary surface
equations system for heavy fluid over an arbitrary surface in shallow water approximation is studied to the study of nonlinear flows of heavy fluid described by the shallow water magnetohydrodynamic equations1 Nonlinear dynamics of magnetohydrodynamic flows of heavy fluid over an arbitrary surface
Navarrete, R.C.; Cawiezel, K.E.; Constien, V.G. [Dowell Schlumberger, Tulsa, OK (United States)
1996-08-01T23:59:59.000Z
A study of the dynamic fluid loss of hydraulic fracturing fluids under realistic shear conditions is presented. During a hydraulic fracturing treatment, a polymeric solution is pumped under pressure down the well to create and propagate a fracture. Part of the fluid leaks into the rock formation, leaving a skin layer of polymer or polymer filter cake, at the rock surface or in the pore space. This study focuses on the effects of shear rate and permeability on dynamic fluid-loss behavior of crosslinked and linear fracturing gels. Previous studies of dynamic fluid loss have mainly been with low-permeability cores and constant shear rates. Here, the effect of shear history and fluid-loss additive on the dynamic leakoff of high-permeability cores is examined.
Computational Fluid Dynamics Modeling of a Lithium/Thionyl Chloride Battery with Electrolyte Flow
Wang, Chao-Yang
Computational Fluid Dynamics Modeling of a Lithium/Thionyl Chloride Battery with Electrolyte Flow W.B. Gu and C.Y. Wang GATE Center of Excellence for Advanced Energy Storage Department of Mechanical are performed using a finite volume method of computational fluid dynamics. The predicted discharge curves
Optics and Fluid Dynamics Ris-R-1100(EN) Annual Progress Report for 1998
Optics and Fluid Dynamics RisÃ¸-R-1100(EN) Department Annual Progress Report for 1998 Edited by S May 1999 #12;2 RisÃ¸-R-1100(EN) Abstract Research in the Optics and Fluid Dynamics Department has been performed within the following three programme areas: (1) optical materials, (2) optical diagnostics
Optics and Fluid Dynamics Ris-R-1227(EN) Annual Progress Report for 2000
Optics and Fluid Dynamics RisÃ¸-R-1227(EN) Department Annual Progress Report for 2000 Edited by S;2 RisÃ¸-R-1227(EN) Abstract The Optics and Fluid Dynamics Department performs basic and applied research within three scientific programmes: (1) optical materials, (2) optical diagnostics and information
Optics and Fluid Dynamics Ris-R-1157(EN) Annual Progress Report for 1999
Optics and Fluid Dynamics RisÃ¸-R-1157(EN) Department Annual Progress Report for 1999 Edited by S;2 RisÃ¸-R-1157(EN) Abstract The Optics and Fluid Dynamics Department performs basic and applied research within the three programmes: (1) optical materials, (2) optical diagnostics and information processing
Scaling studies and conceptual experiment designs for NGNP CFD assessment
D. M. McEligot; G. E. McCreery
2004-11-01T23:59:59.000Z
The objective of this report is to document scaling studies and conceptual designs for flow and heat transfer experiments intended to assess CFD codes and their turbulence models proposed for application to prismatic NGNP concepts. The general approach of the project is to develop new benchmark experiments for assessment in parallel with CFD and coupled CFD/systems code calculations for the same geometry. Two aspects of the complex flow in an NGNP are being addressed: (1) flow and thermal mixing in the lower plenum ("hot streaking" issue) and (2) turbulence and resulting temperature distributions in reactor cooling channels ("hot channel" issue). Current prismatic NGNP concepts are being examined to identify their proposed flow conditions and geometries over the range from normal operation to decay heat removal in a pressurized cooldown. Approximate analyses have been applied to determine key non-dimensional parameters and their magnitudes over this operating range. For normal operation, the flow in the coolant channels can be considered to be dominant turbulent forced convection with slight transverse property variation. In a pressurized cooldown (LOFA) simulation, the flow quickly becomes laminar with some possible buoyancy influences. The flow in the lower plenum can locally be considered to be a situation of multiple hot jets into a confined crossflow -- with obstructions. Flow is expected to be turbulent with momentumdominated turbulent jets entering; buoyancy influences are estimated to be negligible in normal full power operation. Experiments are needed for the combined features of the lower plenum flows. Missing from the typical jet experiments available are interactions with nearby circular posts and with vertical posts in the vicinity of vertical walls - with near stagnant surroundings at one extreme and significant crossflow at the other. Two types of heat transfer experiments are being considered. One addresses the "hot channel" problem, if necessary. The second type will treat heated jets entering a model plenum. Unheated MIR (Matched-Index-of-Refraction) experiments are first steps when the geometry is complicated. One does not want to use a computational technique which will not even handle constant properties properly. The purpose of the fluid dynamics experiments is to develop benchmark databases for the assessment of CFD solutions of the momentum equations, scalar mixing and turbulence models for typical NGNP plenum geometries in the limiting case of negligible buoyancy and constant fluid properties. As indicated by the scaling studies, in normal full power operation of a typical NGNP conceptual design, buoyancy influences should be negligible in the lower plenum. The MIR experiment will simulate flow features of the paths of jets as they mix in flowing through the array of posts in a lower plenum en route to the single exit duct. Conceptual designs for such experiments are described.
Computational fluid dynamics modeling of two-phase flow in a BWR fuel assembly. Final CRADA Report.
Tentner, A.; Nuclear Engineering Division
2009-10-13T23:59:59.000Z
A direct numerical simulation capability for two-phase flows with heat transfer in complex geometries can considerably reduce the hardware development cycle, facilitate the optimization and reduce the costs of testing of various industrial facilities, such as nuclear power plants, steam generators, steam condensers, liquid cooling systems, heat exchangers, distillers, and boilers. Specifically, the phenomena occurring in a two-phase coolant flow in a BWR (Boiling Water Reactor) fuel assembly include coolant phase changes and multiple flow regimes which directly influence the coolant interaction with fuel assembly and, ultimately, the reactor performance. Traditionally, the best analysis tools for this purpose of two-phase flow phenomena inside the BWR fuel assembly have been the sub-channel codes. However, the resolution of these codes is too coarse for analyzing the detailed intra-assembly flow patterns, such as flow around a spacer element. Advanced CFD (Computational Fluid Dynamics) codes provide a potential for detailed 3D simulations of coolant flow inside a fuel assembly, including flow around a spacer element using more fundamental physical models of flow regimes and phase interactions than sub-channel codes. Such models can extend the code applicability to a wider range of situations, which is highly important for increasing the efficiency and to prevent accidents.
Baosheng Jin; Rui Xiao; Zhongyi Deng; Qilei Song [Southeast University (China). Key Laboratory of Clean Coal Power Generation and Combustion Technology of Ministry of Education
2009-07-01T23:59:59.000Z
To concentrate CO{sub 2} in combustion processes by efficient and energy-saving ways is a first and very important step for its sequestration. Chemical looping combustion (CLC) could easily achieve this goal. A chemical-looping combustion system consists of a fuel reactor and an air reactor. Two reactors in the form of interconnected fluidized beds are used in the process: (1) a fuel reactor where the oxygen carrier is reduced by reaction with the fuel, and (2) an air reactor where the reduced oxygen carrier from the fuel reactor is oxidized with air. The outlet gas from the fuel reactor consists of CO{sub 2} and H{sub 2}O, while the outlet gas stream from the air reactor contains only N{sub 2} and some unused O{sub 2}. The water in combustion products can be easily removed by condensation and pure carbon dioxide is obtained without any loss of energy for separation. Until now, there is little literature about mathematical modeling of chemical-looping combustion using the computational fluid dynamics (CFD) approach. In this work, the reaction kinetic model of the fuel reactor (CaSO{sub 4}+ H{sub 2}) is developed by means of the commercial code FLUENT and the effects of partial pressure of H{sub 2} (concentration of H{sub 2}) on chemical looping combustion performance are also studied. The results show that the concentration of H{sub 2} could enhance the CLC performance.
HYDRA, A finite element computational fluid dynamics code: User manual
Christon, M.A.
1995-06-01T23:59:59.000Z
HYDRA is a finite element code which has been developed specifically to attack the class of transient, incompressible, viscous, computational fluid dynamics problems which are predominant in the world which surrounds us. The goal for HYDRA has been to achieve high performance across a spectrum of supercomputer architectures without sacrificing any of the aspects of the finite element method which make it so flexible and permit application to a broad class of problems. As supercomputer algorithms evolve, the continuing development of HYDRA will strive to achieve optimal mappings of the most advanced flow solution algorithms onto supercomputer architectures. HYDRA has drawn upon the many years of finite element expertise constituted by DYNA3D and NIKE3D Certain key architectural ideas from both DYNA3D and NIKE3D have been adopted and further improved to fit the advanced dynamic memory management and data structures implemented in HYDRA. The philosophy for HYDRA is to focus on mapping flow algorithms to computer architectures to try and achieve a high level of performance, rather than just performing a port.
Reimers, Martin
M Kleven1,2 , MC Melaaen2 , M Reimers3 , JS RÃ¸tnes4,5 , L Aurdal5,6 , PG Djupesland7 ABSTRACT Nasal
On the dynamics of magnetic fluids in magnetic resonance imaging
Cantillon-Murphy, Pádraig J
2008-01-01T23:59:59.000Z
The hydrodynamics of magnetic fluids, often termed ferrofluids, has been an active area of research since the mid 1960s. However, it is only in the past twenty years that these fluids have begun to be used in magnetic ...
Benjamin D. Goddard; Andreas Nold; Nikos Savva; Grigorios A. Pavliotis; Serafim Kalliadasis
2012-08-08T23:59:59.000Z
We study the dynamics of a colloidal fluid including inertia and hydrodynamic interactions, two effects which strongly influence the non-equilibrium properties of the system. We derive a general dynamical density functional theory (DDFT) which shows very good agreement with full Langevin dynamics. In suitable limits, we recover existing DDFTs and a Navier-Stokes-like equation with additional non-local terms.
Fluid Dynamics Research 33 (2003) 333356 Leapfrogging vortex rings: Hamiltonian structure, geometric
Shashikanth, Banavara N.
2003-01-01T23:59:59.000Z
Fluid Dynamics Research 33 (2003) 333356 Leapfrogging vortex rings: Hamiltonian structure that if the rings are modeled as coaxial circular ÿlaments, their dynamics and Hamil- tonian structure is derivable of Mechanical Engineering, New Mexico State University, Las Cruces, NM 88003, USA b Control and Dynamical
FLUID DYNAMICAL AND MODELING ISSUES OF CHEMICAL FLOODING FOR ENHANCED OIL RECOVERY
Daripa, Prabir
FLUID DYNAMICAL AND MODELING ISSUES OF CHEMICAL FLOODING FOR ENHANCED OIL RECOVERY Prabir Daripa developed flows in enhanced oil recovery (EOR). In a recent exhaustive study [Transport in Porous Media, 93 fluid flows that occur in porous media during tertiary dis- placement process of chemical enhanced oil
Fairman, Randall S. (Randall Scott), 1967-
2002-01-01T23:59:59.000Z
An analysis of current computational fluid dynamics capabilities in predicting mean lift forces for two dimensional foils is conducted. It is shown that both integral boundary layer theory and Reynolds Averaged Navier ...
Parallel Simulation of Subsonic Fluid Dynamics on a Cluster of Workstations
Skordos, Panayotis A.
1995-12-01T23:59:59.000Z
An effective approach of simulating fluid dynamics on a cluster of non- dedicated workstations is presented. The approach uses local interaction algorithms, small communication capacity, and automatic migration of parallel ...
Vortex in a relativistic perfect isentropic fluid and Nambu Goto dynamics
B. Boisseau
1999-11-26T23:59:59.000Z
By a weak deformation of the cylindrical symmetry of the potential vortex in a relativistic perfect isentropic fluid, we study the possible dynamics of the central line of this vortex. In "stiff" material the Nanbu-Goto equations are obtained
A Mechanical Fluid-Dynamical Model For Ground Movements At Campi...
Mechanical Fluid-Dynamical Model For Ground Movements At Campi Flegrei Caldera Jump to: navigation, search OpenEI Reference LibraryAdd to library Journal Article: A Mechanical...
Nonequilibrium molecular dynamics simulations of confined fluids in contact with the bulk
Zhang, Luzheng
Nonequilibrium molecular dynamics simulations of confined fluids in contact with the bulk Luzheng Zhang, Ramkumar Balasundaram,a) and Stevin H. Gehrke Department of Chemical Engineering, Kansas State University, Manhattan, Kansas 66506 Shaoyi Jiangb) Department of Chemical Engineering, University
Infiltration Heat Recovery in Building Walls: Computational Fluid Dynamics Investigations Results
LBNL-51324 Infiltration Heat Recovery in Building Walls: Computational Fluid Dynamics leading to partial recovery of heat conducted through the wall. The Infiltration Heat Recovery (IHR) factor was introduced to quantify the heat recovery and correct the conventional calculations
A CFD-based wind solver for a fast response transport and dispersion model
Gowardhan, Akshay A [Los Alamos National Laboratory; Brown, Michael J [Los Alamos National Laboratory; Pardyjak, Eric R [UNIV OF UTAH; Senocak, Inanc [BOISE STATE UNIV
2010-01-01T23:59:59.000Z
In many cities, ambient air quality is deteriorating leading to concerns about the health of city inhabitants. In urban areas with narrow streets surrounded by clusters of tall buildings, called street canyons, air pollution from traffic emissions and other sources is difficult to disperse and may accumulate resulting in high pollutant concentrations. For various situations, including the evacuation of populated areas in the event of an accidental or deliberate release of chemical, biological and radiological agents, it is important that models should be developed that produce urban flow fields quickly. For these reasons it has become important to predict the flow field in urban street canyons. Various computational techniques have been used to calculate these flow fields, but these techniques are often computationally intensive. Most fast response models currently in use are at a disadvantage in these cases as they are unable to correlate highly heterogeneous urban structures with the diagnostic parameterizations on which they are based. In this paper, a fast and reasonably accurate computational fluid dynamics (CFD) technique that solves the Navier-Stokes equations for complex urban areas has been developed called QUIC-CFD (Q-CFD). This technique represents an intermediate balance between fast (on the order of minutes for a several block problem) and reasonably accurate solutions. The paper details the solution procedure and validates this model for various simple and complex urban geometries.
Simulation of Complex Fluids using Dissipative Particle Dynamics
... Dynamics Abstract: Dissipative Particle Dynamics (DPD) is a relatively new mesoscopic method particularly suitable for simulating biopolymers. It is a coarsed ...
Isomorphic classical molecular dynamics model for an excess electronin a supercritical fluid
Miller III, Thomas F.
2008-08-04T23:59:59.000Z
Ring polymer molecular dynamics (RPMD) is used to directly simulate the dynamics of an excess electron in a supercritical fluid over a broad range of densities. The accuracy of the RPMD model is tested against numerically exact path integral statistics through the use of analytical continuation techniques. At low fluid densities, the RPMD model substantially underestimates the contribution of delocalized states to the dynamics of the excess electron. However, with increasing solvent density, the RPMD model improves, nearly satisfying analytical continuation constraints at densities approaching those of typical liquids. In the high density regime, quantum dispersion substantially decreases the self-diffusion of the solvated electron. In this regime where the dynamics of the electron is strongly coupled to the dynamics of the atoms in the fluid, trajectories that can reveal diffusive motion of the electron are long in comparison to {beta}{h_bar}.
Standard Problems for CFD Validation for NGNP - Status Report
Richard W. Johnson; Richard R. Schultz
2010-08-01T23:59:59.000Z
The U.S. Department of Energy (DOE) is conducting research and development to support the resurgence of nuclear power in the United States for both electrical power generation and production of process heat required for industrial processes such as the manufacture of hydrogen for use as a fuel in automobiles. The project is called the Next Generation Nuclear Plant (NGNP) Project, which is based on a Generation IV reactor concept called the very high temperature reactor (VHTR). The VHTR will be of the prismatic or pebble bed type; the former is considered herein. The VHTR will use helium as the coolant at temperatures ranging from 250°C to perhaps 1000°C. While computational fluid dynamics (CFD) has not previously been used for the safety analysis of nuclear reactors in the United States, it is being considered for existing and future reactors. It is fully recognized that CFD simulation codes will have to be validated for flow physics reasonably close to actual fluid dynamic conditions expected in normal operational and accident situations. The “Standard Problem” is an experimental data set that represents an important physical phenomenon or phenomena, whose selection is based on a phenomena identification and ranking table (PIRT) for the reactor in question. It will be necessary to build a database that contains a number of standard problems for use to validate CFD and systems analysis codes for the many physical problems that will need to be analyzed. The first two standard problems that have been developed for CFD validation consider flow in the lower plenum of the VHTR and bypass flow in the prismatic core. Both involve scaled models built from quartz and designed to be installed in the INL’s matched index of refraction (MIR) test facility. The MIR facility employs mineral oil as the working fluid at a constant temperature. At this temperature, the index of refraction of the mineral oil is the same as that of the quartz. This provides an advantage to the optics used for data gathering. Particle image velocimetry (PIV) is used to take the data. The first standard problem represents several flow physics expected to be present in the lower plenum of the prismatic VHTR. In the lower plenum, heated helium coolant in the form of jets issues downward into the plenum and is then forced to turn ninety degrees and flow toward the exit duct. The lower plenum is filled with cylindrical graphite posts that hold up the core. Figure S-1 provides a plan view of the lower plenum. The red circles represent support posts holding up columns of heated blocks. Grey circles represent support posts under columns of reflector blocks. Helium enters the lower plenum at the junctions of the hexagonal blocks.
Dynamics of non-minimally coupled perfect fluids
Bettoni, Dario
2015-01-01T23:59:59.000Z
We present a general formulation of the theory for a non-minimally coupled perfect fluid in which both conformal and disformal couplings are present. We discuss how such non-minimal coupling is compatible with the assumptions of a perfect fluid and derive both the Einstein and the fluid equations for such model. We found that, while the Euler equation is significantly modified with the introduction of an extra force related to the local gradients of the curvature, the continuity equation is unaltered, thus allowing for the definition of conserved quantities along the fluid flow. As an application to cosmology and astrophysics we compute the effects of the non-minimal coupling on a Friedmann--Lema\\^itre--Robertson--Walker background metric and on the Newtonian limit of our theory.
Petrov type I Condition and Dual Fluid Dynamics
Rong-Gen Cai; Li Li; Qing Yang; Yun-Long Zhang
2014-03-17T23:59:59.000Z
Recently Lysov and Strominger [arXiv:1104.5502] showed that imposing Petrov type I condition on a $(p+1)$-dimensional timelike hypersurface embedded in a $(p+2)$-dimensional vacuum Einstein gravity reduces the degrees of freedom in the extrinsic curvature of the hypersurface to that of a fluid on the hypersurface, and that the leading-order Einstein constraint equations in terms of the mean curvature of the embedding give the incompressible Navier-Stokes equations of the dual fluid. In this paper we show that the non-relativistic fluid dual to vacuum Einstein gravity does not satisfy the Petrov type I condition at next order, unless additional constraint such as the irrotational condition is added. In addition, we show that this procedure can be inversed to derive the non-relativistic hydrodynamics with higher order corrections through imposing the Petrov type I condition, and that some second order transport coefficients can be extracted, but the dual "Petrov type I fluid" does not match the dual fluid constructed from the geometry of vacuum Einstein gravity in the non-relativistic limit. We discuss the procedure both on the finite cutoff surface via the non-relativistic hydrodynamic expansion and on the highly accelerated surface via the near horizon expansion.
The Lagrangian dynamics of thermal tracer particles in Navier-Stokes fluids
Massimo Tessarotto; Claudio Asci; Claudio Cremaschini; Alessandro Soranzo; Marco Tessarotto; Gino Tironi
2012-03-17T23:59:59.000Z
A basic issue for Navier-Stokes (NS) fluids is their characterization in terms of the so-called NS phase-space classical dynamical system, which provides a mathematical model for the description of the dynamics of infinitesimal (or i\\textit{deal}) tracer particles in these fluids. The goal of this paper is to analyze the properties of a particular subset of solutions of the NS dynamical system, denoted as \\textit{thermal tracer particles} (TTPs), whose states are determined uniquely by the NS fluid fields. Applications concerning both deterministic and stochastic NS fluids are pointed out. In particular, in both cases it is shown that in terms of the ensemble of TTPs a statistical description of NS fluids can be formulated. In the case of stochastic fluids this feature permits to uniquely establish the corresponding Langevin and Fokker-Planck dynamics. Finally, the relationship with the customary statistical treatment of hydrodynamic turbulence (HT) is analyzed and a solution to the closure problem for the statistical description of HT is proposed.
D)TT(^!rf5\\\\ "bKtSOOO&i. Ris-R-793(EN) Optics and Fluid Dynamics
D)TT(^!rf5\\\\ "bKtSOOO&i. RisÃ¸-R-793(EN) Optics and Fluid Dynamics Department Annual Progress Report, Denmark January 1995 #12;Optics and Fluid Dynamics Department Annual Progress Report for 1994 Edited by S;Abstract Research in the Optics and Fiuid Dynamics Department is performed within the following two
Zevenhoven, Ron
transferExample: stationary heat transfer Stationary heat transfer, 2-D (Laplace eq'n): with a grid fluid flow (and heat,(and heat, massmass transfer)transfer) ((lecturelecture 4 of 5)4 of 5) Ron #2 -- rzrz Example: stationary heat transferExample: stationary heat transferExample: stationary heat
Numerical implication of Riemann problem theory for fluid dynamics
Menikoff, R.
1988-01-01T23:59:59.000Z
The Riemann problem plays an important role in understanding the wave structure of fluid flow. It is also crucial step in some numerical algorithms for accurately and efficiently computing fluid flow; Godunov method, random choice method, and from tracking method. The standard wave structure consists of shock and rarefaction waves. Due to physical effects such as phase transitions, which often are indistinguishable from numerical errors in an equation of state, anomalkous waves may occur, ''rarefaction shocks'', split waves, and composites. The anomalous waves may appear in numerical calculations as waves smeared out by either too much artificial viscosity or insufficient resolution. In addition, the equation of state may lead to instabilities of fluid flow. Since these anomalous effects due to the equation of state occur for the continuum equations, they can be expected to occur for all computational algorithms. The equation of state may be characterized by three dimensionless variables: the adiabatic exponent ..gamma.., the Grueneisen coefficient GAMMA, and the fundamental derivative G. The fluid flow anomalies occur when inequalities relating these variables are violated. 18 refs.
Dynamic dielectric response of electrorheological fluids in drag and pressure flow
B. Horváth; I. Szalai
2014-12-30T23:59:59.000Z
We have determined the response time of dilute electrorheological fluids (ER) in drag flow, in pressure-driven flow, and in the quiescent state from the dynamic dielectric response. The dependence of the response times on the electric field strength, the shear rate, and the flow velocity were investigated. In the case of ER fluids in drag flow, the response times were also determined from the stress response of the fluid measured simultaneously with the dielectric properties. Comparing the dielectric and rheological response times measured at the same conditions, a significant discrepancy was found, which was attributed to the different instrumental response times of the employed methods. The dielectric permittivity of the quiescent ER fluid was estimated on the basis of formulas derived from the Clausius-Mossotti equation. This simple theoretical model was extended and applied to ER fluids under shear to evaluate the experimental dielectric results.
N.D. Francis, Jr; M.T. Itamura; S.W. Webb; D.L. James
2002-10-01T23:59:59.000Z
The objective of this heat transfer and fluid flow study is to assess the ability of a computational fluid dynamics (CFD) code to reproduce the experimental results, numerical simulation results, and heat transfer correlation equations developed in the literature for natural convection heat transfer within the annulus of horizontal concentric cylinders. In the literature, a variety of heat transfer expressions have been developed to compute average equivalent thermal conductivities. However, the expressions have been primarily developed for very small inner and outer cylinder radii and gap-widths. In this comparative study, interest is primarily focused on large gap widths (on the order of half meter or greater) and large radius ratios. From the steady-state CFD analysis it is found that the concentric cylinder models for the larger geometries compare favorably to the results of the Kuehn and Goldstein correlations in the Rayleigh number range of about 10{sup 5} to 10{sup 8} (a range that encompasses the laminar to turbulent transition). For Rayleigh numbers greater than 10{sup 8}, both numerical simulations and experimental data (from the literature) are consistent and result in slightly lower equivalent thermal conductivities than those obtained from the Kuehn and Goldstein correlations.
No-Go Theorems Face Fluid-Dynamical Theories for Quantum Mechanics
Louis Vervoort
2014-06-16T23:59:59.000Z
Recent experiments on fluid-dynamical systems have revealed a series of striking quantum-like features of these macroscopic systems, thus reviving the quest to describe quantum mechanics by classical, in particular fluid-dynamical, theories. However, it is generally admitted that such an endeavor is impossible, on the basis of the 'no-go' theorems of Bell and Kochen-Specker. Here we show that such theorems are inoperative for fluid-dynamical models, even if these are local. Such models appear to violate one of the premises of both theorems, and can reproduce the quantum correlation of the Bell experiment. Therefore the statement that 'local hidden-variable theories are impossible' appears to be untenable for theories just slightly more general than originally envisaged by Bell. We also discuss experimental implications.
Dynamics of charged fluids and 1/L perturbation expansions
Miloslav Znojil; Uwe Guenther
2007-04-19T23:59:59.000Z
Some features of the calculation of fluid dynamo systems in magnetohydrodynamics are studied. In the coupled set of the ordinary linear differential equations for the spherically symmetric $\\alpha^2-$dynamos, the problem represented by the presence of the mixed (Robin) boundary conditions is addressed and a new treatment for it is proposed. The perturbation formalism of large$-\\ell$ expansions is shown applicable and its main technical steps are outlined.
Cambridge, University of
to questions that either helps us construct appropriate mathematical models, and provide the data to validate of pollutants from our city streets? What governs the crystallisation of magma, or the progress of a pyroclastic of a suspended second phase? Is mix- ing sensitive to how we put the energy into the system? How do fluids
Huang, Zhiming
2012-07-16T23:59:59.000Z
The dissertation presents a CFD approach for 3D simulation of long risers. Long riser VIV simulation is at the frontier of the CFD research area due to its high demand on computational resources and techniques. It also has broad practical...
2.13 HEAT TRANSFER & FLUID FLOW IN MICROCHANNELS 2.13.7-1 Molecular dynamics methods in
Maruyama, Shigeo
2.13 HEAT TRANSFER & FLUID FLOW IN MICROCHANNELS 2.13.7-1 2.13.7 Molecular dynamics methods in microscale heat transfer Shigeo Maruyama A. Introduction In normal heat transfer and fluid flow calculations of molecules. This situation is approached in microscale heat transfer and fluid flow. Molecular level
Fluid Dynamic and Performance Behavior of Multiphase Progressive Cavity Pumps
Narayanan, Shankar Bhaskaran
2012-10-19T23:59:59.000Z
= Pressure of air inlet g1842g3031g3045g3036g3049g3032 = Power input to drive g1842g1858g1864g1873g1861g1856 = Power input to fluid g1842g1839g1857g1855?g1853g1866g1861g1855g1853g1864 g1838g1867g1871g1871g1857g1871 = Power lost due to mechanical losses.... ........................................................................................42 Figure 4.11 : Variable frequency drive. .............................................................................43 Figure 4.12 : Progressive cavity pump. .............................................................................44 Figure...
Geophysical Disaster Computational Fluid Dynamics Center Our scientific advances.
Â· Improve how Numerical Weather Prediction (NWP) models work. (numerics, dynamics, physics) Â· Use mountain-weather random errors by making many different NWP runs. (ensemble numerical prediction) Â· Reduce systematic outcomes. (probabilistic forecasting) Â· Predict weather and turbulence in the lower atmosphere where people
Dynamics of a confined dusty fluid in a sheared ion flow
Laishram, Modhuchandra; Sharma, Devendra; Kaw, Predhiman K. [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)
2014-07-15T23:59:59.000Z
Dynamics of an isothermally driven dust fluid is analyzed which is confined in an azimuthally symmetric cylindrical setup by an effective potential and is in equilibrium with an unconfined sheared flow of a streaming plasma. Cases are analyzed where the confining potential constitutes a barrier for the driven fluid, limiting its spatial extension and boundary velocity. The boundary effects entering the formulation are characterized by applying the appropriate boundary conditions and a range of solutions exhibiting single and multiple vortex are obtained. The equilibrium solutions considered in the cylindrical setup feature a transition from single to multiple vortex state of the driven flow. Effects of (i) the variation in dust viscosity, (ii) coupling between the driving and the driven fluid, and (iii) a friction determining the equilibrium dynamics of the driven system are characterized.
Chen, Qingyan "Yan"
1 Experimental Validation of a Computational Fluid Dynamics Model for IAQ applications in Ice Rink, USA, Fax: 617-432-4122, Abstract Many ice rink arenas have ice resurfacing equipment that uses fossil temperature distributions in ice rinks. The numerical results agree reasonably with the corresponding
AN INVESTIGATION OF THE FLUID DYNAMICS ASPECTS OF THIN LIQUID FILM PROTECTION
California at San Diego, University of
a conservative "design window" for film detachment. Initial observations of film flow around cy- lindricalAN INVESTIGATION OF THE FLUID DYNAMICS ASPECTS OF THIN LIQUID FILM PROTECTION SCHEMES FOR INERTIAL liquid film wall protection systems have been conducted in support of the ARIES-IFE study. Both
1 Two-Dimensional Computational Fluid Dynamics and Conduction Simulations of Heat Transfer Arasteh and Dragan Curcija ABSTRACT Accurately analyzing heat transfer in window frame cavities radiation heat-transfer effects.) We examine three representative complex cavity cross-section profiles
FLUID DYNAMIC ASPECTS OF THE POROUS WETTED WALL PROTECTION SCHEME FOR IFE REACTORS
FLUID DYNAMIC ASPECTS OF THE POROUS WETTED WALL PROTECTION SCHEME FOR IFE REACTORS S. Shin, F of Mechanical Engineering Georgia Institute of Technology Atlanta, GA 30332-0405 USA Number of Pages: 18 Number. Abdel-Khalik School of Mechanical Engineering Georgia Institute of Technology 771 Ferst Drive Atlanta
Fluid dynamics topics in bloodstain pattern analysis: Comparative review and research opportunities
Attinger, Daniel
Review Fluid dynamics topics in bloodstain pattern analysis: Comparative review and research a Department of Mechanical Engineering, Iowa State University of Science and Technology, Ames, IA 50011, USA b Engineering & Applied Science, Dalhousie University, Halifax, NS B3H 4R2, Canada d Department of Mechanical
THERMO FLUID DYNAMICS AND CHAMBER AEROSOL BEHAVIOR FOR THIN LIQUID WALL UNDER IFE
thermal and injection control. Experimental and numerical studies have been con- ducted to examine beam propagation and focusing requirements, as well as the target thermal integrity and injection the fluid dynamic aspects of thin-liquid- film protection systems with either radial injection through
On the Dynamics of Magnetic Fluids in Magnetic Resonance Padraig J. Cantillon-Murphy
in Magnetic Resonance Imaging by Padraig J. Cantillon-Murphy B.E., Electrical and Electronic EngineeringOn the Dynamics of Magnetic Fluids in Magnetic Resonance Imaging by Padraig J. Cantillon-Murphy Submitted to the Department of Electrical Engineering and Computer Science in partial fulfillment
Off-fault plasticity and earthquake rupture dynamics: 2. Effects of fluid saturation
Off-fault plasticity and earthquake rupture dynamics: 2. Effects of fluid saturation Robert C slip-weakening behavior is specified, and the off-fault material is described using an elastic-plastic poroelastoplastic materials with and without plastic dilation. During nondilatant undrained response near
Charles A. Stock Research Oceanographer, NOAA/Geophysical Fluid Dynamics Laboratory
Change Impacts on Living Marine Resources", 2012 Ocean Sciences Meeting, Salt Lake City 2012-13 MemberCharles A. Stock Research Oceanographer, NOAA/Geophysical Fluid Dynamics Laboratory Princeton-mail: Charles.Stock@noaa.gov Education 2005 Ph.D., Woods Hole Oceanographic Institution/MIT Joint Program Civil
Fluxion: An Innovative Fluid Dynamics Game on Multi-Touch Handheld Device
Boyer, Edmond
)). For example, players can place a heater to turn water into gas or place a freezer to turn it into ice. hal) (b) (c) Fig. 3. (a) A heater turns water into gas. (b) Water is turned into an ice cube so simulation on iPhone to create an innovative game experience. Using fluid dynamics and water tri
Computational Fluid Dynamics Evaluation of Good Combustion Performance in Waste Incinerators
Kim, Yong Jung
-furnace destruction of pollutants are stated as: good combustion is achieved when 2-second gas residence time at 850 C1 Computational Fluid Dynamics Evaluation of Good Combustion Performance in Waste Incinerators waste incinerators, good combustion practices(GCP or GOP) have been established. These operating (and
A next-generation modeling capability assesses wind turbine array fluid dynamics and aeroelastic of multi-megawatt turbines requires a new generation of modeling capability to assess individual turbine. Key Result The work is generating several models, including actuator line models of several wind
Tezduyar, Tayfun E.
Chapter 17 in Encyclopedia of Computational Mechanics, Volume 3: Fluids Finite Element Methods surfaces, two-fluid interfaces, fluidÂobject and fluidÂstructure in- teractions, and moving mechanical in Encyclopedia of Computational Mechanics, Volume 3: Fluids (eds. E. Stein, R. De Borst and T.J.R. Hughes), John
Applying one-dimensional fluid thermal elements into a 3D CLIC accelerating strucutre
Raatikainen, Riku; Österberg, Kenneth; Riddone, Germana; Samoshkin, Alexander; Gudkov, Dmitry
2010-01-01T23:59:59.000Z
A finite element modeling method to simplify the analysis of coupled thermal-structural model for the CLIC accelerating structure is presented. In addition, the results of thermal and structural analyses for the accelerating structure are presented. Instead of using a standard 3D computational fluid dynamics (CFD) method for solving problems involving fluid dynamics and heat transfer in 3D environment, one-dimensional fluid thermal elements are used. In one-dimensional flow, the governing equations of fluid dynamics are considerably simplified. Thus, it is expected that the computational time for more complex simulations becomes shorter. The method was first applied to several test models, which demonstrated the suitability of the one-dimensional flow modeling. The results show that one-dimensional fluid flow reduces the computation time considerably allowing the modeling for the future larger assemblies with sufficient accuracy.
Direct control of the small-scale energy balance in 2D fluid dynamics
Frank, Jason; Myerscough, Keith
2014-01-01T23:59:59.000Z
We explore the direct modification of the pseudo-spectral truncation of 2D, incompressible fluid dynamics to maintain a prescribed kinetic energy spectrum. The method provides a means of simulating fluid states with defined spectral properties, for the purpose of matching simulation statistics to given information, arising from observations, theoretical prediction or high fidelity simulation. In the scheme outlined here, Nos\\'e-Hoover thermostats, commonly used in molecular dynamics, are introduced as feedback controls applied to energy shells of the Fourier-discretized Navier-Stokes equations. As we demonstrate in numerical experiments, the dynamical properties (quantified using autocorrelation functions) are only modestly perturbed by our device, while ensemble dispersion is significantly enhanced in comparison with simulations of a corresponding truncation incorporating hyperviscosity.
Computational Methods for Analyzing Fluid Flow Dynamics from Digital Imagery
Luttman, A.
2012-03-30T23:59:59.000Z
The main goal (long term) of this work is to perform computational dynamics analysis and quantify uncertainty from vector fields computed directly from measured data. Global analysis based on observed spatiotemporal evolution is performed by objective function based on expected physics and informed scientific priors, variational optimization to compute vector fields from measured data, and transport analysis proceeding with observations and priors. A mathematical formulation for computing flow fields is set up for computing the minimizer for the problem. An application to oceanic flow based on sea surface temperature is presented.
Hazen, Terry
Proceedings Dynamics of Fluids in Fractured Rocks. LBNL-42718, Berkeley, CA February 1999 169 in monitoring wells near the injection point. #12;Proceedings Dynamics of Fluids in Fractured Rocks. LBNL-42718
PIV Uncertainty Methodologies for CFD Code Validation at the MIR Facility
Piyush Sabharwall; Richard Skifton; Carl Stoots; Eung Soo Kim; Thomas Conder
2013-12-01T23:59:59.000Z
Currently, computational fluid dynamics (CFD) is widely used in the nuclear thermal hydraulics field for design and safety analyses. To validate CFD codes, high quality multi dimensional flow field data are essential. The Matched Index of Refraction (MIR) Flow Facility at Idaho National Laboratory has a unique capability to contribute to the development of validated CFD codes through the use of Particle Image Velocimetry (PIV). The significance of the MIR facility is that it permits non intrusive velocity measurement techniques, such as PIV, through complex models without requiring probes and other instrumentation that disturb the flow. At the heart of any PIV calculation is the cross-correlation, which is used to estimate the displacement of particles in some small part of the image over the time span between two images. This image displacement is indicated by the location of the largest peak. In the MIR facility, uncertainty quantification is a challenging task due to the use of optical measurement techniques. Currently, this study is developing a reliable method to analyze uncertainty and sensitivity of the measured data and develop a computer code to automatically analyze the uncertainty/sensitivity of the measured data. The main objective of this study is to develop a well established uncertainty quantification method for the MIR Flow Facility, which consists of many complicated uncertainty factors. In this study, the uncertainty sources are resolved in depth by categorizing them into uncertainties from the MIR flow loop and PIV system (including particle motion, image distortion, and data processing). Then, each uncertainty source is mathematically modeled or adequately defined. Finally, this study will provide a method and procedure to quantify the experimental uncertainty in the MIR Flow Facility with sample test results.
Richard W. Johnson; Hugh M. McIlroy
2010-08-01T23:59:59.000Z
The U. S. Department of Energy (DOE) is supporting the development of a next generation nuclear plant (NGNP), which will be based on a very high temperature reactor (VHTR) design. The VHTR is a single-phase helium-cooled reactor wherein the helium will be heated initially to 750 °C and later to temperatures approaching 1000 °C. The high temperatures are desired to increase reactor efficiency and to provide a heat source for the manufacture of hydrogen and other applications. While computational fluid dynamics (CFD) has not been used in the past to design or license nuclear reactors in the U. S., it is expected that CFD will be used in the design and safety analysis of forthcoming designs. This is partly because of the maturity of CFD and partly because detailed information is desired of the flow and heat transfer inside the reactor to avoid hot spots and other conditions that might compromise reactor safety. Numerical computations of turbulent flow should be validated against experimental data for flow conditions that contain some or all of the physics expected in the thermal fluid machinery of interest. To this end, a scaled model of a narrow slice of the lower plenum of the prismatic VHTR was constructed and installed in the Idaho National Laboratory’s (INL) matched index of refraction (MIR) test facility and data were taken. The data were then studied and compared to CFD calculations to help determine their suitability for validation data. One of the main findings was that the inlet data, which were measured and controlled by calibrated mass flow rotameters and were also measured using detailed stereo particle image velocimetry (PIV) showed considerable discrepancies in mass flow rate between the two methods. The other finding was that a randomly unstable recirculation zone occurs in the flow. This instability has a very significant effect on the flow field in the vicinity of the inlet jets. Because its time scale is long and because it is apparently a random instability, it was deemed undesirable for a validation data set. It was predicted using CFD that by eliminating the first of the four jets, the recirculation zone could be stabilized. The present paper reports detailed results for the three-jet case with comparisons to the four-jet data inasmuch as three-jet data are still unavailable. Hence, the present simulations are true or blind predictions.
Hp-spectral Methods for Structural Mechanics and Fluid Dynamics Problems
Ranjan, Rakesh
2011-08-08T23:59:59.000Z
based finite element methods with the Penalty finite element method are presented for modelling porous media flow problems. Finally, we explore applications to some CFD problems namely, the flow past a cylinder and forward facing step....
Off-fault plasticity and earthquake rupture dynamics: 1. Dry materials or neglect of fluid pressure an explicit dynamic finite element procedure. A Mohr-Coulomb type elastic-plastic description describes-fault plasticity during dynamic rupture. Those include the angle with the fault of the maximum compressive
A transient study on the dynamic coupling of a fluid-tank system
Lui, Pui Chun
1980-01-01T23:59:59.000Z
A TRANSIENT STUDY ON THE DYNAMIC COUPLING OF A FLUID-TANK SYSTEM A Thesis by PUI CHUN LUI Approved as to style and content by: ( airman of Ccrmittee) (Head of Department) (Member) (Member) August 1980 ABSTBACT A Transient Study... liquid-tank system are of great concern. This dl annie coupling problem is studied analy- tically for a t?o-dimensional, rectangular, rigid tank with no baffles. The governing equations of the liquid motion are derived with reference to a moving...
Approved Module Information for ME4501, 2014/5 Module Title/Name: Computational Fluid Dynamics and
Neirotti, Juan Pablo
-requisites: Thermodynamics and Fluids (ME3011). Engineering Mathematics 2 (AM21EM). Co-requisites: None Specified ModuleApproved Module Information for ME4501, 2014/5 Module Title/Name: Computational Fluid Dynamics and Applications Module Code: ME4501 School: Engineering and Applied Science Module Type: Standard Module New
Gerhard Strydom; Su-Jong Yoon
2014-04-01T23:59:59.000Z
Computational Fluid Dynamics (CFD) evaluation of homogeneous and heterogeneous fuel models was performed as part of the Phase I calculations of the International Atomic Energy Agency (IAEA) Coordinate Research Program (CRP) on High Temperature Reactor (HTR) Uncertainties in Modeling (UAM). This study was focused on the nominal localized stand-alone fuel thermal response, as defined in Ex. I-3 and I-4 of the HTR UAM. The aim of the stand-alone thermal unit-cell simulation is to isolate the effect of material and boundary input uncertainties on a very simplified problem, before propagation of these uncertainties are performed in subsequent coupled neutronics/thermal fluids phases on the benchmark. In many of the previous studies for high temperature gas cooled reactors, the volume-averaged homogeneous mixture model of a single fuel compact has been applied. In the homogeneous model, the Tristructural Isotropic (TRISO) fuel particles in the fuel compact were not modeled directly and an effective thermal conductivity was employed for the thermo-physical properties of the fuel compact. On the contrary, in the heterogeneous model, the uranium carbide (UCO), inner and outer pyrolytic carbon (IPyC/OPyC) and silicon carbide (SiC) layers of the TRISO fuel particles are explicitly modeled. The fuel compact is modeled as a heterogeneous mixture of TRISO fuel kernels embedded in H-451 matrix graphite. In this study, a steady-state and transient CFD simulations were performed with both homogeneous and heterogeneous models to compare the thermal characteristics. The nominal values of the input parameters are used for this CFD analysis. In a future study, the effects of input uncertainties in the material properties and boundary parameters will be investigated and reported.
Some CFD Books Classics and General Purpose
Slinn, Donald
., M. Y. Hussaini, A. Quarteroni, T. A. Zang, Spectral Methods in Fluid Dynamics, 1987, Springer Verlag, CRC Press, Boca Raton, ISBN 0-8493-9410-4. Shyy, W., H. S. Udaykumar, M. M. Rao, and R. W. Smith
Bonneville Powerhouse 2 Fish Guidance Efficiency Studies: CFD Model of the Forebay
Rakowski, Cynthia L.; Serkowski, John A.; Richmond, Marshall C.
2012-07-01T23:59:59.000Z
In ongoing work, U.S. Army Corps of Engineers, Portland District (CENWP) is seeking to better understand and improve the conditions within the Bonneville Powerhouse 2 (B2) turbine intakes to improve survival of downstream migrant salmonid smolt. In this study, the existing B2 forebay computational fluid dynamics (CFD) model was modified to include a more detailed representation of all B2 turbine intakes. The modified model was validated to existing field-measured forebay ADCP velocities. The initial CFD model scenarios tested a single project operation and the impact of adding the Behavior Guidance System (BGS) or Corner Collector. These structures had impacts on forebay flows. Most notable was that the addition of the BGS and Corner Collector reduced the lateral extent of the recirculation areas on the Washington shore and Cascade Island and reduced the flow velocity parallel to the powerhouse in front of Units 11 and 12. For these same cases, at the turbine intakes across the powerhouse, there was very little difference in the flow volume into the gatewell for the clean forebay, and the forebay with the BGS in place and/or the Corner Collector operating. The largest differences were at Units 11 to 13. The CFD model cases testing the impact of the gatewell slot fillers showed no impact to the forebay flows, but large differences within the gatewells. With the slot fillers, the flow above the standard traveling screen and into the gatewell increased (about 100 cfs at each turbine intake) and the gap flow decreased across the powerhouse for all cases. The increased flow up the gatewell was further enhanced with only half the units operating. The flow into the gatewell slot was increased about 35 cfs for each bay of each intake across the powerhouse; this change was uniform across the powerhouse. The flows in the gatewell of Unit 12, the most impacted unit for the scenarios, was evaluated. In front of the vertical barrier screen, the CFD model with slot fillers showed reduced the maximum velocities (in spite of the increased the flow into the gatewell), and decreased the area of recirculation. The area near the VBS exceeding the normal velocity criteria of 1 ft/s was reduced and the flows were more balanced.
Faybishenko, B. (ed.)
1999-02-01T23:59:59.000Z
This publication contains extended abstracts of papers presented at the International Symposium ''Dynamics of Fluids in Fractured Rocks: Concepts and Recent Advances'' held at Ernest Orlando Lawrence Berkeley National Laboratory on February 10-12, 1999. This Symposium is organized in Honor of the 80th Birthday of Paul A. Witherspoon, who initiated some of the early investigations on flow and transport in fractured rocks at the University of California, Berkeley, and at Lawrence Berkeley National Laboratory. He is a key figure in the development of basic concepts, modeling, and field measurements of fluid flow and contaminant transport in fractured rock systems. The technical problems of assessing fluid flow, radionuclide transport, site characterization, modeling, and performance assessment in fractured rocks remain the most challenging aspects of subsurface flow and transport investigations. An understanding of these important aspects of hydrogeology is needed to assess disposal of nu clear wastes, development of geothermal resources, production of oil and gas resources, and remediation of contaminated sites. These Proceedings of more than 100 papers from 12 countries discuss recent scientific and practical developments and the status of our understanding of fluid flow and radionuclide transport in fractured rocks. The main topics of the papers are: Theoretical studies of fluid flow in fractured rocks; Multi-phase flow and reactive chemical transport in fractured rocks; Fracture/matrix interactions; Hydrogeological and transport testing; Fracture flow models; Vadose zone studies; Isotopic studies of flow in fractured systems; Fractures in geothermal systems; Remediation and colloid transport in fractured systems; and Nuclear waste disposal in fractured rocks.
CFD Validation of Gas Injection in Flowing Mercury over Vertical Smooth and Grooved Wall
Abdou, Ashraf A [ORNL; Wendel, Mark W [ORNL; Felde, David K [ORNL; Riemer, Bernie [ORNL
2009-01-01T23:59:59.000Z
The Spallation Neutron Source (SNS) is an accelerator-based neutron source at Oak Ridge National Laboratory (ORNL).The nuclear spallation reaction occurs when a proton beam hits liquid mercury. This interaction causes thermal expansion of the liquid mercury which produces high pressure waves. When these pressure waves hit the target vessel wall, cavitation can occur and erode the wall. Research and development efforts at SNS include creation of a vertical protective gas layer between the flowing liquid mercury and target vessel wall to mitigate the cavitation damage erosion and extend the life time of the target. Since mercury is opaque, computational fluid dynamics (CFD) can be used as a diagnostic tool to see inside the liquid mercury and guide the experimental efforts. In this study, CFD simulations of three dimensional, unsteady, turbulent, two-phase flow of helium gas injection in flowing liquid mercury over smooth, vertically grooved and horizontally grooved walls are carried out with the commercially available CFD code Fluent-12 from ANSYS. The Volume of Fluid (VOF) model is used to track the helium-mercury interface. V-shaped vertical and horizontal grooves with 0.5 mm pitch and about 0.7 mm depth were machined in the transparent wall of acrylic test sections. Flow visualization data of helium gas coverage through transparent test sections is obtained with a high-speed camera at the ORNL target test facility (TTF). The helium gas mass flow rate is 8 mg/min and introduced through a 0.5 mm diameter port. The local mercury velocity is 0.9 m/s. In this paper, the helium gas flow rate and the local mercury velocity are kept constant for the three cases. Time integration of predicted helium gas volume fraction over time is done to evaluate the gas coverage and calculate the average thickness of the helium gas layer. The predicted time-integrated gas coverage over vertically grooved and horizontally grooved test sections is better than over a smooth wall. The simulations show that the helium gas is trapped inside the grooves. The predicted time-averaged gas coverage is in good qualitative agreement with the measured gas coverage.
Sructure and dynamics of fluids in micropous and mesoporous earth and engineered materials
Cole, David R [ORNL; Mamontov, Eugene [ORNL; Rother, Gernot [ORNL
2009-01-01T23:59:59.000Z
The behavior of liquids in confined geometries (pores, fractures) typically differs, due to the effects of large internal surfaces and geometri-cal confinement, from their bulk behavior in many ways. Phase transitions (i.e., freezing and capillary condensation), sorption and wetting, and dy-namical properties, including diffusion and relaxation, may be modified, with the strongest changes observed for pores ranging in size from <2 nm to 50 nm the micro- and mesoporous regimes. Important factors influ-encing the structure and dynamics of confined liquids include the average pore size and pore size distribution, the degree of pore interconnection, and the character of the liquid-surface interaction. While confinement of liq-uids in hydrophobic matrices, such as carbon nanotubes, or near the sur-faces of mixed character, such as many proteins, has also been an area of rapidly growing interest, the confining matrices of interest to earth and ma-terials sciences usually contain oxide structural units and thus are hydro-philic. The pore size distribution and the degree of porosity and inter-connection vary greatly amongst porous matrices. Vycor, xerogels, aerogels, and rocks possess irregular porous structures, whereas mesopor-ous silicas (e.g., SBA-15, MCM-41, MCM-48), zeolites, and layered sys-tems, for instance clays, have high degrees of internal order. The pore type and size may be tailored by means of adjusting the synthesis regimen. In clays, the interlayer distance may depend on the level of hydration. Al-though studied less frequently, matrices such as artificial opals and chry-sotile asbestos represent other interesting examples of ordered porous structures. The properties of neutrons make them an ideal probe for com-paring the properties of bulk fluids with those in confined geometries. In this chapter, we provide a brief review of research performed on liquids confined in materials of interest to the earth and material sciences (silicas, aluminas, zeolites, clays, rocks, etc.), emphasizing those neutron scattering techniques which assess both structural modification and dynamical behav-ior. Quantitative understanding of the complex solid-fluid interactions under different thermodynamic situations will impact both the design of bet-ter substrates for technological applications (e.g., chromatography, fluid capture, storage and release, and heterogeneous catalysis) as well as our fundamental understanding of processes encountered in the environment (i.e., fluid and waste mitigation, carbon sequestration, etc.).
Prerna Sharma; P. Aswathi; Anit Sane; Shankar Ghosh; S. Bhattacharya
2011-03-22T23:59:59.000Z
Two-fluid interfaces in porous media, an example of driven disordered systems, were studied by a real time three-dimensional imaging technique with pore scale resolution for a less viscous fluid displacing a more viscous one. With increasing flow rate the interface transforms from flat to fingers and thence to droplets for both drainage and imbibition. The results compare and contrast the effects of randomness, both physical (geometry of the pore space) and chemical (wettability of the fluids), on the dynamical instability and identify the origin of the pore-scale processes that govern them.
D. M. McEligot; K.G. Condie; G. E. Mc Creery; H. M. Mc Ilroy
2005-09-01T23:59:59.000Z
The objective of the present report is to document the design of our first experiment to measure generic flow phenomena expected to occur in the lower plenum of a typical prismatic VHTR (Very High Temperature Reactor) concept. In the process, fabrication sketches are provided for the use of CFD (computational fluid dynamics) analysts wishing to employ the data for assessment of their proposed codes. The general approach of the project is to develop new benchmark experiments for assessment in parallel with CFD and coupled CFD/systems code calculations for the same geometry. One aspect of the complex flow in a prismatic VHTR is being addressed: flow and thermal mixing in the lower plenum ("hot streaking" issue). Current prismatic VHTR concepts were examined to identify their proposed flow conditions and geometries over the range from normal operation to decay heat removal in a pressurized cooldown. Approximate analyses were applied to determine key non-dimensional parameters and their magnitudes over this operating range. The flow in the lower plenum can locally be considered to be a situation of multiple jets into a confined crossflow -- with obstructions. Flow is expected to be turbulent with momentum-dominated turbulent jets entering; buoyancy influences are estimated to be negligible in normal full power operation. Experiments are needed for the combined features of the lower plenum flows. Missing from the typical jet experiments available are interactions with nearby circular posts and with vertical posts in the vicinity of vertical walls - with near stagnant surroundings at one extreme and significant crossflow at the other.
Transient Temperature Modeling For Wellbore Fluid Under Static and Dynamic Conditions
Ali, Muhammad
2014-04-22T23:59:59.000Z
for geothermal wells and prediction of injection fluid temperatures. In this thesis, development and usage of three models for transient fluid temperature are presented. Two models predict transient temperature of flowing fluid under separate flow configurations...
Thermo-fluid Dynamics of Flash Atomizing Sprays and Single Droplet Impacts
Vu, Henry
2010-01-01T23:59:59.000Z
Journal Series B-Fluids and Thermal Engineering, 1994. 37(Journal Series B-Fluids and Thermal Engineering, 1994. 37 (Journal Series B-Fluids and Thermal Engineering, 1994. 37(
Mottram, Nigel
, Dr Derek Bennet, Expro Group 14:30 Leveraging the power of ARCHIE-WeSt for CFD with OpenFOAM, Dr Tom
Inverse patchy colloids with small patches: fluid structure and dynamical slowing down
Silvano Ferrari; Emanuela Bianchi; Yura V. Kalyuzhnyi; Gerhard Kahl
2014-12-11T23:59:59.000Z
Inverse Patchy Colloids (IPCs) differ from conventional patchy particles because their patches repel (rather than attract) each other and attract (rather than repel) the part of the colloidal surface that is free of patches. These particular features occur, .e.g., in heterogeneously charged colloidal systems. Here we consider overall neutral IPCs carrying two, relatively small, polar patches. Previous studies of the same model under planar confinement have evidenced the formation of branched, disordered aggregates composed of ring-like structures. We investigate here the bulk behavior of the system via molecular dynamics simulations, focusing on both the structure and the dynamics of the fluid phase in a wide region of the phase diagram. Additionally, the simulation results for the static observables are compared to the Associative Percus Yevick solution of an integral equation approach based on the multi-density Ornstein-Zernike theory. A good agreement between theoretical and numerical quantities is observed even in the region of the phase diagram where the slowing down of the dynamics occurs.
Sandia National Laboratories environmental fluid dynamics code : sediment transport user manual.
Grace, Matthew D.; Thanh, Phi Hung X.; James, Scott Carlton
2008-09-01T23:59:59.000Z
This document describes the sediment transport subroutines and input files for the Sandia National Laboratories Environmental Fluid Dynamics Code (SNL-EFDC). Detailed descriptions of the input files containing data from Sediment Erosion at Depth flume (SEDflume) measurements are provided along with the description of the source code implementing sediment transport. Both the theoretical description of sediment transport employed in SNL-EFDC and the source code are described. This user manual is meant to be used in conjunction with the EFDC manual (Hamrick 1996) because there will be no reference to the hydrodynamics in EFDC. Through this document, the authors aim to provide the necessary information for new users who wish to implement sediment transport in EFDC and obtain a clear understanding of the source code.
Oelfke, John Barry; Torczynski, John Robert; O'Hern, Timothy John; Tortora, Paul Richard; Bhusarapu, Satish (; ); Trujillo, Steven Mathew
2006-08-01T23:59:59.000Z
An experimental program was conducted to study the multiphase gas-solid flow in a pilot-scale circulating fluidized bed (CFB). This report describes the CFB experimental facility assembled for this program, the diagnostics developed and/or applied to make measurements in the riser section of the CFB, and the data acquired for several different flow conditions. Primary data acquired included pressures around the flow loop and solids loadings at selected locations in the riser. Tomographic techniques using gamma radiation and electrical capacitance were used to determine radial profiles of solids volume fraction in the riser, and axial profiles of the integrated solids volume fraction were produced. Computer Aided Radioactive Particle Tracking was used to measure solids velocities, fluxes, and residence time distributions. In addition, a series of computational fluid dynamics simulations was performed using the commercial code Arenaflow{trademark}.
A New CFD Model for understanding and Managing Diesel Particulate...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
CFD Model for understanding and Managing Diesel Particulate Filter Regeneration A New CFD Model for understanding and Managing Diesel Particulate Filter Regeneration...
Eulerian CFD Models to Predict Thermophoretic Deposition of Soot...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Eulerian CFD Models to Predict Thermophoretic Deposition of Soot Particles in EGR Coolers Eulerian CFD Models to Predict Thermophoretic Deposition of Soot Particles in EGR Coolers...
Gable, Carl W.
From: Numerical Grid Generation in Computational Fluid Dynamics and Related Fields, ed. B. K. Soni. Press, 1996. 1 From: Numerical Grid Generation in Computational Fluid Dynamics and Related Fields, ed. B State Univ. Press, 1996. Geological Applications of Automatic Grid Generation Tools for Finite Elements
Under consideration for publication in J. Fluid Mech. 1 Tear Film Dynamics on an Eye-shaped
Bacuta, Constantin
Under consideration for publication in J. Fluid Mech. 1 Tear Film Dynamics on an Eye-shaped Domain of vision and in the health of the eye; when functioning properly, it maintains a critical balance between or deficiency of tear film is recognized to be dry eye syndrome (Lemp (2007)); symptoms of dry eye include
Chen, Qingyan "Yan"
Fast and Informative Flow Simulations in a Building by Using Fast Fluid Dynamics Model on Graphics solve Navier-Stokes equations and other transportation equations for energy and species at a speed of 50 it in parallel on a Graphics Processing Unit (GPU). This study validated the FFD on the GPU by simulating
Notes 10. A thermohydrodynamic bulk-flow model for fluid film bearings
San Andres, Luis
2009-01-01T23:59:59.000Z
The complete set of bulk-flow equations for the analysis of turbulent flow fluid film bearings. Importance of thermal effects in process fluid applications. A CFD method for solution of the bulk-flow equations....
3D CFD Model of High Temperature H2O/CO2 Co-electrolysis
Grant Hawkes; James O'Brien; Carl Stoots; Stephen Herring; Joe Hartvigsen
2007-06-01T23:59:59.000Z
3D CFD Model of High Temperature H2O/CO2 Co-Electrolysis Grant Hawkes1, James O’Brien1, Carl Stoots1, Stephen Herring1 Joe Hartvigsen2 1 Idaho National Laboratory, Idaho Falls, Idaho, grant.hawkes@inl.gov 2 Ceramatec Inc, Salt Lake City, Utah INTRODUCTION A three-dimensional computational fluid dynamics (CFD) model has been created to model high temperature co-electrolysis of steam and carbon dioxide in a planar solid oxide electrolyzer (SOE) using solid oxide fuel cell technology. A research program is under way at the Idaho National Laboratory (INL) to simultaneously address the research and scale-up issues associated with the implementation of planar solid-oxide electrolysis cell technology for syn-gas production from CO2 and steam. Various runs have been performed under different run conditions to help assess the performance of the SOE. This paper presents CFD results of this model compared with experimental results. The Idaho National Laboratory (INL), in conjunction with Ceramatec Inc. (Salt Lake City, USA) has been researching for several years the use of solid-oxide fuel cell technology to electrolyze steam for large-scale nuclear-powered hydrogen production. Now, an experimental research project is underway at the INL to produce syngas by simultaneously electrolyzing at high-temperature steam and carbon dioxide (CO2) using solid oxide fuel cell technology. A strong interest exists in the large-scale production of syn-gas from CO2 and steam to be reformed into a usable transportation fuel. If biomass is used as the carbon source, the overall process is climate neutral. Consequently, there is a high level of interest in production of syn-gas from CO2 and steam electrolysis. With the price of oil currently around $60 / barrel, synthetically-derived hydrocarbon fuels (synfuels) have become economical. Synfuels are typically produced from syngas – hydrogen (H2) and carbon monoxide (CO) -- using the Fischer-Tropsch process, discovered by Germany before World War II. High-temperature nuclear reactors have the potential for substantially increasing the efficiency of syn-gas production from CO2 and water, with no consumption of fossil fuels, and no production of greenhouse gases. Thermal CO2-splitting and water splitting for syn-gas production can be accomplished via high-temperature electrolysis, using high-temperature nuclear process heat and electricity. A high-temperature advanced nuclear reactor coupled with a high-efficiency high-temperature electrolyzer could achieve a competitive thermal-to-syn-gas conversion efficiency of 45 to 55%.
Donna Post Guillen; Daniel S. Wendt
2007-11-01T23:59:59.000Z
The purpose of this paper is to document the review of several open-literature sources of both experimental capabilities and published hydrodynamic data to aid in the validation of a Computational Fluid Dynamics (CFD) based model of a slurry bubble column (SBC). The review included searching the Web of Science, ISI Proceedings, and Inspec databases, internet searches as well as other open literature sources. The goal of this study was to identify available experimental facilities and relevant data. Integral (i.e., pertaining to the SBC system), as well as fundamental (i.e., separate effects are considered), data are included in the scope of this effort. The fundamental data is needed to validate the individual mechanistic models or closure laws used in a Computational Multiphase Fluid Dynamics (CMFD) simulation of a SBC. The fundamental data is generally focused on simple geometries (i.e., flow between parallel plates or cylindrical pipes) or custom-designed tests to focus on selected interfacial phenomena. Integral data covers the operation of a SBC as a system with coupled effects. This work highlights selected experimental capabilities and data for the purpose of SBC model validation, and is not meant to be an exhaustive summary.
Donna Post Guillen; Daniel S. Wendt; Steven P. Antal; Michael Z. Podowski
2007-11-01T23:59:59.000Z
The purpose of this paper is to document the review of several open-literature sources of both experimental capabilities and published hydrodynamic data to aid in the validation of a Computational Fluid Dynamics (CFD) based model of a slurry bubble column (SBC). The review included searching the Web of Science, ISI Proceedings, and Inspec databases, internet searches as well as other open literature sources. The goal of this study was to identify available experimental facilities and relevant data. Integral (i.e., pertaining to the SBC system), as well as fundamental (i.e., separate effects are considered), data are included in the scope of this effort. The fundamental data is needed to validate the individual mechanistic models or closure laws used in a Computational Multiphase Fluid Dynamics (CMFD) simulation of a SBC. The fundamental data is generally focused on simple geometries (i.e., flow between parallel plates or cylindrical pipes) or custom-designed tests to focus on selected interfacial phenomena. Integral data covers the operation of a SBC as a system with coupled effects. This work highlights selected experimental capabilities and data for the purpose of SBC model validation, and is not meant to be an exhaustive summary.
B. D. Nichols; C. Müller; G. A. Necker; J. R. Travis; J. W. Spore; K. L. Lam; P. Royl; T. L. Wilson
1998-10-01T23:59:59.000Z
Los Alamos National Laboratory (LANL) and Forschungszentrum Karlsruhe (FzK) are developing GASFLOW, a three-dimensional (3D) fluid dynamics field code as a best-estimate tool to characterize local phenomena within a flow field. Examples of 3D phenomena include circulation patterns; flow stratification; hydrogen distribution mixing and stratification; combustion and flame propagation; effects of noncondensable gas distribution on local condensation and evaporation; and aerosol entrainment, transport, and deposition. An analysis with GASFLOW will result in a prediction of the gas composition and discrete particle distribution in space and time throughout the facility and the resulting pressure and temperature loadings on the walls and internal structures with or without combustion. A major application of GASFLOW is for predicting the transport, mixing, and combustion of hydrogen and other gases in nuclear reactor containment and other facilities. It has been applied to situations involving transporting and distributing combustible gas mixtures. It has been used to study gas dynamic behavior in low-speed, buoyancy-driven flows, as well as sonic flows or diffusion dominated flows; and during chemically reacting flows, including deflagrations. The effects of controlling such mixtures by safety systems can be analyzed. The code version described in this manual is designated GASFLOW 2.1, which combines previous versions of the United States Nuclear Regulatory Commission code HMS (for Hydrogen Mixing Studies) and the Department of Energy and FzK versions of GASFLOW. The code was written in standard Fortran 90. This manual comprises three volumes. Volume I describes the governing physical equations and computational model. Volume II describes how to use the code to set up a model geometry, specify gas species and material properties, define initial and boundary conditions, and specify different outputs, especially graphical displays. Sample problems are included. Volume III contains some of the assessments performed by LANL and FzK.
C. Müller; E. D. Hughes; G. F. Niederauer; H. Wilkening; J. R. Travis; J. W. Spore; P. Royl; W. Baumann
1998-10-01T23:59:59.000Z
Los Alamos National Laboratory (LANL) and Forschungszentrum Karlsruhe (FzK) are developing GASFLOW, a three-dimensional (3D) fluid dynamics field code as a best- estimate tool to characterize local phenomena within a flow field. Examples of 3D phenomena include circulation patterns; flow stratification; hydrogen distribution mixing and stratification; combustion and flame propagation; effects of noncondensable gas distribution on local condensation and evaporation; and aerosol entrainment, transport, and deposition. An analysis with GASFLOW will result in a prediction of the gas composition and discrete particle distribution in space and time throughout the facility and the resulting pressure and temperature loadings on the walls and internal structures with or without combustion. A major application of GASFLOW is for predicting the transport, mixing, and combustion of hydrogen and other gases in nuclear reactor containment and other facilities. It has been applied to situations involving transporting and distributing combustible gas mixtures. It has been used to study gas dynamic behavior in low-speed, buoyancy-driven flows, as well as sonic flows or diffusion dominated flows; and during chemically reacting flows, including deflagrations. The effects of controlling such mixtures by safety systems can be analyzed. The code version described in this manual is designated GASFLOW 2.1, which combines previous versions of the United States Nuclear Regulatory Commission code HMS (for Hydrogen Mixing Studies) and the Department of Energy and FzK versions of GASFLOW. The code was written in standard Fortran 90. This manual comprises three volumes. Volume I describes the governing physical equations and computational model. Volume II describes how to use the code to set up a model geometry, specify gas species and material properties, define initial and boundary conditions, and specify different outputs, especially graphical displays. Sample problems are included. Volume III contains some of the assessments performed by LANL and FzK
Wind Turbine Modeling for Computational Fluid Dynamics: December 2010 - December 2012
Tossas, L. A. M.; Leonardi, S.
2013-07-01T23:59:59.000Z
With the shortage of fossil fuel and the increasing environmental awareness, wind energy is becoming more and more important. As the market for wind energy grows, wind turbines and wind farms are becoming larger. Current utility-scale turbines extend a significant distance into the atmospheric boundary layer. Therefore, the interaction between the atmospheric boundary layer and the turbines and their wakes needs to be better understood. The turbulent wakes of upstream turbines affect the flow field of the turbines behind them, decreasing power production and increasing mechanical loading. With a better understanding of this type of flow, wind farm developers could plan better-performing, less maintenance-intensive wind farms. Simulating this flow using computational fluid dynamics is one important way to gain a better understanding of wind farm flows. In this study, we compare the performance of actuator disc and actuator line models in producing wind turbine wakes and the wake-turbine interaction between multiple turbines. We also examine parameters that affect the performance of these models, such as grid resolution, the use of a tip-loss correction, and the way in which the turbine force is projected onto the flow field.
CFD calculations of S809 aerodynamic characteristics
Wolfe, W.P. [Sandia National Labs., Albuquerque, NM (United States); Ochs, S.S. [Iowa State Univ., Ames, IA (United States)
1997-01-01T23:59:59.000Z
Steady-state, two-dimensional CFD calculations were made for the S809 laminar-flow, wind-turbine airfoil using the commercial code CFD-ACE. Comparisons of the computed pressure and aerodynamic coefficients were made with wind tunnel data from the Delft University 1.8 m x 1.25 m low-turbulence wind tunnel. This work highlights two areas in CFD that require further investigation and development in order to enable accurate numerical simulations of flow about current generation wind-turbine airfoils: transition prediction and turbulence modeling. The results show that the laminar-to-turbulent transition point must be modeled correctly to get accurate simulations for attached flow. Calculations also show that the standard turbulence model used in most commercial CFD codes, the k-{epsilon} model, is not appropriate at angles of attack with flow separation.
Multiscale CFD simulations of entrained flow gasification
Kumar, Mayank, Ph. D. Massachusetts Institute of Technology
2011-01-01T23:59:59.000Z
The design of entrained flow gasifiers and their operation has largely been an experience based enterprise. Most, if not all, industrial scale gasifiers were designed before it was practical to apply CFD models. Moreover, ...
Pre-test CFD Calculations for a Bypass Flow Standard Problem
Rich Johnson
2011-11-01T23:59:59.000Z
The bypass flow in a prismatic high temperature gas-cooled reactor (HTGR) is the flow that occurs between adjacent graphite blocks. Gaps exist between blocks due to variances in their manufacture and installation and because of the expansion and shrinkage of the blocks from heating and irradiation. Although the temperature of fuel compacts and graphite is sensitive to the presence of bypass flow, there is great uncertainty in the level and effects of the bypass flow. The Next Generation Nuclear Plant (NGNP) program at the Idaho National Laboratory has undertaken to produce experimental data of isothermal bypass flow between three adjacent graphite blocks. These data are intended to provide validation for computational fluid dynamic (CFD) analyses of the bypass flow. Such validation data sets are called Standard Problems in the nuclear safety analysis field. Details of the experimental apparatus as well as several pre-test calculations of the bypass flow are provided. Pre-test calculations are useful in examining the nature of the flow and to see if there are any problems associated with the flow and its measurement. The apparatus is designed to be able to provide three different gap widths in the vertical direction (the direction of the normal coolant flow) and two gap widths in the horizontal direction. It is expected that the vertical bypass flow will range from laminar to transitional to turbulent flow for the different gap widths that will be available.
Development of CFD models to support LEU Conversion of ORNL s High Flux Isotope Reactor
Khane, Vaibhav B [ORNL] [ORNL; Jain, Prashant K [ORNL] [ORNL; Freels, James D [ORNL] [ORNL
2012-01-01T23:59:59.000Z
The US Department of Energy s National Nuclear Security Administration (NNSA) is participating in the Global Threat Reduction Initiative to reduce and protect vulnerable nuclear and radiological materials located at civilian sites worldwide. As an integral part of one of NNSA s subprograms, Reduced Enrichment for Research and Test Reactors, HFIR is being converted from the present HEU core to a low enriched uranium (LEU) core with less than 20% of U-235 by weight. Because of HFIR s importance for condensed matter research in the United States, its conversion to a high-density, U-Mo-based, LEU fuel should not significantly impact its existing performance. Furthermore, cost and availability considerations suggest making only minimal changes to the overall HFIR facility. Therefore, the goal of this conversion program is only to substitute LEU for the fuel type in the existing fuel plate design, retaining the same number of fuel plates, with the same physical dimensions, as in the current HFIR HEU core. Because LEU-specific testing and experiments will be limited, COMSOL Multiphysics was chosen to provide the needed simulation capability to validate against the HEU design data and previous calculations, and predict the performance of the proposed LEU fuel for design and safety analyses. To achieve it, advanced COMSOL-based multiphysics simulations, including computational fluid dynamics (CFD), are being developed to capture the turbulent flows and associated heat transfer in fine detail and to improve predictive accuracy [2].
Payne, J.L.; Hassan, B.
1998-09-01T23:59:59.000Z
Massively parallel computers have enabled the analyst to solve complicated flow fields (turbulent, chemically reacting) that were previously intractable. Calculations are presented using a massively parallel CFD code called SACCARA (Sandia Advanced Code for Compressible Aerothermodynamics Research and Analysis) currently under development at Sandia National Laboratories as part of the Department of Energy (DOE) Accelerated Strategic Computing Initiative (ASCI). Computations were made on a generic reentry vehicle in a hypersonic flowfield utilizing three different distributed parallel computers to assess the parallel efficiency of the code with increasing numbers of processors. The parallel efficiencies for the SACCARA code will be presented for cases using 1, 150, 100 and 500 processors. Computations were also made on a subsonic/transonic vehicle using both 236 and 521 processors on a grid containing approximately 14.7 million grid points. Ongoing and future plans to implement a parallel overset grid capability and couple SACCARA with other mechanics codes in a massively parallel environment are discussed.
Gable, Carl W.
From: Numerical Grid Generation in Computational Fluid Dynamics and Related Fields, ed. B. K. Soni. Press, 1996. 3-Dimensional Wells and Tunnels for Finite Element Grids 1 3-Dimensional Wells and Tunnels for Finite Element Grids Terry A. Cherry1 Carl W. Gable1 Harold Trease2 ABSTRACT Modeling fluid, vapor
Numerical schemes for dynamically orthogonal equations of stochastic fluid and ocean flows
Ueckermann, M.P., E-mail: mpuecker@mit.edu [Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Mass. Avenue, Cambridge, MA 02139 (United States); Lermusiaux, P.F.J., E-mail: pierrel@mit.edu [Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Mass. Avenue, Cambridge, MA 02139 (United States)] [Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Mass. Avenue, Cambridge, MA 02139 (United States); Sapsis, T.P., E-mail: sapsis@mit.edu [Department of Mechanical Engineering, Massachusetts Institute of Technology, 77 Mass. Avenue, Cambridge, MA 02139 (United States)
2013-01-15T23:59:59.000Z
The quantification of uncertainties is critical when systems are nonlinear and have uncertain terms in their governing equations or are constrained by limited knowledge of initial and boundary conditions. Such situations are common in multiscale, intermittent and non-homogeneous fluid and ocean flows. The dynamically orthogonal (DO) field equations provide an adaptive methodology to predict the probability density functions of such flows. The present work derives efficient computational schemes for the DO methodology applied to unsteady stochastic Navier-Stokes and Boussinesq equations, and illustrates and studies the numerical aspects of these schemes. Semi-implicit projection methods are developed for the mean and for the DO modes, and time-marching schemes of first to fourth order are used for the stochastic coefficients. Conservative second-order finite-volumes are employed in physical space with new advection schemes based on total variation diminishing methods. Other results include: (i) the definition of pseudo-stochastic pressures to obtain a number of pressure equations that is linear in the subspace size instead of quadratic; (ii) symmetric advection schemes for the stochastic velocities; (iii) the use of generalized inversion to deal with singular subspace covariances or deterministic modes; and (iv) schemes to maintain orthonormal modes at the numerical level. To verify our implementation and study the properties of our schemes and their variations, a set of stochastic flow benchmarks are defined including asymmetric Dirac and symmetric lock-exchange flows, lid-driven cavity flows, and flows past objects in a confined channel. Different Reynolds number and Grashof number regimes are employed to illustrate robustness. Optimal convergence under both time and space refinements is shown as well as the convergence of the probability density functions with the number of stochastic realizations.
Collapse dynamics and runout of dense granular materials in a fluid V. Topina,b
Paris-Sud XI, UniversitÃ© de
is another example of the in- tricate grain/fluid mixing process in extreme conditions, which remains a real and enhance the flow by lubrication during spread. Hence, the runout distance in a fluid may be below or equal- port of a powder or a collection of aggregates in a liquid which plays the role of lubricant or binder
Development of a Prototype Lattice Boltzmann Code for CFD of Fusion Systems.
Pattison, Martin J; Premnath, Kannan N; Banerjee, Sanjoy; Dwivedi, Vinay
2007-02-26T23:59:59.000Z
Designs of proposed fusion reactors, such as the ITER project, typically involve the use of liquid metals as coolants in components such as heat exchangers, which are generally subjected to strong magnetic fields. These fields induce electric currents in the fluids, resulting in magnetohydrodynamic (MHD) forces which have important effects on the flow. The objective of this SBIR project was to develop computational techniques based on recently developed lattice Boltzmann techniques for the simulation of these MHD flows and implement them in a computational fluid dynamics (CFD) code for the study of fluid flow systems encountered in fusion engineering. The code developed during this project, solves the lattice Boltzmann equation, which is a kinetic equation whose behaviour represents fluid motion. This is in contrast to most CFD codes which are based on finite difference/finite volume based solvers. The lattice Boltzmann method (LBM) is a relatively new approach which has a number of advantages compared with more conventional methods such as the SIMPLE or projection method algorithms that involve direct solution of the Navier-Stokes equations. These are that the LBM is very well suited to parallel processing, with almost linear scaling even for very large numbers of processors. Unlike other methods, the LBM does not require solution of a Poisson pressure equation leading to a relatively fast execution time. A particularly attractive property of the LBM is that it can handle flows in complex geometries very easily. It can use simple rectangular grids throughout the computational domain -- generation of a body-fitted grid is not required. A recent advance in the LBM is the introduction of the multiple relaxation time (MRT) model; the implementation of this model greatly enhanced the numerical stability when used in lieu of the single relaxation time model, with only a small increase in computer time. Parallel processing was implemented using MPI and demonstrated the ability of the LBM to scale almost linearly. The equation for magnetic induction was also solved using a lattice Boltzmann method. This approach has the advantage that it fits in well to the framework used for the hydrodynamic equations, but more importantly that it preserves the ability of the code to run efficiently on parallel architectures. Since the LBM is a relatively recent model, a number of new developments were needed to solve the magnetic induction equation for practical problems. Existing methods were only suitable for cases where the fluid viscosity and the magnetic resistivity are of the same order, and a preconditioning method was used to allow the simulation of liquid metals, where these properties differ by several orders of magnitude. An extension of this method to the hydrodynamic equations allowed faster convergence to steady state. A new method of imposing boundary conditions using an extrapolation technique was derived, enabling the magnetic field at a boundary to be specified. Also, a technique by which the grid can be stretched was formulated to resolve thin layers at high imposed magnetic fields, allowing flows with Hartmann numbers of several thousand to be quickly and efficiently simulated. In addition, a module has been developed to calculate the temperature field and heat transfer. This uses a total variation diminishing scheme to solve the equations and is again very amenable to parallelisation. Although, the module was developed with thermal modelling in mind, it can also be applied to passive scalar transport. The code is fully three dimensional and has been applied to a wide variety of cases, including both laminar and turbulent flows. Validations against a series of canonical problems involving both MHD effects and turbulence have clearly demonstrated the ability of the LBM to properly model these types of flow. As well as applications to fusion engineering, the resulting code is flexible enough to be applied to a wide range of other flows, in particular those requiring parallel computations with many processors. For example, at
Measurement Of The Fluid Flow Load On A Globe Valve Stem Under Various Cavitation
Paris-Sud XI, UniversitÃ© de
Measurement Of The Fluid Flow Load On A Globe Valve Stem Under Various Cavitation Conditions)" #12;Measurement Of The Fluid Flow Load On A Globe Valve Stem Under Various Cavitation Conditions, cavitation, fluid flow load, CFD. Abstract: The evaluation of fluid forces on the stem is important for wear
Characterization of Filter Cake Buildup and Cleanup under Dynamic Fluid Loss Conditions
Yango, Takwe
2011-10-21T23:59:59.000Z
. The fracturing fluid gets dehydrated under pressure leaving behind a highly concentrated unbroken residue called filter cake which causes permeability impairment in the proppant pack, resulting in low fracture conductivity and decreased effective fracture length...
Two-fluid magnetic island dynamics in slab geometry: I -Isolated islands
Fitzpatrick, Richard
that there be zero net electromagnetic force acting on the island. Finally, the ion polarization current correction determination of the island phase-velocity, and the calculation of the ion and electron fluid flow profiles
Two-fluid magnetic island dynamics in slab geometry Richard Fitzpatrick
Fitzpatrick, Richard
. Moreover, the island propaga- tion velocity is uniquely specified by the condition that there be zero net determination of the island propagation velocity, and the calculation of the ion and electron fluid flow
Rotational dynamics of a superhelix towed in a Stokes fluid Sunghwan Jung
Fauci, Lisa
shaped bacteria that screw through viscous fluids due to the action of internal periplasmic flagella , we affected by a simple helical flagellum attached to and extruded from the cell body.3,6 Recently, there have
Dynamics and microstructure of colloidal complex fluids: a lattice Boltzmann study
Kim, Eunhye
2009-01-01T23:59:59.000Z
The lattice Boltzmann (LB) method is a versatile way to model complex fluids with hydrodynamic interactions through solving the Navier-Stokes equations. It is well-known that the role of hydrodynamic interactions is ...
Robert E. Spall; Barton Smith; Thomas Hauser
2008-12-08T23:59:59.000Z
Nationwide, the demand for electricity due to population and industrial growth is on the rise. However, climate change and air quality issues raise serious questions about the wisdom of addressing these shortages through the construction of additional fossil fueled power plants. In 1997, the President's Committee of Advisors on Science and Technology Energy Research and Development Panel determined that restoring a viable nuclear energy option was essential and that the DOE should implement a R&D effort to address principal obstacles to achieving this option. This work has addressed the need for improved thermal/fluid analysis capabilities, through the use of computational fluid dynamics, which are necessary to support the design of generation IV gas-cooled and supercritical water reactors.
Gasificaton Transport: A Multiphase CFD Approach & Measurements
Dimitri Gidaspow; Veeraya Jiradilok; Mayank Kashyap; Benjapon Chalermsinsuwan
2009-02-14T23:59:59.000Z
The objective of this project was to develop predictive theories for the dispersion and mass transfer coefficients and to measure them in the turbulent fluidization regime, using existing facilities. A second objective was to use our multiphase CFD tools to suggest optimized gasifier designs consistent with aims of Future Gen. We have shown that the kinetic theory based CFD codes correctly compute: (1) Dispersion coefficients; and (2) Mass transfer coefficients. Hence, the kinetic theory based CFD codes can be used for fluidized bed reactor design without any such inputs. We have also suggested a new energy efficient method of gasifying coal and producing electricity using a molten carbonate fuel cell. The principal product of this new scheme is carbon dioxide which can be converted into useful products such as marble, as is done very slowly in nature. We believe this scheme is a lot better than the canceled FutureGen, since the carbon dioxide is safely sequestered.
A 2-D Test Problem for CFD Modeling Heat Transfer in Spent Fuel Transfer Cask Neutron Shields
Zigh, Ghani; Solis, Jorge; Fort, James A.
2011-01-14T23:59:59.000Z
In the United States, commercial spent nuclear fuel is typically moved from spent fuel pools to outdoor dry storage pads within a transfer cask system that provides radiation shielding to protect personnel and the surrounding environment. The transfer casks are cylindrical steel enclosures with integral gamma and neutron radiation shields. Since the transfer cask system must be passively cooled, decay heat removal from spent nuclear fuel canister is limited by the rate of heat transfer through the cask components, and natural convection from the transfer cask surface. The primary mode of heat transfer within the transfer cask system is conduction, but some cask designs incorporate a liquid neutron shield tank surrounding the transfer cask structural shell. In these systems, accurate prediction of natural convection within the neutron shield tank is an important part of assessing the overall thermal performance of the transfer cask system. The large-scale geometry of the neutron shield tank, which is typically an annulus approximately 2 meters in diameter but only 5-10 cm in thickness, and the relatively small scale velocities (typically less than 5 cm/s) represent a wide range of spatial and temporal scales that contribute to making this a challenging problem for computational fluid dynamics (CFD) modeling. Relevant experimental data at these scales are not available in the literature, but some recent modeling studies offer insights into numerical issues and solutions; however, the geometries in these studies, and for the experimental data in the literature at smaller scales, all have large annular gaps that are not prototypic of the transfer cask neutron shield. This paper presents results for a simple 2-D problem that is an effective numerical analog for the neutron shield application. Because it is 2-D, solutions can be obtained relatively quickly allowing a comparison and assessment of sensitivity to model parameter changes. Turbulence models are considered as well as the tradeoff between steady state and transient solutions. Solutions are compared for two commercial CFD codes, FLUENT and STAR-CCM+. The results can be used to provide input to the CFD Best Practices for this application. Following study results for the 2-D test problem, a comparison of simulation results is provided for a high Rayleigh number experiment with large annular gap. Because the geometry of this validation is significantly different from the neutron shield, and due to the critical nature of this application, the argument is made for new experiments at representative scales
Content Dynamics in P2P Networks from Queueing and Fluid Perspectives.
Paganini Universidad ORT Uruguay, Montevideo, Uruguay Abstract--In this paper we analyze the dynamics of P2
Fabio Leoni; Giancarlo Franzese
2014-06-08T23:59:59.000Z
Confinement can modify the dynamics, the thermodynamics and the structural properties of liquid water, the prototypical anomalous liquid. By considering a general anomalous liquid, suitable for globular proteins, colloids or liquid metals, we study by molecular dynamics simulations the effect of a solvophilic structured and a solvophobic unstructured wall on the phases, the crystal nucleation and the dynamics of the fluid. We find that at low temperatures the large density of the solvophilic wall induces a high-density, high-energy structure in the first layer ("tempting" effect). In turn, the first layer induces a "molding" effect on the second layer determining a structure with reduced energy and density, closer to the average density of the system. This low-density, low-energy structure propagates further through the layers by templating effect and can involve all the existing layers at the lowest temperatures investigated. Therefore, although the high-density, high-energy structure does not self-reproduce further than the first layer, the structured wall can have a long-range effect thanks to a sequence of templating, molding and templating effects through the layers. We find dynamical slowing down of the solvent near the solvophilic wall but with largely heterogeneous dynamics near the wall due to superdiffusive liquid veins within a frozen matrix of solvent. Hence, the partial freezing of the first hydration layer does not correspond necessarily to an effective reduction of the channel section in terms of transport properties.
Real-time POD-CFD Wind-Load Calculator for PV Systems
Huayamave, Victor [Centecorp; Divo, Eduardo [Centecorp; Ceballos, Andres [Centecorp; Barriento, Carolina [Centecorp; Stephen, Barkaszi [FSEC; Hubert, Seigneur [FSEC
2014-03-21T23:59:59.000Z
The primary objective of this project is to create an accurate web-based real-time wind-load calculator. This is of paramount importance for (1) the rapid and accurate assessments of the uplift and downforce loads on a PV mounting system, (2) identifying viable solutions from available mounting systems, and therefore helping reduce the cost of mounting hardware and installation. Wind loading calculations for structures are currently performed according to the American Society of Civil Engineers/ Structural Engineering Institute Standard ASCE/SEI 7; the values in this standard were calculated from simplified models that do not necessarily take into account relevant characteristics such as those from full 3D effects, end effects, turbulence generation and dissipation, as well as minor effects derived from shear forces on installation brackets and other accessories. This standard does not include provisions that address the special requirements of rooftop PV systems, and attempts to apply this standard may lead to significant design errors as wind loads are incorrectly estimated. Therefore, an accurate calculator would be of paramount importance for the preliminary assessments of the uplift and downforce loads on a PV mounting system, identifying viable solutions from available mounting systems, and therefore helping reduce the cost of the mounting system and installation. The challenge is that although a full-fledged three-dimensional computational fluid dynamics (CFD) analysis would properly and accurately capture the complete physical effects of air flow over PV systems, it would be impractical for this tool, which is intended to be a real-time web-based calculator. CFD routinely requires enormous computation times to arrive at solutions that can be deemed accurate and grid-independent even in powerful and massively parallel computer platforms. This work is expected not only to accelerate solar deployment nationwide, but also help reach the SunShot Initiative goals of reducing the total installed cost of solar energy systems by 75%. The largest percentage of the total installed cost of solar energy system is associated with balance of system cost, with up to 40% going to “soft” costs; which include customer acquisition, financing, contracting, permitting, interconnection, inspection, installation, performance, operations, and maintenance. The calculator that is being developed will provide wind loads in real-time for any solar system designs and suggest the proper installation configuration and hardware; and therefore, it is anticipated to reduce system design, installation and permitting costs.
Chen, X. [Centre for Theoretical Cosmology, DAMTP, University of Cambridge, Cambridge CB3 0WA (United Kingdom); Firouzjahi, H. [School of Astronomy, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of); Namjoo, M.H. [School of Physics, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran (Iran, Islamic Republic of); Sasaki, M., E-mail: x.chen@damtp.cam.ac.uk, E-mail: firouz@ipm.ir, E-mail: mh.namjoo@ipm.ir, E-mail: misao@yukawa.kyoto-u.ac.jp [Yukawa Institute for theoretical Physics, Kyoto University, Kyoto 606-8502 (Japan)
2013-09-01T23:59:59.000Z
In this work we present an inflationary mechanism based on fluid dynamics. Starting with the action for a single barotropic perfect fluid, we outline the procedure to calculate the power spectrum and the bispectrum of the curvature perturbation. It is shown that a perfect barotropic fluid naturally gives rise to a non-attractor inflationary universe in which the curvature perturbation is not frozen on super-horizon scales. We show that a scale-invariant power spectrum can be obtained with the local non-Gaussianity parameter f{sub NL} = 5/2.
Under consideration for publication in J. Fluid Mech. 1 Dynamics of Bead Formation,
evolution it is possible to extract transient extensional viscosity information even for very low viscosity the instability and breakup of polymeric jets is important for a wide variety of applications including spraying- stable when compared to a Newtonian fluid of the same viscosity and inertia (Middleman (1965), Goldin et
Accelerating Fast Fluid Dynamics with a Coarse-grid Projection Scheme Mingang Jin, Qingyan Chen*
Chen, Qingyan "Yan"
applications, such as emergency management, fast design of sustainable buildings, and development of integrated for providing fast and informative building airflow simulations. Initially designed for visualizing fluid flow model that can provide fast and informative building airflow simulations. Although reasonably good
Yang, Cher-Chiang
2008-05-05T23:59:59.000Z
............................................................................................................... 25 3.2.4. Starting FlowLab ...................................................................................................................... 26 3.2.5. Geometry Settings... OF THE PROGRAMMING....................................................................... 52 v List of Figures FIGURE 2.1 ? COST AND TIME RELATIONSHIP WITH RESPECT TO CFD AND WIND TUNNELS............................. 5 FIGURE 2.2 - BOEING 777 DESIGN...
Frisani, Angelo
2011-08-08T23:59:59.000Z
the VHTR performance and safety analysis, one-dimensional (1-D) system type codes, like RELAP5 or MELCOR, and multi-dimensional CFD codes can be used. The choice of 1-D over multi-dimensional codes first involves identifying the main phenomena, and from...
CFD-based Optimization for Automotive Aerodynamics
Dumas, Laurent
Chapter 1 CFD-based Optimization for Automotive Aerodynamics Laurent Dumas Abstract The car drag- ments. An overview of the main characteristics of automotive aerodynamics and a detailed presentation.dumas@upmc.fr) 1 #12;2 Laurent Dumas 1.1 Introducing Automotive Aerodynamics 1.1.1 A Major Concern for Car
Solom, Matthew 1985-
2012-12-10T23:59:59.000Z
of laser-induced cavitation in a seeded fluid, and demonstrated some of the associated limitations as well. In addition, the CFD framework developed here can be used to cross-compare experimental results with computer simulations as well...
Morgen, M.M. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry; [Lawrence Berkeley National Lab., CA (United States)
1997-05-01T23:59:59.000Z
We develop a polarization-sensitive femtosecond pump probe technique, Raman induced polarization spectroscopy (RIPS), to study coherent rotation in molecular fluids. By observing the collisional dephasing of the coherently prepared rotational states, we are able to extract information concerning the effects of molecular interactions on the rotational motion. The technique is quite sensitive because of the zero background detection method, and is also versatile due to its nonresonant nature.
Leoni, Fabio; Franzese, Giancarlo [Departament de Fisica Fonamental, Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona (Spain)
2014-11-07T23:59:59.000Z
Confinement can modify the dynamics, the thermodynamics, and the structural properties of liquid water, the prototypical anomalous liquid. By considering a generic model for anomalous liquids, suitable for describing solutions of globular proteins, colloids, or liquid metals, we study by molecular dynamics simulations the effect that an attractive wall with structure and a repulsive wall without structure have on the phases, the crystal nucleation, and the dynamics of the fluid. We find that at low temperatures the large density of the attractive wall induces a high-density, high-energy structure in the first layer (“templating” effect). In turn, the first layer induces a “molding” effect on the second layer determining a structure with reduced energy and density, closer to the average density of the system. This low-density, low-energy structure propagates further through the layers by templating effect and can involve all the existing layers at the lowest temperatures investigated. Therefore, although the high-density, high-energy structure does not self-reproduce further than the first layer, the structured wall can have a long-range influence thanks to a sequence of templating, molding, and templating effects through the layers. We find that the walls also have an influence on the dynamics of the liquid, with a stronger effect near the attractive wall. In particular, we observe that the dynamics is largely heterogeneous (i) among the layers, as a consequence of the sequence of structures caused by the walls presence, and (ii) within the same layer, due to superdiffusive liquid veins within a frozen matrix of particles near the walls at low temperature and high density. Hence, the partial freezing of the first layer does not correspond necessarily to an effective reduction of the channel's section in terms of transport properties, as suggested by other authors.
Bonneville Powerhouse 2 3D CFD for the Behavioral Guidance System
Rakowski, Cynthia L.; Richmond, Marshall C.; Serkowski, John A.
2010-02-01T23:59:59.000Z
In 2008 and 2009, a 700 ft long, 10-ft deep floating forebay guidance wall called a behavioral guidance structure (BGS) was deployed in the Bonneville Powerhouse 2 forebay. The US Army Corps of Engineers, Portland District (CENWP) contracted with the Pacific Northwest National Laboratory (PNNL) to develop computational tools to assess the impact of the BGS on forebay hydraulics (this study). The tools developed here to provide a characterization of forebay hydraulics to be integrated with acoustic telemetry studies designed to measure the impact on juvenile salmon guidance and survival through Bonneville Powerhouse 2. In previous work, PNNL performed computational fluid dynamics (CFD) studies for the Bonneville forebay for CENWP. In this study, the existing model was modified to include the BGS. The model included a bay-by-bay spillway, a truncated Powerhouse 1 forebay, Powerhouse 2 turbine intakes and corner collector, and the forebay bathymetry extending approximately 1.5km upstream from the tip of Cascade Island. Model validation outcomes were similar to that of past studies. Additional checks were included on the impact of the differencing scheme to flow solution. It was found that using upwind differencing was adequate and it was possible to use a truncated computational mesh of this model that included a BGS upstream of Powerhouse 2 and increased spatial resolution in the vicinity of the BGS. This model has been validated, run, and provided to CENWP to use for additional analysis of the Powerhouse 2 forebay hydraulics. The PNNL particle tracking software (PT6) was used to assess the impacts of mass and relative buoyancy on particle fate. The particle tracker was run for the Half Load case for the clean forebay and for the forebay with the BGS in place and the Corner Collector on. All tracker cases showed that the BGS moved the particles across the forebay increasing the number of particles exiting the model through the Corner Collector and (for streamlines and neutrally-buoyant particles) the lower numbered turbine units.
MODELING STRATEGIES TO COMPUTE NATURAL CIRCULATION USING CFD IN A VHTR AFTER A LOFA
Yu-Hsin Tung; Richard W. Johnson; Ching-Chang Chieng; Yuh-Ming Ferng
2012-11-01T23:59:59.000Z
A prismatic gas-cooled very high temperature reactor (VHTR) is being developed under the next generation nuclear plant program (NGNP) of the U.S. Department of Energy, Office of Nuclear Energy. In the design of the prismatic VHTR, hexagonal shaped graphite blocks are drilled to allow insertion of fuel pins, made of compacted TRISO fuel particles, and coolant channels for the helium coolant. One of the concerns for the reactor design is the effects of a loss of flow accident (LOFA) where the coolant circulators are lost for some reason, causing a loss of forced coolant flow through the core. In such an event, it is desired to know what happens to the (reduced) heat still being generated in the core and if it represents a problem for the fuel compacts, the graphite core or the reactor vessel (RV) walls. One of the mechanisms for the transport of heat out of the core is by the natural circulation of the coolant, which is still present. That is, how much heat may be transported by natural circulation through the core and upwards to the top of the upper plenum? It is beyond current capability for a computational fluid dynamic (CFD) analysis to perform a calculation on the whole RV with a sufficiently refined mesh to examine the full potential of natural circulation in the vessel. The present paper reports the investigation of several strategies to model the flow and heat transfer in the RV. It is found that it is necessary to employ representative geometries of the core to estimate the heat transfer. However, by taking advantage of global and local symmetries, a detailed estimate of the strength of the resulting natural circulation and the level of heat transfer to the top of the upper plenum is obtained.
Rahatgaonkar, P. S.; Datta, D.; Malhotra, P. K.; Ghadge, S. G. [Nuclear Power Corporation of India Ltd., R-2, Ent. Block, Nabhikiya Urja Bhavan, Anushakti Nagar, Mumbai - 400 094 (India)
2012-07-01T23:59:59.000Z
Prediction of groundwater movement and contaminant transport in soil is an important problem in many branches of science and engineering. This includes groundwater hydrology, environmental engineering, soil science, agricultural engineering and also nuclear engineering. Specifically, in nuclear engineering it is applicable in the design of spent fuel storage pools and waste management sites in the nuclear power plants. Ground water modeling involves the simulation of flow and contaminant transport by groundwater flow. In the context of contaminated soil and groundwater system, numerical simulations are typically used to demonstrate compliance with regulatory standard. A one-dimensional Computational Fluid Dynamics code GFLOW had been developed based on the Finite Difference Method for simulating groundwater flow and contaminant transport through saturated and unsaturated soil. The code is validated with the analytical model and the benchmarking cases available in the literature. (authors)
Picosecond spectroscopy and solvation clusters. The dynamics of localizing electrons in polar fluids
Kenney-Wallace, G.A. (Univ. of Toronto, Ontario); Jonah, C.D.
1982-07-08T23:59:59.000Z
New spectroscopic evidence concerning the dynamics of electron-induced solvation clusters in polar liquids is presented and integrated with previous picosecond data, in order to outline the roles molecular dynamics and structure can play both in initiating electron localization at subpicosecond times and in governing the solvation dynamics to form e/sup -//sub s/ in the picosecond domain. Particulr emphasis is placed on the picosecond time-resolved absorption spectroscopy of electrons in a wide range of alcohols and alcohol-alkane systems at 300/sup 0/K as a framework for the cluster model of electron solvation. While the configurationally relaxed final quantum state of e/sup -//sub s/ appears identical for e/sup -//sub s/ generated by different techniques, it is possible that the time evolution of the solvation cluster and the dynamics of electron populations between localized and continuum states could be influenced by the initial state of the system. Selected examples are discussed for alcohols, amines, and water, and comparisons are made for picosecond observations from different visible and IR spectroscopic techniques, NMR, and complementary nanosecond electron mobility data to demonstrate the overall consistency of a model in which only the dynamical, microscopic properties of the liquid determine these solvation events.
Relaxation dynamics in a transient network fluid with competing gel and glass phases
Pinaki Chaudhuri; Pablo I. Hurtado; Ludovic Berthier; Walter Kob
2015-02-01T23:59:59.000Z
We use computer simulations to study the relaxation dynamics of a model for oil-in-water microemulsion droplets linked with telechelic polymers. This system exhibits both gel and glass phases and we show that the competition between these two arrest mechanisms can result in a complex, three-step decay of the time correlation functions, controlled by two different localization lengthscales. For certain combinations of the parameters, this competition gives rise to an anomalous logarithmic decay of the correlation functions and a subdiffusive particle motion, which can be understood as a simple crossover effect between the two relaxation processes. We establish a simple criterion for this logarithmic decay to be observed. We also find a further logarithmically slow relaxation related to the relaxation of floppy clusters of particles in a crowded environment, in agreement with recent findings in other models for dense chemical gels. Finally, we characterize how the competition of gel and glass arrest mechanisms affects the dynamical heterogeneities and show that for certain combination of parameters these heterogeneities can be unusually large. By measuring the four-point dynamical susceptibility, we probe the cooperativity of the motion and find that with increasing coupling this cooperativity shows a maximum before it decreases again, indicating the change in the nature of the relaxation dynamics. Our results suggest that compressing gels to large densities produces novel arrested phases that have a new and complex dynamics.
CFD Solvers on Many-core Processors
Brandvik, Tobias
2008-11-11T23:59:59.000Z
cores with 4 · 106 transistors each gives 10 times the performance as 1 big core 0 0.5 1 1.5 2 2.5 3 3.5 4 x 108Number of transistors P e r f o r m a n c e CFD Solvers on Many-core Processors – p.8/36 Everyone is going parallel Every major chip vendor... on Many-core Processors – p.22/36 Stencil operations Evaluate ?2u?x2 on a regular grid: DO K=2,NK-1 DO J=2,NJ-1 DO I=2,NI-1 D2UDX2(I,J,K) = (U(I+1,J,K) - 2.0*U(I,J,K) + & U(I-1,J,K))/(DX*DX) END DO END DO END DO CFD Solvers on Many-core Processors – p.23...
Fluid Dynamics Seminar Fluid Dynamics Research Centre
Davies, Christopher
(Department of Engineering, University of Liverpool) 24 th May Cavitation, a Possible Cause of Damage to Three Gorge Turbines? Prof. Shengcai C. Li. (Professor of Hydraulic Machinery, based at the School
Fluid Dynamics Seminar Fluid Dynamics Research Centre
Davies, Christopher
(Department of Engineering, University of Liverpool) 24th May Cavitation, a Possible Cause of Damage to Three Gorge Turbines? Prof. Shengcai C. Li. (Professor of Hydraulic Machinery, based at the School
L-H transition dynamics in fluid turbulence simulations with neoclassical force balance
Chôné, L. [Aix–Marseille Université, CNRS, PIIM UMR 7345, 13397 Marseille Cedex 20 (France); CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France); Beyer, P.; Fuhr, G.; Benkadda, S. [Aix–Marseille Université, CNRS, PIIM UMR 7345, 13397 Marseille Cedex 20 (France); Sarazin, Y.; Bourdelle, C. [CEA, IRFM, F-13108 Saint-Paul-lez-Durance (France)
2014-07-15T23:59:59.000Z
Spontaneous transport barrier generation at the edge of a magnetically confined plasma is reproduced in flux-driven three-dimensional fluid simulations of electrostatic turbulence. Here, the role on the radial electric field of collisional friction between trapped and passing particles is shown to be the key ingredient. Especially, accounting for the self-consistent and precise dependence of the friction term on the actual plasma temperature allows for the triggering of a transport barrier, provided that the input power exceeds some threshold. In addition, the barrier is found to experience quasi-periodic relaxation events, reminiscent of edge localised modes. These results put forward a possible key player, namely, neoclassical physics via radial force balance, for the low- to high-confinement regime transition observed in most of controlled fusion devices.
Fisher, Andrew
records of formation properties The addition of logging while drilling technology where logging tools to exciting scientific discoveries through ocean drilling Essentially all studies of fluid flow within for new approaches or techniques The following highlights selected from recent studies of seafloor fluids
Paris-Sud XI, Université de
THIESEL 2010 Conference on Thermo- and Fluid Dynamic Processes in Diesel Engines Influence of Nozzle Geometry on Spray Shape, Particle Size, Spray Velocity and Air Entrainment of High Pressure Diesel Abstract. Air/fuel mixing process in the combustion chamber of Diesel engines plays an important role
CFD Analysis of Particle Deposition During DPF Filtration Processes...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Processes CFD Analysis of Particle Deposition During DPF Filtration Processes A 3-D DPF model is developed to predict thermo-physical properties during filtration processes and to...
CFD Combustion Modeling with Conditional Moment Closure using...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Combustion Modeling with Conditional Moment Closure using Tabulated Chemistry CFD Combustion Modeling with Conditional Moment Closure using Tabulated Chemistry A method is...
The potential energy landscape and inherent dynamics of a hard-sphere fluid
Qingqing Ma; Richard M. Stratt
2014-08-13T23:59:59.000Z
Hard-sphere models exhibit many of the same kinds of supercooled-liquid behavior as more realistic models of liquids, but the highly non-analytic character of their potentials makes it a challenge to think of that behavior in potential-energy-landscape terms. We show here that it is possible to calculate an important topological property of hard-sphere landscapes, the geodesic pathways through those landscapes, and to do so without artificially coarse-graining or softening the potential. We show, moreover, that the rapid growth of the lengths of those pathways with increasing packing fraction quantitatively predicts the precipitous decline in diffusion constants in a glass-forming hard-sphere mixture model. The geodesic paths themselves can be considered as defining the intrinsic dynamics of hard spheres, so it is also revealing to find that they (and therefore the features of the underlying potential-energy landscape) correctly predict the occurrence of dynamic heterogeneity and non-zero values of the non-Gaussian parameter. The success of these landscape predictions for the dynamics of such a singular model emphasizes that there is more to potential energy landscapes than is revealed by looking at the minima and saddle points.
Derivation of Covariant Dissipative Fluid Dynamics in the Renormalization-group Method
K. Tsumura; T. Kunihiro; K. Ohnishi
2006-12-29T23:59:59.000Z
We derive generic relativistic hydrodynamical equations with dissipative effects from the underlying Boltzmann equation in a mechanical and systematic way on the basis of so called the renormalization-group (RG) method. A macroscopic frame vector is introduced to specify the frame on which the macroscopic dynamics is described. Our method is so mechanical with only few ansatz that our method give a microscopic foundation of the available hydrodynamical equations, and also can be applied to make a reduction of the kinetic equations other than the simple Boltzmann equation.
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Laboratory Collection: Engineering 14 Solution characters of iterative coupling between energy simulation and CFD programs Summary: type of airflow models. CFD predicts the...
Some thoughts on exploiting CFD for turbomachinery design
Giles, Mike
Some thoughts on exploiting CFD for turbomachinery design M. B. Giles Oxford University Computing enormously and it is now used extensively by all turbomachinery companies in designing speci c components was presented at the IMeche Symposium on Exploiting CFD for Turbomachinery Design, on March 19th, 1998
CFD simulation of neutral ABL flows Xiaodong Zhang
Title: CFD simulation of neutral ABL flows Division: Aero-elastic Design Â Wind Energy Division RisÃ¸ flow field over different terrains employing Fluent 6.3 software. How accurate the simulation could.5 Comparison and conclusion 22 3.6 Closure 24 4 CFD Simulation of the Askervein Hill 24 4.1 Simulation
3457, Page, 1 Coupled CFD/Building Envelope Model
Gugercin, Serkan
Performance Buildings Conference at Purdue, 2012 (Accepted) #12;3457, Page, 2 a standard model for a single3457, Page, 1 Coupled CFD/Building Envelope Model for the Purdue Living Lab Donghun KIM (kim1077 features. In the present case we develop a procedure for coupling a building envelope model to a CFD
Davis, Michael A.
2011-10-21T23:59:59.000Z
the harmonics generated by ECM systems. All research objectives were achieved. The CFD model, which was verified with laboratory measurements, showed the potential to identify opportunities for improvement in the design of the FPTU and accurately predicted...
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Summary: , European Conference on Computational Fluid Dynamics, TU Delft, Delft The Netherland, 2006. D. Lazzara (MIT... Dynamics Research, No. AIAA 99-3798, AIAA Fluid Dynamics...
Fluid Flow Modeling in Fractures
Sarkar, Sudipta
2004-01-01T23:59:59.000Z
In this paper we study fluid flow in fractures using numerical simulation and address the challenging issue of hydraulic property characterization in fractures. The methodology is based on Computational Fluid Dynamics, ...
-water' balance in a homogeneous fluid. The MASS conservation equation for a constant density fluid implies.1-7.6 (began last week), 10.4 (Kelvin waves) (similar material in Vallis Â§Â§ 2.8, 3.1, 3.6-3.8 Bretherton than a fraction of a wavelength. This is implicit in a scale analysis of the governing equation
data, the levels of noise in flight and in wind tunnels, and how noise levels can affect parametric requirements for gas-turbine-engine blades and vanes, low-Reynolds-number vehicles, submarines and torpedoes of view. Also included is a review of wind-tunnel and flight data, including high-Re flight transition
Paris-Sud XI, UniversitÃ© de
spaced, vertical glass plates. Such a "rivulet" is bounded by two liquid/solid and two mobile liquid/gas interfaces, posing fluid dynamic problems of direct relevance to local fluid flow in liquid foams/liquid or liquid/gas interfaces, as found in foams and emulsions, which respond to flow by adjusting their shape
Bianco, Ronald
2013-12-02T23:59:59.000Z
have an increased localization toward the boundaries of the gouge layer (type III), and no occurrence of distributed (type I) shear. Systems with lower N and k show liquefaction events. Liquefaction events originate from increases in fluid pressure...
Haghshenas, Arash
2013-04-24T23:59:59.000Z
The worst scenario of drilling operation is blowout which is uncontrolled flow of formation fluid into the wellbore. Blowouts result in environmental damage with potential risk of injuries and fatalities. Although not all blowouts result in disaster...
Rakowski, Cynthia L.; Serkowski, John A.; Richmond, Marshall C.; Perkins, William A.
2010-12-01T23:59:59.000Z
In 2003, an extension of the existing ice and trash sluiceway was added at Bonneville Powerhouse 2 (B2). This extension started at the existing corner collector for the ice and trash sluiceway adjacent to Bonneville Powerhouse 2 and the new sluiceway was extended to the downstream end of Cascade Island. The sluiceway was designed to improve juvenile salmon survival by bypassing turbine passage at B2, and placing these smolt in downstream flowing water minimizing their exposure to fish and avian predators. In this study, a previously developed computational fluid dynamics model was modified and used to characterized tailrace hydraulics and sluiceway egress conditions for low total river flows and low levels of spillway flow. STAR-CD v4.10 was used for seven scenarios of low total river flow and low spill discharges. The simulation results were specifically examined to look at tailrace hydraulics at 5 ft below the tailwater elevation, and streamlines used to compare streamline pathways for streamlines originating in the corner collector outfall and adjacent to the outfall. These streamlines indicated that for all higher spill percentage cases (25% and greater) that streamlines from the corner collector did not approach the shoreline at the downstream end of Bradford Island. For the cases with much larger spill percentages, the streamlines from the corner collector were mid-channel or closer to the Washington shore as they moved downstream. Although at 25% spill at 75 kcfs total river, the total spill volume was sufficient to "cushion" the flow from the corner collector from the Bradford Island shore, areas of recirculation were modeled in the spillway tailrace. However, at the lowest flows and spill percentages, the streamlines from the B2 corner collector pass very close to the Bradford Island shore. In addition, the very flow velocity flows and large areas of recirculation greatly increase potential predator exposure of the spillway passed smolt. If there is concern for egress issues for smolt passing through the spillway, the spill pattern and volume need to be revisited.
Evaluation of a CFD-model for simulation of simplified flow conditioners
Erdal, A. [Statoil/K-LAB, Haugesund (Norway); Torbergsen, L.E.; Rimestad, S.; Krogstad, P.A. [Norwegian Inst. of Technology, Trondheim (Norway)
1995-12-31T23:59:59.000Z
Perforated plate flow conditioners are used to generate a fully developed turbulent flow profile upstream of an orifice meter. It is very time-consuming to measure the effect of a flow conditioner for different upstream flow profiles. Therefore a project is initiated to evaluate the performance of a computational fluid computer code for this purpose. If the code correctly predicts the flow characteristics downstream of more complex flow conditioners. In this study a k-{var_epsilon} CFD-model was used to predict the flow downstream of obstruction plates having one large or nine small holes. Both mean velocity, turbulent kinetic energy, k, and the dissipation rate of turbulent kinetic energy, {var_epsilon}, were calculated and compared against measured data. The results indicate that it is possible to predict the mean velocity well and that the accuracy of the predicted k and {var_epsilon} depends on the complexity of the flow.
Ahuja, Vivek
2008-01-01T23:59:59.000Z
??A new methodology for the optimization of fuel-air mixing in a scramjet combustor using integrated Genetic Algorithms and Computational Fluid Dynamics is presented. A typical… (more)
Aerodynamic Shape Design of Transonic Airfoils Using Hybrid Optimization Techniques and CFD
Xing, X.Q.
This paper will analyze the effects of using hybrid optimization methods for optimizing objective functions that are determined by computational fluid dynamics solvers for compressible viscous flow for optimal design of ...
Ewa Graczynska; Dietmar Schweigert
2005-07-01T23:59:59.000Z
We invent the notion of a derived and fluid variety. Fluid variety has no proper derived variety as its subvariety. We examine some properties of fluid and derived varieties. Examples of such varieties of bands are presented.
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Thermal Fluids The Thermal Fluids and Heat Transfer program works on thermal hydraulic reactor safety code development and experimental heat transferthermal hydraulics. The...
Petascale, Adaptive CFD | Argonne Leadership Computing Facility
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demonstrated to restore and maintain flow attachment and reduce vibrations in wind turbine blades during dynamic pitch, thereby reducing unsteady loads on gearboxes that are...
Optimization of a Two-Fluid Hydrodynamic Model of Churn-Turbulent Flow
Donna Post Guillen
2009-07-01T23:59:59.000Z
A hydrodynamic model of two-phase, churn-turbulent flows is being developed using the computational multiphase fluid dynamics (CMFD) code, NPHASE-CMFD. The numerical solutions obtained by this model are compared with experimental data obtained at the TOPFLOW facility of the Institute of Safety Research at the Forschungszentrum Dresden-Rossendorf. The TOPFLOW data is a high quality experimental database of upward, co-current air-water flows in a vertical pipe suitable for validation of computational fluid dynamics (CFD) codes. A five-field CMFD model was developed for the continuous liquid phase and four bubble size groups using mechanistic closure models for the ensemble-averaged Navier-Stokes equations. Mechanistic models for the drag and non-drag interfacial forces are implemented to include the governing physics to describe the hydrodynamic forces controlling the gas distribution. The closure models provide the functional form of the interfacial forces, with user defined coefficients to adjust the force magnitude. An optimization strategy was devised for these coefficients using commercial design optimization software. This paper demonstrates an approach to optimizing CMFD model parameters using a design optimization approach. Computed radial void fraction profiles predicted by the NPHASE-CMFD code are compared to experimental data for four bubble size groups.
How to use CFD for Wind in Terrain ... real-life experience!
: · Turbulence modelling / numerical methods · Inclusion of wind turbine wake · Temperature stratification 2 study 3. Construction and operation 4. Wind turbine breakdown! 5. Wind measurements / CFD simulations1 How to use CFD for Wind in Terrain ... real-life experience! CFD day at Suzlon, October 2007 A
The Dynamic Compressive Response of an Open-Cell Foam Impregnated With a Non-Newtonian Fluid
Dawson, Matthew A.
The response of a reticulated, elastomeric foam filled with colloidal silica under dynamic compression is studied. Under compression beyond local strain rates on the order of 1 s[superscript ?1], the non-Newtonian, colloidal ...
Goel, Piyush
2010-10-12T23:59:59.000Z
A Web-server farm is a specialized facility designed specifically for housing Web servers catering to one or more Internet facing Web sites. In this dissertation, stochastic dynamic programming technique is used to obtain the optimal admission...
Ris-R-1465(EN) CFD Computations of
Risø-R-1465(EN) CFD Computations of Wind Turbine Blade Loads During Standstill Operation KNOW-BLADE on parked wind turbine blades. Investigation of loads during parked conditions, was done by other authors] investigated parking loads on a 2.4 meter wind turbine blade in a wind tunnel, and the recent large scale
Barney, G.S.
1996-09-27T23:59:59.000Z
This report presents an in-depth review of the potential for nuclear criticality to occur in Hanford defense waste tanks during past, current and future safe storage and maintenance operations. The report also briefly discusses the potential impacts of proposed retrieval activities, although retrieval was not a main focus of scope. After thorough review of fluid dynamic aspects that focus on particle segregation, chemical aspects that focus on solubility and adsorption processes that might concentrate plutonium and/or separate plutonium from the neutron absorbers in the tank waste, and ore-body formation and mining operations, the interdisciplinary team has come to the conclusion that there is negligible risk of nuclear critically under existing storage conditions in Hanford site underground waste storage tanks. Further, for the accident scenarios considered an accidental criticality is incredible.
Benitz, M. A.; Schmidt, D. P.; Lackner, M. A.; Stewart, G. M.; Jonkman, J.; Robertson, A.
2014-09-01T23:59:59.000Z
Hydrodynamic loads on the platforms of floating offshore wind turbines are often predicted with computer-aided engineering tools that employ Morison's equation and/or potential-flow theory. This work compares results from one such tool, FAST, NREL's wind turbine computer-aided engineering tool, and the computational fluid dynamics package, OpenFOAM, for the OC4-DeepCwind semi-submersible analyzed in the International Energy Agency Wind Task 30 project. Load predictions from HydroDyn, the offshore hydrodynamics module of FAST, are compared with high-fidelity results from OpenFOAM. HydroDyn uses a combination of Morison's equations and potential flow to predict the hydrodynamic forces on the structure. The implications of the assumptions in HydroDyn are evaluated based on this code-to-code comparison.
Quantifying the stimuli of photorheological fluids
Bates, Sarah Woodring
2010-01-01T23:59:59.000Z
We develop a model to predict the dynamics of photorheological fluids and, more generally, photoresponsive fluids for monochromatic and polychromatic light sources. Derived from first principles, the model relates the ...
Yildiz, B.; Smith, J.; Sofu, T.; Nuclear Engineering Division
2008-06-25T23:59:59.000Z
Argonne National Laboratory and Idaho National Laboratory researchers are analyzing the electrochemical and thermal-fluid behavior of solid oxide electrolysis cells (SOECs) for high temperature steam electrolysis using computational fluid dynamics (CFD) techniques. The major challenges facing commercialization of steam electrolysis technology are related to efficiency, cost, and durability of the SOECs. The goal of this effort is to guide the design and optimization of performance for high temperature electrolysis (HTE) systems. An SOEC module developed by FLUENT Inc. as part of their general CFD code was used for the SOEC analysis by INL. ANL has developed an independent SOEC model that combines the governing electrochemical mechanisms based on first principals to the heat transfer and fluid dynamics in the operation of SOECs. The ANL model was embedded into the commercial STAR-CD CFD software, and is being used for the analysis of SOECs by ANL. The FY06 analysis performed by ANL and reported here covered the influence of electrochemical properties, SOEC component resistances and their contributing factors, SOEC size and inlet flow conditions, and SOEC flow configurations on the efficiency and expected durability of these systems. Some of the important findings from the ANL analysis are: (1) Increasing the inlet mass flux while going to larger cells can be a compromise to overcome increasing thermal and current density gradients while increasing the cell size. This approach could be beneficial for the economics of the SOECs; (2) The presence of excess hydrogen at the SOEC inlet to avoid Ni degradation can result in a sizeable decrease in the process efficiency; (3) A parallel-flow geometry for SOEC operation (if such a thing be achieved without sealing problems) yields smaller temperature gradients and current density gradients across the cell, which is favorable for the durability of the cells; (4) Contact resistances can significantly influence the total cell resistance and cell temperatures over a large range of operating potentials. Thus it is important to identify and avoid SOEC stack conditions leading to such high resistances due to poor contacts.
Considering value of information when using CFD in design
Misra, John Satprim
2009-12-19T23:59:59.000Z
This thesis presents an approach to find lower resolution CFD models that can accurately lead a designer to a correct decision at a lower computational cost. High-fidelity CFD models often contain too much information and come at a higher computational cost, limiting the designs a designer can test and how much optimization can be performed on the design. Lower model resolution is commonly used to reduce computational time. However there are no clear guidelines on how much model accuracy is required. Instead experience and intuition are used to select an appropriate lower resolution model. This thesis presents an alternative to this ad hoc method by considering the added value of the addition information provided by increasing accurate and more computationally expensive models.
FRACTURING FLUID CHARACTERIZATION FACILITY
Subhash Shah
2000-08-01T23:59:59.000Z
Hydraulic fracturing technology has been successfully applied for well stimulation of low and high permeability reservoirs for numerous years. Treatment optimization and improved economics have always been the key to the success and it is more so when the reservoirs under consideration are marginal. Fluids are widely used for the stimulation of wells. The Fracturing Fluid Characterization Facility (FFCF) has been established to provide the accurate prediction of the behavior of complex fracturing fluids under downhole conditions. The primary focus of the facility is to provide valuable insight into the various mechanisms that govern the flow of fracturing fluids and slurries through hydraulically created fractures. During the time between September 30, 1992, and March 31, 2000, the research efforts were devoted to the areas of fluid rheology, proppant transport, proppant flowback, dynamic fluid loss, perforation pressure losses, and frictional pressure losses. In this regard, a unique above-the-ground fracture simulator was designed and constructed at the FFCF, labeled ''The High Pressure Simulator'' (HPS). The FFCF is now available to industry for characterizing and understanding the behavior of complex fluid systems. To better reflect and encompass the broad spectrum of the petroleum industry, the FFCF now operates under a new name of ''The Well Construction Technology Center'' (WCTC). This report documents the summary of the activities performed during 1992-2000 at the FFCF.
Supersymmetric Fluid Mechanics
R. Jackiw; A. P. Polychronakos
2000-07-17T23:59:59.000Z
When anticommuting Grassmann variables are introduced into a fluid dynamical model with irrotational velocity and no vorticity, the velocity acquires a nonvanishing curl and the resultant vorticity is described by Gaussian potentials formed from the Grassmann variables. Upon adding a further specific interaction with the Grassmann degrees of freedom, the model becomes supersymmetric.
interacting with one another). Or, even the generation of non-geostrophic fronts and waves through flow March 2011 Stratified, rotating fluid: thermal wind and stratified geostrophic adjustment to geostrophic.7 and Bernoulli equation 4.8 Geostrophic adjustment in a 1-layer fluid with a free surface: notes The idealized
A Multiscale Analysis of Dynamic Wetting
Minaki, Hiroyuki
2013-01-01T23:59:59.000Z
Williams, B. C. (2008). Engineering Fluid Mechanics. Wiley,Thermo-Fluid Dynamics: In Materials Science and Engineering.Fluid Dynamics. McGraw-Hill Sci- ence/Engineering/Math, 1st
E-Print Network 3.0 - advanced cfd codes Sample Search Results
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Laboratory Collection: Engineering 13 Solution characters of iterative coupling between energy simulation and CFD programs Summary: 1 Solution characters of iterative coupling...
Kelley, N.D.
1993-11-01T23:59:59.000Z
We have recently shown that the alternating load fatigue distributions measured at several locations on a wind turbine operating in a turbulent flow can be described by a mixture of at least three parametric statistical models. The rainflow cycle counting of the horizontal and vertical inflow components results in a similar mixture describing the cyclic content of the wind. We believe such a description highlights the degree of non-Gaussian characteristics of the flow. We present evidence that the severity of the low-cycle, high-amplitude alternating stress loads seen by wind turbine components are a direct consequence of the degree of departure from normality in the inflow. We have examined the details of the turbulent inflow associated with series large loading events that took place on two adjacent wind turbines installed in a large wind park in San Gorgonio Pass, California. In this paper, we describe what we believe to be the agents in the flow that induced such events. We also discuss the atmospheric mechanisms that influence the low-cycle, high-amplitude range loading seen by a number of critical wind turbine components. We further present results that can be used to scale the specific distribution shape as functions of measured inflow fluid dynamics parameters.
E-Print Network 3.0 - air contamination due Sample Search Results
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Experimental Validation of a Computational Fluid Dynamics Model for IAQ applications in Ice Rink Arenas Summary: dynamics (CFD) model has been used to predict the contaminant...
Numerical simulation of flow distribution for pebble bed high temperature gas cooled reactors
Yesilyurt, Gokhan
2004-09-30T23:59:59.000Z
?....................................................................................26 V CFD MODELLING ...................................................................................28 V.1 Computational Fluid Dynamics (CFD) ..........................................28 V.2 The History.... Hassan The premise of the work presented here is to use a common analytical tool, Computational Fluid Dynamics (CFD), along with different turbulence models. Eddy viscosity models as well as state-of-the-art Large Eddy Simulation (LES) were...
Hajdukiewicz, M.; Keane, M.; O'Flynn, B.; O'Grady, W.
2010-01-01T23:59:59.000Z
controlled internal environments. In this research a CFD model of the internal environment of an office space will be developed. The CFD model will then be calibrated using real data taken from a well-positioned wireless sensor network and weather station...
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CITIZENSHIP Summary: , Kavli Institute for Theoretical Physics, UCSB, Feb.-Mar. 2000. Fluids Engineering Award, ASME, 2000... . Fluid Dynamics Award, AIAA, 2002. 12;4 His...
Alexios P. Polychronakos
2007-06-27T23:59:59.000Z
We review the connection between noncommutative gauge theory, matrix models and fluid mechanical systems. The noncommutative Chern-Simons description of the quantum Hall effect and bosonization of collective fermion states are used as specific examples.
Surface pressure measurements for CFD code validation in hypersonic flow
Oberkampf, W.L.; Aeschliman, D.P.; Henfling, J.F.; Larson, D.E.
1995-07-01T23:59:59.000Z
Extensive surface pressure measurements were obtained on a hypersonic vehicle configuration at Mach 8. All of the experimental results were obtained in the Sandia National Laboratories Mach 8 hypersonic wind tunnel for laminar boundary layer conditions. The basic vehicle configuration is a spherically blunted 10{degrees} half-angle cone with a slice parallel with the axis of the vehicle. The bluntness ratio of the geometry is 10% and the slice begins at 70% of the length of the vehicle. Surface pressure measurements were obtained for angles of attack from {minus}10 to + 18{degrees}, for various roll angles, at 96 locations on the body surface. A new and innovative uncertainty analysis was devised to estimate the contributors to surface pressure measurement uncertainty. Quantitative estimates were computed for the uncertainty contributions due to the complete instrumentation system, nonuniformity of flow in the test section of the wind tunnel, and variations in the wind tunnel model. This extensive set of high-quality surface pressure measurements is recommended for use in the calibration and validation of computational fluid dynamics codes for hypersonic flow conditions.
COMPUTATIONAL FLUID DYNAMICS INCOMPRESSIBLE FLOW
McDonough, James M.
to numerically solve the Euler equations in order to predict effects of bomb blast waves following WW IIÂ71, and was published the following year [1]. Computing power at that time was still grossly inadequate for what we.S., in Europe (especially France, Great Britain and Sweden) and in the (former) Soviet Union. Today
Geophysical Fluid Dynamics Laboratory Review
ice from continent out to open ocean to melt Avoids coldfresh bias around Antarctica (led to excess seaice) · Lagrangian model of icebergs · Exporting fresh cap beyond shelf edge increases is most useful for ocean climate? Some issues affecting zcoords also affect hybrid coords if coordinate
Anastasia Gribik; Doona Guillen, PhD; Daniel Ginosar, PhD
2008-09-01T23:59:59.000Z
Currently multi-tubular fixed bed reactors, fluidized bed reactors, and slurry bubble column reactors (SBCRs) are used in commercial Fischer Tropsch (FT) synthesis. There are a number of advantages of the SBCR compared to fixed and fluidized bed reactors. The main advantage of the SBCR is that temperature control and heat recovery are more easily achieved. The SBCR is a multiphase chemical reactor where a synthesis gas, comprised mainly of H2 and CO, is bubbled through a liquid hydrocarbon wax containing solid catalyst particles to produce specialty chemicals, lubricants, or fuels. The FT synthesis reaction is the polymerization of methylene groups [-(CH2)-] forming mainly linear alkanes and alkenes, ranging from methane to high molecular weight waxes. The Idaho National Laboratory is developing a computational multiphase fluid dynamics (CMFD) model of the FT process in a SBCR. This paper discusses the incorporation of absorption and reaction kinetics into the current hydrodynamic model. A phased approach for incorporation of the reaction kinetics into a CMFD model is presented here. Initially, a simple kinetic model is coupled to the hydrodynamic model, with increasing levels of complexity added in stages. The first phase of the model includes incorporation of the absorption of gas species from both large and small bubbles into the bulk liquid phase. The driving force for the gas across the gas liquid interface into the bulk liquid is dependent upon the interfacial gas concentration in both small and large bubbles. However, because it is difficult to measure the concentration at the gas-liquid interface, coefficients for convective mass transfer have been developed for the overall driving force between the bulk concentrations in the gas and liquid phases. It is assumed that there are no temperature effects from mass transfer of the gas phases to the bulk liquid phase, since there are only small amounts of dissolved gas in the liquid phase. The product from the incorporation of absorption is the steady state concentration profile of the absorbed gas species in the bulk liquid phase. The second phase of the model incorporates a simplified macrokinetic model to the mass balance equation in the CMFD code. Initially, the model assumes that the catalyst particles are sufficiently small such that external and internal mass and heat transfer are not rate limiting. The model is developed utilizing the macrokinetic rate expression developed by Yates and Satterfield (1991). Initially, the model assumes that the only species formed other than water in the FT reaction is C27H56. Change in moles of the reacting species and the resulting temperature of the catalyst and fluid phases is solved simultaneously. The macrokinetic model is solved in conjunction with the species transport equations in a separate module which is incorporated into the CMFD code.
Optimal dimensionless design and analysis of jet ejectors as compressors and thrust augmenters
Mohan, Ganesh
2006-08-16T23:59:59.000Z
and mesh generation) and FLUENT (Computational Fluid Dynamics (CFD) solver kit). Scripting languages PYTHON and SCHEME were used to automate this process. The CFD model employed 2D axis symmetric, steady-state flow using the ??k method (including wall...
Relativistic viscoelastic fluid mechanics
Masafumi Fukuma; Yuho Sakatani
2011-09-01T23:59:59.000Z
A detailed study is carried out for the relativistic theory of viscoelasticity which was recently constructed on the basis of Onsager's linear nonequilibrium thermodynamics. After rederiving the theory using a local argument with the entropy current, we show that this theory universally reduces to the standard relativistic Navier-Stokes fluid mechanics in the long time limit. Since effects of elasticity are taken into account, the dynamics at short time scales is modified from that given by the Navier-Stokes equations, so that acausal problems intrinsic to relativistic Navier-Stokes fluids are significantly remedied. We in particular show that the wave equations for the propagation of disturbance around a hydrostatic equilibrium in Minkowski spacetime become symmetric hyperbolic for some range of parameters, so that the model is free of acausality problems. This observation suggests that the relativistic viscoelastic model with such parameters can be regarded as a causal completion of relativistic Navier-Stokes fluid mechanics. By adjusting parameters to various values, this theory can treat a wide variety of materials including elastic materials, Maxwell materials, Kelvin-Voigt materials, and (a nonlinearly generalized version of) simplified Israel-Stewart fluids, and thus we expect the theory to be the most universal description of single-component relativistic continuum materials. We also show that the presence of strains and the corresponding change in temperature are naturally unified through the Tolman law in a generally covariant description of continuum mechanics.
R. Caimmi
2007-10-20T23:59:59.000Z
A theory of collisionless fluids is developed in a unified picture, where nonrotating figures with anisotropic random velocity component distributions and rotating figures with isotropic random velocity component distributions, make adjoints configurations to the same system. R fluids are defined and mean and rms angular velocities and mean and rms tangential velocity components are expressed, by weighting on the moment of inertia and the mass, respectively. The definition of figure rotation is extended to R fluids. The generalized tensor virial equations are formulated for R fluids and further attention is devoted to axisymmetric configurations where, for selected coordinate axes, a variation in figure rotation has to be counterbalanced by a variation in anisotropy excess and vice versa. A microscopical analysis of systematic and random motions is performed under a few general hypotheses, by reversing the sign of tangential or axial velocity components of an assigned fraction of particles, leaving the distribution function and other parameters unchanged (Meza 2002). The application of the reversion process to tangential velocity components, implies the conversion of random motion rotation kinetic energy into systematic motion rotation kinetic energy. The application of the reversion process to axial velocity components, implies the conversion of random motion translation kinetic energy into systematic motion translation kinetic energy, and the loss related to a change of reference frame is expressed in terms of systematic (imaginary) motion rotation kinetic energy. A procedure is sketched for deriving the spin parameter distribution (including imaginary rotation) from a sample of observed or simulated large-scale collisionless fluids i.e. galaxies and galaxy clusters.
Comparative Analysis of CFD ?P vs. Measured ?P for Compressed Flexible Ducts
Ugursal, A.; Culp, C.H.
Reproduced with permission of the copyright owner. Further reproduction prohibited without permission. Comparative Analysis of CFD [Delta]P vs. Measured [Delta]P for Compressed Flexible Ducts Ugursal, Ahmet;Culp, Charles ASHRAE Transactions; 2007...
CFD based rotordynamic coefficients for labyrinth seals and impeller leakage paths
Bhattacharya, Avijit
1997-01-01T23:59:59.000Z
accurately using simple flow model like bulk flow. CFD approach is employed since it can accurately predict and capture recirculating zones using proper mesh distribution. The Impeller Leakage paths and Labyrinth Seals, typically, have a recirculation zone...
Deng, T.; Zhang, Q.; Zhang, G.; Yuan, H.
2006-01-01T23:59:59.000Z
The Hunan International Exhibition Center (HIEC) is a large space building. A stratified air-conditioning system on the second floor of the building has been adopted. Due to some problems with the air supply jet diffuser, CFD simulations were...
A Multi-Model Approach for Uncertainty Propagation and Model Calibration in CFD Applications
Wang, Jian-xun; Xiao, Heng
2015-01-01T23:59:59.000Z
Proper quantification and propagation of uncertainties in computational simulations are of critical importance. This issue is especially challenging for CFD applications. A particular obstacle for uncertainty quantifications in CFD problems is the large model discrepancies associated with the CFD models used for uncertainty propagation. Neglecting or improperly representing the model discrepancies leads to inaccurate and distorted uncertainty distribution for the Quantities of Interest. High-fidelity models, being accurate yet expensive, can accommodate only a small ensemble of simulations and thus lead to large interpolation errors and/or sampling errors; low-fidelity models can propagate a large ensemble, but can introduce large modeling errors. In this work, we propose a multi-model strategy to account for the influences of model discrepancies in uncertainty propagation and to reduce their impact on the predictions. Specifically, we take advantage of CFD models of multiple fidelities to estimate the model ...
General Purpose Steam Table Library: CASL L3:THM.CFD.P7.04 Milestone...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
General Purpose Steam Table Library: CASL L3:THM.CFD.P7.04 Milestone Report John H. Carpenter, Noel Belcourt, Robert Nourgalieu SNLINL Completed: August 30, 2013 CASL-...
Comparative Study: CFD ?P Versus Measured ?P for 30% Flexible Ducts
Ugursal, A.; Culp, C.
2006-01-01T23:59:59.000Z
very close comparison with measured results. Flexible ducts can be installed in a variety of configurations with different compression. A configuration was specified for this study which focused on 30% compressed 5 foot-long flexible duct and 2... foot-long circular ducts placed on both ends. A CFD model was built and simulations were run under different volumetric air flows. The static pressure drop for those conditions were analyzed and displayed. The final CFD model is tuned until...
Wai, Chien M. (Moscow, ID); Laintz, Kenneth E. (Los Alamos, NM)
1999-01-01T23:59:59.000Z
A method of extracting metalloid and metal species from a solid or liquid material by exposing the material to a supercritical fluid solvent containing a chelating agent is described. The chelating agent forms chelates that are soluble in the supercritical fluid to allow removal of the species from the material. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent is a fluorinated .beta.-diketone. In especially preferred embodiments the extraction solvent is supercritical carbon dioxide, and the chelating agent comprises a fluorinated .beta.-diketone and a trialkyl phosphate, or a fluorinated .beta.-diketone and a trialkylphosphine oxide. Although a trialkyl phosphate can extract lanthanides and actinides from acidic solutions, a binary mixture comprising a fluorinated .beta.-diketone and a trialkyl phosphate or a trialkylphosphine oxide tends to enhance the extraction efficiencies for actinides and lanthanides. The method provides an environmentally benign process for removing contaminants from industrial waste without using acids or biologically harmful solvents. The method is particularly useful for extracting actinides and lanthanides from acidic solutions. The chelate and supercritical fluid can be regenerated, and the contaminant species recovered, to provide an economic, efficient process.
E-Print Network 3.0 - artery aneurysm causing Sample Search Results
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model was constructed... "Validation and application of Computational Fluid Dynamics (CFD) to ... Source: Lennard, William N. - Department of Physics and Astronomy, University...
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Artery by Proper Orthogonal Decomposition Summary: employ computational fluid dynamics (CFD) to investigate blood flow in a carotid artery, which has... to turbulence is expected...
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the stenosis increased in severity. Since the early 1970's, computational fluid dynamics (CFD... . These deficiencies exist for both the arterial wall and for the atherosclerotic...
Mobile Ice Nucleus Spectrometer
Kulkarni, Gourihar R.; Kok, G. L.
2012-05-07T23:59:59.000Z
This first year report presents results from a computational fluid dynamics (CFD) study to assess the flow and temperature profiles within the mobile ice nucleus spectrometer.
) thermography experiments, computational fluid dynamics (CFD) simulations, and calculations with traditional software for simulating two-dimensional heat conduction were conducted.The IR thermography
Modelling microscale fuel cells.
Bazylak, Aimy Ming Jii
2009-01-01T23:59:59.000Z
??The focus of this work is to investigate transport phenomena in recently developed microscale fuel cell designs using computational fluid dynamics (CFD). Two microscale fuel… (more)
Modeling and simulation for a PEM fuel cell with catalyst layers in finite thickness.
Yin, Jianghui (Author)
2007-01-01T23:59:59.000Z
??A detailed non-isothermal computational fluid dynamics (CFD) model for proton electrolyte membrane (PEM) fuel cells is developed in this thesis. This model consists of the… (more)
E-Print Network 3.0 - artery spatial distribution Sample Search...
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Engineering, Duke University Collection: Biology and Medicine 5 Abstract Computed tomography (CT) slices are combined with computational fluid dynamics (CFD) to Summary:...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
and air flows as well as ignition, combustion, and pollutant-formation processes in engines. July 26, 2013 software The KIVA family of Computational Fluid Dynamics (CFD)...
E-Print Network 3.0 - atherosclerotic human coronary Sample Search...
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for: atherosclerotic human coronary Page: << < 1 2 3 4 5 > >> 1 Abstract Computed tomography (CT) slices are combined with computational fluid dynamics (CFD) to Summary: ) to...
E-Print Network 3.0 - atherosclerotic proximal coronary Sample...
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for: atherosclerotic proximal coronary Page: << < 1 2 3 4 5 > >> 1 Abstract Computed tomography (CT) slices are combined with computational fluid dynamics (CFD) to Summary: ) to...
Spinning Fluids: A Group Theoretical Approach
Dario Capasso; Debajyoti Sarkar
2014-04-07T23:59:59.000Z
We extend the Lagrangian formulation of relativistic non-abelian fluids in group theory language. We propose a Mathisson-Papapetrou equation for spinning fluids in terms of the reduction limit of de Sitter group. The equation we find correctly boils down to the one for non-spinning fluids. We study the application of our results for an FRW cosmological background for fluids with no vorticity and for dusts in the vicinity of a Kerr black hole. We also explore two alternative approaches based on a group theoretical formulation of particles dynamics.
BEE 331. Bio-Fluid Mechanics Fall Semester 2005
Walter, M.Todd
BEE 331. Bio-Fluid Mechanics Fall Semester 2005 1. Course Outcomes: Outcome 1. Learn the principles of fluid hydrostatics and dynamics in biological systems. Assessment Metrics: Home work assignments 1, 2. Become familiar with methods of measuring fluid flow. Assessment Metrics: Homework assignments: 2
Euler's fluid equations: Optimal Control vs Optimization
Darryl D. Holm
2009-09-28T23:59:59.000Z
An optimization method used in image-processing (metamorphosis) is found to imply Euler's equations for incompressible flow of an inviscid fluid, without requiring that the Lagrangian particle labels exactly follow the flow lines of the Eulerian velocity vector field. Thus, an optimal control problem and an optimization problem for incompressible ideal fluid flow both yield the \\emph {same} Euler fluid equations, although their Lagrangian parcel dynamics are \\emph{different}. This is a result of the \\emph{gauge freedom} in the definition of the fluid pressure for an incompressible flow, in combination with the symmetry of fluid dynamics under relabeling of their Lagrangian coordinates. Similar ideas are also illustrated for SO(N) rigid body motion.
Carlisle, Bruce Scott
2012-06-07T23:59:59.000Z
Though both film and video radiographic image techniques are available in neutron radiography, radiographic cameras are commonly used to capture the dynamic flow patterns in a rapid sequence of images. These images may be useful to verify two...
Fellman, Batya A. (Batya Ayala)
2008-01-01T23:59:59.000Z
Biological cells and organisms employ a different method of propulsion when in viscous, viscolelastic fluids rather than Newtonian fluids. By studying the dynamics of a flag under a flow of a viscoelastic fluid, we hope ...
Viscosity of a nucleonic fluid
Aram Z. Mekjian
2012-03-21T23:59:59.000Z
The viscosity of nucleonic matter is studied both classically and in a quantum mechanical description. The collisions between particles are modeled as hard sphere scattering as a baseline for comparison and as scattering from an attractive square well potential. Properties associated with the unitary limit are developed which are shown to be approximately realized for a system of neutrons. The issue of near perfect fluid behavior of neutron matter is remarked on. Using some results from hard sphere molecular dynamics studies near perfect fluid behavior is discussed further.
.S./M.S. in Mechanical Engineering, Aerospace Sciences & Engineering, Computer sciences, or Applied mathematics: Â· Knowledge of computational fluid dynamics and programming experience in C++ and Fortran Â· Experience
Eça, L. [Instituto Superior Técnico, Department of Mechanical Engineering, Av. Rovisco Pais, 1049-001 Lisbon (Portugal); Hoekstra, M. [Maritime Research Institute Netherlands, PO Box 28 6700 AA, Wageningen (Netherlands)
2014-04-01T23:59:59.000Z
This paper offers a procedure for the estimation of the numerical uncertainty of any integral or local flow quantity as a result of a fluid flow computation; the procedure requires solutions on systematically refined grids. The error is estimated with power series expansions as a function of the typical cell size. These expansions, of which four types are used, are fitted to the data in the least-squares sense. The selection of the best error estimate is based on the standard deviation of the fits. The error estimate is converted into an uncertainty with a safety factor that depends on the observed order of grid convergence and on the standard deviation of the fit. For well-behaved data sets, i.e. monotonic convergence with the expected observed order of grid convergence and no scatter in the data, the method reduces to the well known Grid Convergence Index. Examples of application of the procedure are included. - Highlights: • Estimation of the numerical uncertainty of any integral or local flow quantity. • Least squares fits to power series expansions to handle noisy data. • Excellent results obtained for manufactured solutions. • Consistent results obtained for practical CFD calculations. • Reduces to the well known Grid Convergence Index for well-behaved data sets.
Jake P. Gentle; Kurt S Myers; Tyler B Phillips; Inanc Senocak; Phil Anderson
2014-08-01T23:59:59.000Z
Dynamic Line Rating (DLR) is a smart grid technology that allows the rating of power line to be based on real-time conductor temperature dependent on local weather conditions. In current practice overhead power lines are generally given a conservative rating based on worst case weather conditions. Using historical weather data collected over a test bed area, we demonstrate there is often additional transmission capacity not being utilized with the current static rating practice. We investigate a new dynamic line rating methodology using computational fluid dynamics (CFD) to determine wind conditions along transmission lines at dense intervals. Simulated results are used to determine conductor temperature by calculating the transient thermal response of the conductor under variable environmental conditions. In calculating the conductor temperature, we use both a calculation with steady-state assumption and a transient calculation. Under low wind conditions, steady-state assumption predicts higher conductor temperatures that could lead to curtailments, whereas transient calculations produce conductor temperatures that are significantly lower, implying the availability of additional transmission capacity.
Chen, Qingyan "Yan"
for the correct prediction of the convective heat. A finer grid resolution in CFD does not always lead to a more conservation equations of flow on these grid cells. As shown in Figure 1(a), CFD calculates convective heat1 NUMERICAL DETERMINATION AND TREATMENT OF CONVECTIVE HEAT TRANSFER COEFFICIENT IN THE COUPLED
Frey, Pascal
CFD simulations of enhanced condensational growth (ECG) applied to respiratory drug delivery t Enhanced condensational growth (ECG) is a newly proposed concept for respiratory drug delivery in which and evaluate a CFD model of ECG in a simple tubular geometry with direct comparisons to in vitro results
INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS Int. J. Numer. Meth. Fluids (2012)
Frey, Pascal
are still within reasonable range. Nevertheless, for test case two, which has higher density and viscosity, emulsification, spraying and so on. The kinematics and dynamics of the fluid interfaces play an important role
Branching patterns emerge in a mathematical model of the dynamics of lung development
2014-01-01T23:59:59.000Z
fluid pressure and fluid–mechanical interactions. Lubarsky &The absence of fluid or mechanical effects may also ex-model to the mechanical and fluid dynamical factors in lung
Dilley, Lorie
2013-01-01T23:59:59.000Z
Fluid inclusion gas analysis for wells in various geothermal areas. Analyses used in developing fluid inclusion stratigraphy for wells and defining fluids across the geothermal fields. Each sample has mass spectrum counts for 180 chemical species.
DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]
Dilley, Lorie
Fluid inclusion gas analysis for wells in various geothermal areas. Analyses used in developing fluid inclusion stratigraphy for wells and defining fluids across the geothermal fields. Each sample has mass spectrum counts for 180 chemical species.
Chemically Reactive Working Fluids
Broader source: Energy.gov (indexed) [DOE]
commercial application. Goal: Demonstrate feasibility of employing chemically reacting fluids (CRFW) as heat transfer fluids (HTF) for CSP systems operating at 650C-1200C....
Simulating Fluids Exhibiting Microstructure
... fluids containing elastic particles, and polymer fluids, all exhibit non-trivial macroscopic behavior due to interactions occurring on micro/mesoscopic scales.
Friction-Induced Fluid Heating in Nanoscale Helium Flows
Li Zhigang [Department of Mechanical Engineering, Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong)
2010-05-21T23:59:59.000Z
We investigate the mechanism of friction-induced fluid heating in nanoconfinements. Molecular dynamics simulations are used to study the temperature variations of liquid helium in nanoscale Poiseuille flows. It is found that the fluid heating is dominated by different sources of friction as the external driving force is changed. For small external force, the fluid heating is mainly caused by the internal viscous friction in the fluid. When the external force is large and causes fluid slip at the surfaces of channel walls, the friction at the fluid-solid interface dominates over the internal friction in the fluid and is the major contribution to fluid heating. An asymmetric temperature gradient in the fluid is developed in the case of nonidentical walls and the general temperature gradient may change sign as the dominant heating factor changes from internal to interfacial friction with increasing external force.
Biologically-Inspired Adaptive Pectoral-Like Fin Control System For CFD Parameterized AUV
Mittal, Rajat
on the normalized gradient scheme. In the closed-loop system, time-varying yaw an- gle reference trajectoriesBiologically-Inspired Adaptive Pectoral-Like Fin Control System For CFD Parameterized AUV Mugdha S fin control, Adaptive control, Yaw plane control. Abstract- This paper treats the question of adaptive
Solution characters of iterative coupling between energy simulation and CFD programs
Chen, Qingyan "Yan"
third of the primary energy consumption and two thirds of the electricity. Designing an energy/heating loads, coil loads, and energy consumption can be obtained on an hourly or sub-hourly basis for a period1 Solution characters of iterative coupling between energy simulation and CFD programs Zhiqiang
Unsteady, high Reynolds number validation cases for a multi-phase CFD analysis tool have been
Kunz, Robert Francis
and constituent volume fraction transport/generation for liquid, condensable vapor and non-condensable gas fields1 Abstract Unsteady, high Reynolds number validation cases for a multi-phase CFD analysis tool have of the effect of cavitation number, Reynolds number and turbulence model has been made. Analysis of the modeled
1 Copyright 1999 by ASME MULTI-PHASE CFD ANALYSIS OF NATURAL AND VENTILATED CAVITATION
Kunz, Robert Francis
volume fraction transport/generation for liquid, condensable vapor and non-con- densable gas fields between condensable vapor and non-condensable gas, a requirement of our current applica- tion. By solving1 Copyright Â© 1999 by ASME MULTI-PHASE CFD ANALYSIS OF NATURAL AND VENTILATED CAVITATION ABOUT
Volume 0 (1981), Number 0 pp. 1000 Practical CFD Simulations on Programmable Graphics
Utah, University of
Volume 0 (1981), Number 0 pp. 1Â000 Practical CFD Simulations on Programmable Graphics Hardware-based graphics APIs changed the panorama of consumer-level graphics: today, GPUs are cheap, fast and ubiquitous of boundary conditions and incorporates energy trans- port through the traditional Boussinesq approximation
CFD Analysis of Nuclear Fuel Bundles and Spacer Grids for PWR Reactors
Capone, Luigi
2012-10-19T23:59:59.000Z
4.3 The Numerical Approach ......................................................... 95 viii 4.4 Implementation in CFD Codes ................................................. 99 4... Total standard error refinement 3 ................................................................... 56 xii Figure 62 Experimental results plane B1 axial velocity (a), KER 138M mesh constant inlet (b), SST138M mesh periodic inlet (c...
Assessment of Transition Model and CFD Methodology for Wind Turbine Flows
Alonso, Juan J.
as fossil fuels are replaced by renewable alternatives. In the U.S., the Department of Energy has publishedAssessment of Transition Model and CFD Methodology for Wind Turbine Flows Aniket C. Aranake Vinod K Navier Stokes (RANS) solver with a transition model is performed for wind turbine applications
Numerical Analysis of Winglets on Wind Turbine Blades using CFD Jeppe Johansen
Numerical Analysis of Winglets on Wind Turbine Blades using CFD Jeppe Johansen and Niels N of adding a winglet to a wind turbine rotor is to decrease the total drag from the blades and thereby increase. The resulting pressure difference on an operating wind turbine blade causes inward spanwise flow
Performance of Coupled Building Energy and CFD Simulations Zhiqiang (John) Zhai
Chen, Qingyan "Yan"
and CFD. This investigation implemented these concepts and developed an integrated building design tool, E, West Lafayette, IN 47907-2088, USA Abstract The integration of building energy simulation (ES of the integrated building simulation over the separated energy simulation and computational
Conformal higher-order viscoelastic fluid mechanics
Masafumi Fukuma; Yuho Sakatani
2012-05-28T23:59:59.000Z
We present a generally covariant formulation of conformal higher-order viscoelastic fluid mechanics with strain allowed to take arbitrarily large values. We give a general prescription to determine the dynamics of a relativistic viscoelastic fluid in a way consistent with the hypothesis of local thermodynamic equilibrium and the second law of thermodynamics. We then elaborately study the transient time scales at which the strain almost relaxes and becomes proportional to the gradients of velocity. We particularly show that a conformal second-order fluid with all possible parameters in the constitutive equations can be obtained without breaking the hypothesis of local thermodynamic equilibrium, if the conformal fluid is defined as the long time limit of a conformal second-order viscoelastic system. We also discuss how local thermodynamic equilibrium could be understood in the context of the fluid/gravity correspondence.
DeRoos, B.G.; Downing, J.P. Jr.; Neal, M.P.
1995-11-14T23:59:59.000Z
An improved fluid container for the transport, collection, and dispensing of a sample fluid that maintains the fluid integrity relative to the conditions of the location at which it is taken. More specifically, the invention is a fluid sample transport container that utilizes a fitting for both penetrating and sealing a storage container under controlled conditions. Additionally, the invention allows for the periodic withdrawal of portions of the sample fluid without contamination or intermixing from the environment surrounding the sample container. 13 figs.
On the Hamiltonian Description of Fluid Mechanics
I. Antoniou; G. P. Pronko
2002-03-14T23:59:59.000Z
We suggest the Hamiltonian approach for fluid mechanics based on the dynamics, formulated in terms of Lagrangian variables. The construction of the canonical variables of the fluid sheds a light of the origin of Clebsh variables, introduced in the previous century. The developed formalism permits to relate the circulation conservation (Tompson theorem) with the invariance of the theory with respect to special diffiomorphisms and establish also the new conservation laws. We discuss also the difference of the Eulerian and Lagrangian description, pointing out the incompleteness of the first. The constructed formalism is also applicable for ideal plasma. We conclude with several remarks on the quantization of the fluid.
The use of dynamic adaptive chemistry in combustion simulation of gasoline surrogate fuels
Liang, Long; Raman, Sumathy; Farrell, John T. [Corporate Strategic Research Laboratories, ExxonMobil Research and Engineering Company, 1545 Route 22 East, Annandale, NJ 08801 (United States); Stevens, John G. [Corporate Strategic Research Laboratories, ExxonMobil Research and Engineering Company, 1545 Route 22 East, Annandale, NJ 08801 (United States); Department of Mathematical Sciences, Montclair State University, Montclair, NJ 07043 (United States)
2009-07-15T23:59:59.000Z
A computationally efficient dynamic adaptive chemistry (DAC) scheme is described that permits on-the-fly mechanism reduction during reactive flow calculations. The scheme reduces a globally valid full mechanism to a locally, instantaneously applicable smaller mechanism. Previously we demonstrated its applicability to homogeneous charge compression ignition (HCCI) problems with n-heptane [L. Liang, J.G. Stevens, J.T. Farrell, Proc. Combust. Inst. 32 (2009) 527-534]. In this work we demonstrate the broader utility of the DAC scheme through the simulation of HCCI and shock tube ignition delay times (IDT) for three gasoline surrogates, including two- and three-component blends of primary reference fuels (PRF) and toluene reference fuels (TRF). Both a detailed 1099-species mechanism and a skeletal 150-species mechanism are investigated as the full mechanism to explore the impact of fuel complexity on the DAC scheme. For all conditions studied, pressure and key species profiles calculated using the DAC scheme are in excellent agreement with the results obtained using the full mechanisms. For the HCCI calculations using the 1099- and 150-species mechanisms, the DAC scheme achieves 70- and 15-fold CPU time reductions, respectively. For the IDT problems, corresponding speed-up factors of 10 and two are obtained. Practical guidance is provided for choosing the search-initiating species set, selecting the threshold, and implementing the DAC scheme in a computational fluid dynamics (CFD) framework. (author)
Control of underactuated fluid-body systems with real-time particle image velocimetry
Roberts, John W., Ph. D. Massachusetts Institute of Technology
2012-01-01T23:59:59.000Z
Controlling the interaction of a robot with a fluid, particularly when the desired behavior is intimately related to the dynamics of the fluid, is a difficult and important problem. High-performance aircraft cannot ignore ...
A numerical framework for the direct simulation of solid-fluid systems
Cook, Benjamin Koger, 1965-
2001-01-01T23:59:59.000Z
Our understanding of solid-fluid dynamics has been severely limited by the nonexistence of a high-fidelity modeling capability for these multiphase systems. Continuum modeling approaches overlook the microscale solid-fluid ...
Standardization of Thermo-Fluid Modeling in Modelica.Fluid
Franke, Rudiger
2010-01-01T23:59:59.000Z
Thermo-Fluid Systems, Modelica 2003 Conference, Linköping,H. Tummescheit: The Modelica Fluid and Media Library forThermo-Fluid Pipe Networks, Modelica 2006 Conference, Vi-
Engineering Fluid Dynamics Research of the Group Engineering Fluid
Twente, Universiteit
are conducted. Thin-film flows The flow in narrow domains under extreme conditions between deforming surfaces is studied theoretically and experimentally. A typical example is the lubricant film in roller bearings (Elasto- Hydrodynamic Lubrication). The theoretical research involves modelling, development of efficient
Graduate Studies Environmental Fluid Mechanics
Storici, Francesca
Graduate Studies Environmental Fluid Mechanics and Water Resources Engineering GRADUATE COURSESResourcesManagement Â· IntermediateFluidMechanics Â· AdvancedFluidMechanics Â· EnvironmentalFluidMechanics Â· AdvancedEnvironmental FluidMechanics Â· FluidMechanicsofOrganisms Â· OpenChannelHydraulics Â· SedimentTransport Â· ComputationalFluidMechanics
Environmentally safe fluid extractor
Sungaila, Zenon F. (Orland Park, IL)
1993-01-01T23:59:59.000Z
An environmentally safe fluid extraction device for use in mobile laboratory and industrial settings comprising a pump, compressor, valving system, waste recovery tank, fluid tank, and a exhaust filtering system.
Johnston, Roger G. (Los Alamos, NM); Garcia, Anthony R. E. (Espanola, NM); Martinez, Ronald K. (Santa Cruz, NM)
2001-09-25T23:59:59.000Z
The invention includes a rotatable tool for collecting fluid through the wall of a container. The tool includes a fluid collection section with a cylindrical shank having an end portion for drilling a hole in the container wall when the tool is rotated, and a threaded portion for tapping the hole in the container wall. A passageway in the shank in communication with at least one radial inlet hole in the drilling end and an opening at the end of the shank is adapted to receive fluid from the container. The tool also includes a cylindrical chamber affixed to the end of the shank opposite to the drilling portion thereof for receiving and storing fluid passing through the passageway. The tool also includes a flexible, deformable gasket that provides a fluid-tight chamber to confine kerf generated during the drilling and tapping of the hole. The invention also includes a fluid extractor section for extracting fluid samples from the fluid collecting section.
Lenert, Andrej
2012-01-01T23:59:59.000Z
The choice of heat transfer fluids has significant effects on the performance, cost, and reliability of solar thermal systems. In this chapter, we evaluate existing heat transfer fluids such as oils and molten salts based ...
Methods for fluid separations, and devices capable of separating fluids
TeGrotenhuis, Ward E [Kennewick, WA; Stenkamp, Victoria S [Richland, WA
2006-05-30T23:59:59.000Z
Wick-Containing apparatus capable of separating fluids and methods of separating fluids using wicks are disclosed.
Methods for fluid separations, and devices capable of separating fluids
TeGrotenhuis, Ward E. (Kennewick, WA); Stenkamp, Victoria S. (Richland, WA)
2007-09-25T23:59:59.000Z
Wick-Containing apparatus capable of separating fluids and methods of separating fluids using wicks are disclosed.
Entropy production at freeze-out from dissipative fluids
E. Molnar
2007-09-17T23:59:59.000Z
Entropy production due to shear viscosity during the continuous freeze-out of a longitudinally expanding dissipative fluid is addressed. Assuming the validity of the fluid dynamical description during the continuous removal of interacting matter we estimated a small entropy production as function of the freeze-out duration and the ratio of dissipative to non-dissipative quantities in case of a relativistic massless pion fluid.
Graduate Studies Environmental Fluid Mechanics
Jacobs, Laurence J.
Graduate Studies Environmental Fluid Mechanics and Water Resources Engineering ENVIRONMENTAL FLUID MECHANICS AND WATER RESOURCES ENGINEERING (EFMWR) The environmental fluid mechanics and water resources Environmental Fluid Mechanics and Hydraulic Engineering research focuses on turbulent entrainment, transport
Carbon-bearing fluids at nanoscale interfaces
Cole, David [Ohio State University; Ok, Salim [Ohio State University, Columbus; Phan, A [Ohio State University, Columbus; Rother, Gernot [ORNL; Striolo, Alberto [Oklahoma University; Vlcek, Lukas [ORNL
2013-01-01T23:59:59.000Z
The behaviour of fluids at mineral surfaces or in confined geometries (pores, fractures) typically differs from their bulk behaviour in many ways due to the effects of large internal surfaces and geometrical confinement. We summarize research performed on C-O-H fluids at nanoscale interfaces in materials of interest to the earth and material sciences (e.g., silica, alumina, zeolites, clays, rocks, etc.), emphasizing those techniques that assess microstructural modification and/or dynamical behaviour such as gravimetric analysis, small-angle (SANS) neutron scattering, and nuclear magnetic resonance (NMR). Molecular dynamics (MD) simulations will be described that provide atomistic characterization of interfacial and confined fluid behaviour as well as aid in the interpretation of the neutron scattering results.
2.25 Advanced Fluid Mechanics, Fall 2002
Sonin, A. A.
Survey of principal concepts and methods of fluid dynamics. Mass conservation, momentum, and energy equations for continua. Navier-Stokes equation for viscous flows. Similarity and dimensional analysis. Lubrication theory. ...
Miller, Jan D; Hupka, Jan; Aranowski, Robert
2012-11-20T23:59:59.000Z
A spinning fluids reactor, includes a reactor body (24) having a circular cross-section and a fluid contactor screen (26) within the reactor body (24). The fluid contactor screen (26) having a plurality of apertures and a circular cross-section concentric with the reactor body (24) for a length thus forming an inner volume (28) bound by the fluid contactor screen (26) and an outer volume (30) bound by the reactor body (24) and the fluid contactor screen (26). A primary inlet (20) can be operatively connected to the reactor body (24) and can be configured to produce flow-through first spinning flow of a first fluid within the inner volume (28). A secondary inlet (22) can similarly be operatively connected to the reactor body (24) and can be configured to produce a second flow of a second fluid within the outer volume (30) which is optionally spinning.
Broader source: Energy.gov [DOE]
Presentation given by Argonne National Laboratory at 2014 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Office Annual Merit Review and Peer Evaluation Meeting about CFD simulations...
Membrane fluids and Dirac membrane fluids
M. G. Ivanov
2005-05-04T23:59:59.000Z
There are two different methods to describe membrane (string) fluids, which use different field content. The relation between the methods is clarified by construction of combined method. Dirac membrane field appears naturally in new approach. It provides a possibility to consider new aspects of electrodynamics-type theories with electric and magnetic sources. The membrane fluid models automatically prohibit simulatenos existence of electric and magnetic currents. Possible applications to the dark energy problem are mentioned.
Math 513 -Mathematical Principles of Fluid Mechanics -Fall 2013 Tu , Th 11:1012:25 in Ayres 112,
Schulze, Tim
Math 513 - Mathematical Principles of Fluid Mechanics - Fall 2013 Tu , Th 11:10Â12:25 in Ayres 112: Â· A Mathematical Introduction to Fluid Mechanics by A. J. Chorin & J. E. Marsden. Â· An Introduction to Fluid Dynamics by G.K. Batchelor. Â· Fluid Mechanics: Volume 6 (Course of Theoretical Physics) by L.D. Landau & E
Angel, S.M.
1987-02-27T23:59:59.000Z
Particular gases or liquids are detected with a fiber optic element having a cladding or coating of a material which absorbs the fluid or fluids and which exhibits a change of an optical property, such as index of refraction, light transmissiveness or fluoresence emission, for example, in response to absorption of the fluid. The fluid is sensed by directing light into the fiber optic element and detecting changes in the light, such as exit angle changes for example, that result from the changed optical property of the coating material. The fluid detector may be used for such purposes as sensing toxic or explosive gases in the atmosphere, measuring ground water contamination or monitoring fluid flows in industrial processes, among other uses. 10 figs.
Bryson, W.R.
1983-06-01T23:59:59.000Z
Prior to 1974 the disposal of drilling fluids was not considered to be much of an environmental problem. In the past, disposal of drilling fluids was accomplished in various ways such as spreading on oil field lease roads to stabilize the road surface and control dust, spreading in the base of depressions of sandy land areas to increase water retention, and leaving the fluid in the reserve pit to be covered on closure of the pit. In recent years, some states have become concerned over the indescriminate dumping of drilling fluids into pits or unauthorized locations and have developed specific regulations to alleviate the perceived deterioration of environmental and groundwater quality from uncontrolled disposal practices. The disposal of drilling fluids in Kansas is discussed along with a newer method or treatment in drilling fluid disposal.
Metalworking and machining fluids
Erdemir, Ali (Naperville, IL); Sykora, Frank (Caledon, ON, CA); Dorbeck, Mark (Brighton, MI)
2010-10-12T23:59:59.000Z
Improved boron-based metal working and machining fluids. Boric acid and boron-based additives that, when mixed with certain carrier fluids, such as water, cellulose and/or cellulose derivatives, polyhydric alcohol, polyalkylene glycol, polyvinyl alcohol, starch, dextrin, in solid and/or solvated forms result in improved metalworking and machining of metallic work pieces. Fluids manufactured with boric acid or boron-based additives effectively reduce friction, prevent galling and severe wear problems on cutting and forming tools.
Purely radiative perfect fluids
B. Bastiaensen; H. R. Karimian; N. Van den Bergh; L. Wylleman
2007-05-08T23:59:59.000Z
We study `purely radiative' (div E = div H = 0) and geodesic perfect fluids with non-constant pressure and show that the Bianchi class A perfect fluids can be uniquely characterized --modulo the class of purely electric and (pseudo-)spherically symmetric universes-- as those models for which the magnetic and electric part of the Weyl tensor and the shear are simultaneously diagonalizable. For the case of constant pressure the same conclusion holds provided one also assumes that the fluid is irrotational.
Fluid Dynamics IB Dr Natalia Berloff
, say, w = where the dot denotes the time derivative, and likewise in the second tube, where w = 2 2 of the jet problem.) Â§3.4.4 Bubbles and cavities: oscillations and collapse This is another
Morphing quantum mechanics and fluid dynamics
Thomas Curtright; David Fairlie
2003-05-28T23:59:59.000Z
We investigate the effects of given pressure gradients on hydrodynamic flow equations. We obtain results in terms of implicit solutions and also in the framework of an extra-dimensional formalism involving the diffusion/Schrodinger equation.
SUMMER PROGRAM IN GEOPHYSICAL FLUID DYNAMICS
Morrison, Philip J.,
JUNE 20-AUGUST 26, 2011 Norman Lebovitz and Phil Morrison, codirectors #12;ii Preface The theme, Keiji Kimura, Norman Lebovitz (standing) Third row (left to right): Ed Spiegel (standing), Karl Helfrich, Unknown, Stefan LlewellynSmith, Philip Hall, Greg Chini, Jan Feys, Andrew Crosby, John Gibson
Sandia National Laboratories: Computational Fluid Dynamics Simulations
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May JunDatastreamsmmcrcalgovInstrumentsrucLas ConchasPassive SolarEducation Programs:CRFProvide Insight for Rotor Design
MECH 386 INDUSTRIAL FLUID MECHANICS INDUSTRIAL FLUID MECHANICS
MECH 386 Â INDUSTRIAL FLUID MECHANICS 1 INDUSTRIAL FLUID MECHANICS MECH 386 Contact information Dr This course is an introduction to industrial fluid mechanics. According to J. C. R. Hunt (a famous fluid mechanics specialist): "industrial fluid mechanics broadly covers those aspects of the design, manufacture
Khandare, Milind Nandkumar
2012-02-14T23:59:59.000Z
of SFDs can be expensive and time consuming. The current work simulates the flow field inside the dynamically deforming annular gap of a SFD using the commercial computational fluid dynamics (CFD) code Fluent and compares the results to the experimental...
Hessel, R; Foster, D; Aceves, S; Flowers, D; Pitz, B; Dec, J; Sjoberg, M; Babajimopoulos, A
2007-04-23T23:59:59.000Z
Multi-zone CFD simulations with detailed kinetics were used to model engine experiments performed on a diesel engine that was converted for single cylinder, HCCI operation, here using iso-octane as the fuel. The modeling goals were to validate the method (multi-zone combustion modeling) and the reaction mechanism (LLNL 857 species iso-octane), both of which performed very well. The purpose of this paper is to document the validation findings and to set the ground work for further analysis of the results by first looking at CO emissions characteristics with varying equivalence ratio.
Mailhes, Corinne
Integration of CFD tools in aerodynamic design of contra-rotating propellers blades. (2011) In: 3rd CEAS concerns. After a Integration of CFD Tools in Aerodynamic Design of Contra-Rotating Propeller Blades S. BÃ©chet and C. A. Negulescu Airbus Operations S.A.S. - Aerodynamics Department, Toulouse, France V. Chapin
Statistical mechanics of homogeneous partly pinned fluid systems
Vincent Krakoviack
2010-12-05T23:59:59.000Z
The homogeneous partly pinned fluid systems are simple models of a fluid confined in a disordered porous matrix obtained by arresting randomly chosen particles in a one-component bulk fluid or one of the two components of a binary mixture. In this paper, their configurational properties are investigated. It is shown that a peculiar complementarity exists between the mobile and immobile phases, which originates from the fact that the solid is prepared in presence of and in equilibrium with the adsorbed fluid. Simple identities follow, which connect different types of configurational averages, either relative to the fluid-matrix system or to the bulk fluid from which it is prepared. Crucial simplifications result for the computation of important structural quantities, both in computer simulations and in theoretical approaches. Finally, possible applications of the model in the field of dynamics in confinement or in strongly asymmetric mixtures are suggested.
Jakaboski, Juan-Carlos (Albuquerque, NM); Hughs, Chance G. (Albuquerque, NM); Todd, Steven N. (Rio Rancho, NM)
2012-01-10T23:59:59.000Z
A fluid blade disablement (FBD) tool that forms both a focused fluid projectile that resembles a blade, which can provide precision penetration of a barrier wall, and a broad fluid projectile that functions substantially like a hammer, which can produce general disruption of structures behind the barrier wall. Embodiments of the FBD tool comprise a container capable of holding fluid, an explosive assembly which is positioned within the container and which comprises an explosive holder and explosive, and a means for detonating. The container has a concavity on the side adjacent to the exposed surface of the explosive. The position of the concavity relative to the explosive and its construction of materials with thicknesses that facilitate inversion and/or rupture of the concavity wall enable the formation of a sharp and coherent blade of fluid advancing ahead of the detonation gases.
General purpose steam table library : CASL L3:THM.CFD.P7.04 milestone report.
Carpenter, John H.; Belcourt, Noel; Nourgaliev, Robert
2013-08-01T23:59:59.000Z
Completion of the CASL L3 milestone THM.CFD.P7.04 provides a general purpose tabular interpolation library for material properties to support, in particular, standardized models for steam properties. The software consists of three parts, implementations of analytic steam models, a code to generate tables from those models, and an interpolation package to interface the tables to CFD codes such as Hydra-TH. Verification of the standard model is maintained through the entire train of routines. The performance of interpolation package exceeds that of freely available analytic implementation of the steam properties by over an order of magnitude.
A two-fluid model for relativistic heat conduction
López-Monsalvo, César S. [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México (Mexico)
2014-01-14T23:59:59.000Z
Three years ago it was presented in these proceedings the relativistic dynamics of a multi-fluid system together with various applications to a set of topical problems [1]. In this talk, I will start from such dynamics and present a covariant formulation of relativistic thermodynamics which provides us with a causal constitutive equation for the propagation of heat in a relativistic setting.
Thermodynamic Model for Fluid-Fluid Interfacial Areas in Porous...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
(free) and isolated (entrapped) nonwetting fluids. The model is restricted to two-fluid systems in which (1) no significant conversion of mechanical work into heat occurs,...
Thermal Fluid Multiphysics Optimization of Spherical Tokamak
Lumsdaine, Arnold [ORNL; Tipton, Joseph B [ORNL; Peng, Yueng Kay Martin [ORNL
2012-01-01T23:59:59.000Z
An experimental Fusion Nuclear Science Facility (FNSF) is required that will create the environment that simultaneously achieves high energy neutrons and high ion fluence necessary in order to bridge the gaps from ITER to the realization of a fusion nuclear power plant. One concept for achieving this is a high duty cycle spherical torus. This study will focus on thermal modeling of the spherical torus centerpost using computational fluid dynamics to effectively model the thermal transfer of the cooling fluid to the centerpost. The design of the fluid channels is optimized in order to minimize the temperature in the centerpost. Results indicate the feasibility of water cooling for a long-pulse spherical torus FNSF.
A CFD M&S PROCESS FOR FAST REACTOR FUEL ASSEMBLIES
Kurt D. Hamman; Ray A. Berry
2008-09-01T23:59:59.000Z
A CFD modeling and simulation process for large-scale problems using an arbitrary fast reactor fuel assembly design was evaluated. Three dimensional flow distributions of sodium for several fast reactor fuel assembly pin spacing configurations were simulated on high performance computers using commercial CFD software. This research focused on 19-pin fuel assembly “benchmark” geometry, similar in design to the Advanced Burner Test Reactor, where each pin is separated by helical wire-wrap spacers. Several two-equation turbulence models including the k-e and SST (Menter) k-? were evaluated. Considerable effort was taken to resolve the momentum boundary layer, so as to eliminate the need for wall functions and reduce computational uncertainty. High performance computers were required to generate the hybrid meshes needed to predict secondary flows created by the wire-wrap spacers; computational meshes ranging from 65 to 85 million elements were common. A general validation methodology was followed, including mesh refinement and comparison of numerical results with empirical correlations. Predictions for velocity, temperature, and pressure distribution are shown. The uncertainty of numerical models, importance of high fidelity experimental data, and the challenges associated with simulating and validating large production-type problems are presented.
Garcia, A.R.; Johnston, R.G.; Martinez, R.K.
1999-05-25T23:59:59.000Z
A fluid sampling tool is described for sampling fluid from a container. The tool has a fluid collecting portion which is drilled into the container wall, thereby affixing it to the wall. The tool may have a fluid extracting section which withdraws fluid collected by the fluid collecting section. The fluid collecting section has a fluted shank with an end configured to drill a hole into a container wall. The shank has a threaded portion for tapping the borehole. The shank is threadably engaged to a cylindrical housing having an inner axial passageway sealed at one end by a septum. A flexible member having a cylindrical portion and a bulbous portion is provided. The housing can be slid into an inner axial passageway in the cylindrical portion and sealed to the flexible member. The bulbous portion has an outer lip defining an opening. The housing is clamped into the chuck of a drill, the lip of the bulbous section is pressed against a container wall until the shank touches the wall, and the user operates the drill. Wall shavings (kerf) are confined in a chamber formed in the bulbous section as it folds when the shank advances inside the container. After sufficient advancement of the shank, an o-ring makes a seal with the container wall. 6 figs.
Supercritical fluid extraction
Wai, Chien M. (Moscow, ID); Laintz, Kenneth (Pullman, WA)
1994-01-01T23:59:59.000Z
A method of extracting metalloid and metal species from a solid or liquid material by exposing the material to a supercritical fluid solvent containing a chelating agent. The chelating agent forms chelates that are soluble in the supercritical fluid to allow removal of the species from the material. In preferred embodiments, the extraction solvent is supercritical carbon dioxide and the chelating agent is a fluorinated or lipophilic crown ether or fluorinated dithiocarbamate. The method provides an environmentally benign process for removing contaminants from industrial waste without using acids or biologically harmful solvents. The chelate and supercritical fluid can be regenerated, and the contaminant species recovered, to provide an economic, efficient process.
Multiphase fluid characterization system
Sinha, Dipen N.
2014-09-02T23:59:59.000Z
A measurement system and method for permitting multiple independent measurements of several physical parameters of multiphase fluids flowing through pipes are described. Multiple acoustic transducers are placed in acoustic communication with or attached to the outside surface of a section of existing spool (metal pipe), typically less than 3 feet in length, for noninvasive measurements. Sound speed, sound attenuation, fluid density, fluid flow, container wall resonance characteristics, and Doppler measurements for gas volume fraction may be measured simultaneously by the system. Temperature measurements are made using a temperature sensor for oil-cut correction.
MIDDLE ATMOSPHERE DYNAMICS AT707 (3 credits)
., Holton, J. R., Leovy, C. B., Academic Press, 489 pp. Â· Atmospheric and Oceanic Fluid Dynamics, 2006 Review Articles: Â· Haynes, P. H., 2005: Stratospheric Dynamics. Annu. Rev. Fluid Mech., 37, 263Â 293ÂDobson Circulation, Residual (Diabatic) Circulations 7.1 Discovery 7.2 Eliassen's Balanced Response to a Mechanical
Integrable Supersymmetric Fluid Mechanics from Superstrings
Y. Bergner; R. Jackiw
2001-05-03T23:59:59.000Z
Following the construction of a model for the planar supersymmetric Chaplygin gas, supersymmetric fluid mechanics in (1+1)-dimensions is obtained from the light-cone parametrized Nambu-Goto superstring in (2+1)-dimensions. The lineal model is completely integrable and can be formulated neatly using Riemann coordinates. Infinite towers of conserved charges and supercharges are exhibited. They form irreducible representations of a dynamical (hidden) SO(2,1) symmetry group.
Weakly nonlocal fluid mechanics - the Schrodinger equation
P. Van; T. Fulop
2004-06-09T23:59:59.000Z
A weakly nonlocal extension of ideal fluid dynamics is derived from the Second Law of thermodynamics. It is proved that in the reversible limit the additional pressure term can be derived from a potential. The requirement of the additivity of the specific entropy function determines the quantum potential uniquely. The relation to other known derivations of Schr\\"odinger equation (stochastic, Fisher information, exact uncertainty) is clarified.
Circulating Fluid Bed Combustor
Fraley, L. D.; Do, L. N.; Hsiao, K. H.
1982-01-01T23:59:59.000Z
The circulating bed combustor represents an alternative concept of burning coal in fluid bed technology, which offers distinct advantages over both the current conventional fluidized bed combustion system and the pulverized coal boilers equipped...
West, Phillip B. (Idaho Falls, ID)
2006-01-17T23:59:59.000Z
A method and apparatus suitable for coupling seismic or other downhole sensors to a borehole wall in high temperature and pressure environments. In one embodiment, one or more metal bellows mounted to a sensor module are inflated to clamp the sensor module within the borehole and couple an associated seismic sensor to a borehole wall. Once the sensing operation is complete, the bellows are deflated and the sensor module is unclamped by deflation of the metal bellows. In a further embodiment, a magnetic drive pump in a pump module is used to supply fluid pressure for inflating the metal bellows using borehole fluid or fluid from a reservoir. The pump includes a magnetic drive motor configured with a rotor assembly to be exposed to borehole fluid pressure including a rotatable armature for driving an impeller and an associated coil under control of electronics isolated from borehole pressure.
Semans, Joseph P. (Uniontown, PA); Johnson, Peter G. (Pittsburgh, PA); LeBoeuf, Jr., Robert F. (Clairton, PA); Kromka, Joseph A. (Idaho Falls, ID); Goron, Ronald H. (Connellsville, PA); Hay, George D. (Venetia, PA)
1993-01-01T23:59:59.000Z
A trainer, mounted and housed within a mobile console, is used to teach and reinforce fluid principles to students. The system trainer has two centrifugal pumps, each driven by a corresponding two-speed electric motor. The motors are controlled by motor controllers for operating the pumps to circulate the fluid stored within a supply tank through a closed system. The pumps may be connected in series or in parallel. A number of valves are also included within the system to effect different flow paths for the fluid. In addition, temperature and pressure sensing instruments are installed throughout the closed system for measuring the characteristics of the fluid, as it passes through the different valves and pumps. These measurements are indicated on a front panel mounted to the console, as a teaching aid, to allow the students to observe the characteristics of the system.
Brenner, Howard
This paper presents a unified theory of phoretic phenomena in single-component fluids. Simple formulas are given for the phoretic velocities of small inert force-free non-Brownian particles migrating through otherwise ...
Wang, Huhu 1985-
2012-12-13T23:59:59.000Z
if the large portion of the coolant flows into bypass gaps instead of coolant channels in which the cooling efficiency is much higher. A preliminary three dimensional steady-state CFD analysis was performed with commercial code STARCCM+ 6.04 to investigate...
Bothe, Dieter
INTRODUCTION The efficiency of gas-liquid rectors like bubble columns, air-lift or agitated stirred reactors. Especially in case of fast reactions the effi- ciency of chemical reactors significantly depends on the mass6th International Conference on CFD in Oil & Gas, Metallurgical and Process Industries SINTEF
CFD Analysis of a Novel High Speed Rotary On/Off Valve 283 Proc. of 6th
Li, Perry Y.
section, and outlet turbine. A CFD model is created for each section, and then verified. The equations that predict the valve performance has been validated for the inlet rail with nozzles and the outlet turbine, valve design, throttle-less control 1 INTRODUCTION Hydraulic actuation systems have been widely used due
2D Axisymmetric Coupled CFD-kinetics Modeling of a Nonthermal Arc Plasma Torch for Diesel Fuel
Boyer, Edmond
-assisted diesel fuel reformer developed for two different applications: (i) onboard H2 production for fuel cell been also developed for different reforming reactors: solid oxide fuel cell (SOFC)7 , membrane reformer1 2D Axisymmetric Coupled CFD-kinetics Modeling of a Nonthermal Arc Plasma Torch for Diesel Fuel
Oborny, Michael C. (Albuquerque, NM); Paul, Phillip H. (Livermore, CA); Hencken, Kenneth R. (Pleasanton, CA); Frye-Mason, Gregory C. (Cedar Crest, NM); Manginell, Ronald P. (Albuquerque, NM)
2001-01-01T23:59:59.000Z
A valve for controlling fluid flows. This valve, which includes both an actuation device and a valve body provides: the ability to incorporate both the actuation device and valve into a unitary structure that can be placed onto a microchip, the ability to generate higher actuation pressures and thus control higher fluid pressures than conventional microvalves, and a device that draws only microwatts of power. An electrokinetic pump that converts electric potential to hydraulic force is used to operate, or actuate, the valve.
13.811 Advanced Structural Dynamics and Acoustics, Spring 2004
Schmidt, Henrik
Foundations of 3D elasticity. Fluid and elastic wave equations. Elastic and plastic waves in rods and beams. Waves in plates. Interaction with an acoustic fluid. Dynamics and acoustics of cylindrical shells. Radiation and ...
R. Caimmi
2006-07-27T23:59:59.000Z
With regard to large-scale astrophysical systems, the current paper deals with (i) formulation of tensor virial equations from the standpoint of analytical mechanics; (ii) investigation on the role of systematic and random motions for virial equilibrium configurations; (iii) extent to which systematic and random motions are equivalent in changing a fluid shape. The tensor virial equations are formulated using analytical mechanics, and the self potential-energy tensor is shown to be symmetric. The role of systematic and random motions in collisionless, ideal, self-gravitating fluids, is analysed in detail including radial and tangential velocity dispersion on the equatorial plane. R3 fluids are defined as ideal, self-gravitating fluids in virial equilibrium, with systematic rotation around a principal axis of inertia, and ihe related virial equations are formulated. A unified theory of systematic and random motions is developed for R3 fluids, taking into consideration imaginary rotation. The effect of random motion excess is shown to be equivalent to an additional real or imaginary rotation, respectively, inducing flattening or elongation. R3 fluids are found to admit adjoint configurations with isotropic random velocity distribution. Further constraints are established on the amount of random velocity anisotropy along the principal axes, for triaxial configurations. A necessary condition is formulated for the occurrence of bifurcation points from axisymmetric to triaxial configurations in virial equilibrium, which is independent of the anisotropy parameters. In the special case of homeoidally striated Jacobi ellipsoid, some previously known results are reproduced.
Diffusion Enhancement in Core-softened fluid confined in nanotubes
José R. Bordin; Alan B. de Oliveira; Alexandre Diehl; Marcia C. Barbosa
2012-08-05T23:59:59.000Z
We study the effect of confinement in the dynamical behavior of a core-softened fluid. The fluid is modeled as a two length scales potential. This potential in the bulk reproduces the anomalous behavior observed in the density and in the diffusion of liquid water. A series of $NpT$ Molecular Dynamics simulations for this two length scales fluid confined in a nanotube were performed. We obtain that the diffusion coefficient increases with the increase of the nanotube radius for wide channels as expected for normal fluids. However, for narrow channels, the confinement shows an enhancement in the diffusion coefficient when the nanotube radius decreases. This behavior, observed for water, is explained in the framework of the two length scales potential.
Lecture notes Introductory fluid mechanics
Malham, Simon J.A.
Lecture notes Introductory fluid mechanics Simon J.A. Malham Simon J.A. Malham (22nd February 2013 of fluid mechanics and along the way see lots of interesting applications. 2 Fluid flow 2.1 Flow A material essential to all modern car braking mechanisms. Fluids can be further subcatergorized. There are ideal
Lecture notes Introductory fluid mechanics
Malham, Simon J.A.
Lecture notes Introductory fluid mechanics Simon J.A. Malham Simon J.A. Malham (17th March 2014 of fluid mechanics and along the way see lots of interesting applications. 2 Fluid flow, the Continuum are generally incompressible--a feature essential to all modern car braking mechanisms. Fluids can be further
Fluid Mechanics and Homeland Security
Settles, Gary S.
Fluid Mechanics and Homeland Security Gary S. Settles Mechanical and Nuclear Engineering Department. 2006. 38:87Â110 The Annual Review of Fluid Mechanics is online at fluid.annualreviews.org doi: 10 security involves many applications of fluid mechanics and offers many opportunities for research
E-Print Network 3.0 - aiaa cfd drag Sample Search Results
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
90 N-S 19... ., Jeong, S. and Chiba, K., "Multi-Objective Design Exploration for Aerodynamic Configurations," AIAA ... Source: Obayashi, Shigeru - Institute of Fluid Science,...
Non-relativistic conformal symmetries in fluid mechanics
P. -M. Zhang; P. A. Horvathy
2009-10-24T23:59:59.000Z
The symmetries of a free incompressible fluid span the Galilei group, augmented with independent dilations of space and time. When the fluid is compressible, the symmetry is enlarged to the expanded Schroedinger group, which also involves, in addition, Schroedinger expansions. While incompressible fluid dynamics can be derived as an appropriate non-relativistic limit of a conformally-invariant relativistic theory, the recently discussed Conformal Galilei group, obtained by contraction from the relativistic conformal group, is not a symmetry. This is explained by the subtleties of the non-relativistic limit.
Nonrelativistic Dark-Energy Fluid in a Baby Universe
P. C. Stichel; W. J. Zakrzewski
2008-07-23T23:59:59.000Z
We show that the dynamical realization of the acceleration-enlarged Galilean symmetry leads to nonrelativistic massless particles whose energy may be negative. We present a fluid mechanical generalisation of this observation and use it to contruct a nonrelativistic two-dimensional fluid model which possesses solutions with a negative energy density. Considering this model as describing dark energy in a baby universe (two space dimensions) we show that its negative energy density leads to a repulsive gravitational interaction of the fluid with any test body.
Fluid driven recipricating apparatus
Whitehead, John C. (Davis, CA)
1997-01-01T23:59:59.000Z
An apparatus comprising a pair of fluid driven pump assemblies in a back-to-back configuration to yield a bi-directional pump. Each of the pump assemblies includes a piston or diaphragm which divides a chamber therein to define a power section and a pumping section. An intake-exhaust valve is connected to each of the power sections of the pump chambers, and function to direct fluid, such as compressed air, into the power section and exhaust fluid therefrom. At least one of the pistons or diaphragms is connected by a rod assembly which is constructed to define a signal valve, whereby the intake-exhaust valve of one pump assembly is controlled by the position or location of the piston or diaphragm in the other pump assembly through the operation of the rod assembly signal valve. Each of the pumping sections of the pump assemblies are provided with intake and exhaust valves to enable filling of the pumping section with fluid and discharging fluid therefrom when a desired pressure has been reached.
Fluid driven reciprocating apparatus
Whitehead, J.C.
1997-04-01T23:59:59.000Z
An apparatus is described comprising a pair of fluid driven pump assemblies in a back-to-back configuration to yield a bi-directional pump. Each of the pump assemblies includes a piston or diaphragm which divides a chamber therein to define a power section and a pumping section. An intake-exhaust valve is connected to each of the power sections of the pump chambers, and function to direct fluid, such as compressed air, into the power section and exhaust fluid therefrom. At least one of the pistons or diaphragms is connected by a rod assembly which is constructed to define a signal valve, whereby the intake-exhaust valve of one pump assembly is controlled by the position or location of the piston or diaphragm in the other pump assembly through the operation of the rod assembly signal valve. Each of the pumping sections of the pump assemblies are provided with intake and exhaust valves to enable filling of the pumping section with fluid and discharging fluid therefrom when a desired pressure has been reached. 13 figs.
Full Life Wind Turbine Gearbox Lubricating Fluids
Lutz, Glenn A.; Jungk, Manfred; Bryant, Jonathan J.; Lauer, Rebecca S.; Chobot, Anthony; Mayer, Tyler; Palmer, Shane; Kauffman, Robert E.
2012-02-28T23:59:59.000Z
Industrial gear box lubricants typically are hydrocarbon based mineral oils with considerable amounts of additives to overcome the lack of base fluid properties like wear protection, oxidation stability, load carrying capacity, low temperature solidification and drop of viscosity at higher temperatures. For today's wind turbine gearboxes, the requirements are more severe and synthetic hydrocarbon oils are used to improve on this, but all such hydrocarbon based lubricants require significant amounts of Extreme Pressure (EP) additives to meet performance requirements. Perfluoropolyether (PFPE) fluids provide load carrying capacity as an inherent property. During the course of the project with the main tasks of 'Establish a Benchmark', 'Lubricant Evaluation', 'Full Scale Gearbox Trial' and 'Economic Evaluation', the PAO Reference oil exhibited significant changes after laboratory gear testing, in service operation in the field and full scale gearbox trial. Four hydrocarbon base oils were selected for comparison in the benchmarking exercise and showed variation with respect to meeting the requirements for the laboratory micro-pitting tests, while the PFPE fluid exceeded the requirements even with the material taken after the full scale gear box trial. This is remarkable for a lubricant without EP additives. Laboratory bearing tests performed on the PFPE fluids before and after the full scale gear box trial showed the results met requirements for the industry standard. The PFPE fluid successfully completed the full scale gear box test program which included baseline and progressive staged load testing. The evaluation of gears showed no micro-pitting or objectionable wear. By the final stage, lubricant film thickness had been reduced to just 21% of its original value, this was by design and resulted in a lambda ratio of well below 1. This test design scenario of a low lambda ratio is a very undesirable lubrication condition for real world but creates the ability to test the lubricating fluids performance under the most extreme conditions. The PAO Reference oil also passed its testing without any noticeable deterioration of the gear surface. However the PAO Reference oil was replaced midway through the progressive loading, as the lubricant was burned in an attempt to raise the sump temperature to the same levels as for the PFPE. Both materials experienced a decrease of viscosity during their respective run times. The viscosity index decreased for the PAO there while there was a slight increase for the PFPE. FZG laboratory gear tests and measurements of the drive motor's current during the full scale gear box trial were made to characterize the relative efficiency between the PFPE fluid and the PAO Reference oil. In the FZG laboratory efficiency test, the PFPE fluids show much higher churning losses due to their higher viscosity and density. The analysis seems to show that the efficiency correlates better to dynamic viscosity than any other of the measured metrics such as film thickness. In load stages where the load, speed and temperature are similar, the PFPE fluid has a greater film thickness and theoretical gear protection, but requires a larger current for the drive motor than the PAO. However in load stages where the film thickness is the same, the PFPE fluid's reduced dynamic viscosity gives it a slight efficiency advantage relative to the PAO reference oil. Ultimately, many factors such as temperature, rotational speed, and fluid viscosity combine in a complex fashion to influence the results. However, the PFPE's much lower change of viscosity with respect to temperature, allows variations in designing an optimum viscosity to balance efficiency versus gear protection. Economic analysis was done using Cost of Energy calculations. The results vary from 5.3% for a 'Likely Case' to 16.8% for a 'Best Case' scenario as potential cost improvement by using PFPE as the gearbox lubricating fluid. It is important to note the largest portion of savings comes in Levelized Replacement Cost, which is dictated by the assumption on gearb
Garbe, Christoph S.
16th Int Symp on Applications of Laser Techniques to Fluid Mechanics Lisbon, Portugal, 9Â12 July we compare state-of-the-art fluid motion estimation algorithms with respect to the application information to retrieve the motion. 1. Introduction Todays image motion algorithms in fluid dynamics
Universal fluid droplet ejector
Lee, E.R.; Perl, M.L.
1999-08-24T23:59:59.000Z
A droplet generator comprises a fluid reservoir having a side wall made of glass or quartz, and an end cap made from a silicon plate. The end cap contains a micromachined aperture through which the fluid is ejected. The side wall is thermally fused to the end cap, and no adhesive is necessary. This means that the fluid only comes into contact with the side wall and the end cap, both of which are chemically inert. Amplitudes of drive pulses received by reservoir determine the horizontal displacements of droplets relative to the ejection aperture. The drive pulses are varied such that the dropper generates a two-dimensional array of vertically-falling droplets. Vertical and horizontal inter-droplet spacings may be varied in real time. Applications include droplet analysis experiments such as Millikan fractional charge searches and aerosol characterization, as well as material deposition applications. 8 figs.
Universal fluid droplet ejector
Lee, Eric R. (Redwood City, CA); Perl, Martin L. (Palo Alto, CA)
1999-08-24T23:59:59.000Z
A droplet generator comprises a fluid reservoir having a side wall made of glass or quartz, and an end cap made from a silicon plate. The end cap contains a micromachined aperture through which the fluid is ejected. The side wall is thermally fused to the end cap, and no adhesive is necessary. This means that the fluid only comes into contact with the side wall and the end cap, both of which are chemically inert. Amplitudes of drive pulses received by reservoir determine the horizontal displacements of droplets relative to the ejection aperture. The drive pulses are varied such that the dropper generates a two-dimensional array of vertically-falling droplets. Vertical and horizontal interdroplet spacings may be varied in real time. Applications include droplet analysis experiments such as Millikan fractional charge searches and aerosol characterization, as well as material deposition applications.
Development of an analytical model for organic-fluid fouling
Panchal, C.B.; Watkinson, A.P.
1994-10-01T23:59:59.000Z
The research goal of this project is to determine ways to effectively mitigate fouling in organic fluids: hydrocarbons and derived fluids. The fouling research focuses on the development of methodology for determining threshold conditions for fouling. Initially, fluid containing chemicals known to produce foulant is analyzed; subsequently, fouling of industrial fluids is investigated. The fouling model developed for determining the effects of physical parameters is the subject of this report. The fouling model is developed on the premise that the chemical reaction for generation of precursor can take place in the bulk fluid, in the thermal-boundary layer, or at the fluid/wall interface, depending upon the interactive effects of fluid dynamics, heat and mass transfer, and the controlling chemical reaction. In the analysis, the experimental data are examined for fouling deposition of polyperoxide produced by autoxidation of indene in kerosene. The effects of fluid and wall temperatures for two flow geometries are analyzed. The results show that the relative effects of physical parameters on the fouling rate differ for the three fouling mechanisms. Therefore, to apply the closed-flow-loop data to industrial conditions, the controlling mechanism must be identified.
Geophysical Fluid Dynamics What does the Geophysical Fluid Dynamics Laboratory do for the Nation?
) 2015 President's budget request for modeling system for predictions and projections on time scales from days to decades. The Fiscal Year (FY
Accurate static and dynamic properties of liquid electrolytes...
Office of Scientific and Technical Information (OSTI)
electrolytes. However, to date, almost all molecular-dynamics simulations of these fluids rely on classical force fields, while a complete description of the functionality of...
TRACING FLUID SOURCES IN THE COSO GEOTHERMAL SYSTEM USING FLUID...
TRACING FLUID SOURCES IN THE COSO GEOTHERMAL SYSTEM USING FLUID-INCLUSION GAS CHEMISTRY Jump to: navigation, search OpenEI Reference LibraryAdd to library Conference Proceedings:...
The influence of fluid properties on the success of hydraulic fracturing operations
Power, D.J.; Boger, D.V. [Univ. of Melbourne, Victoria (Australia); Paterson, L.
1994-12-31T23:59:59.000Z
Hydroxypropylguar based fluids are the most commonly used fluids for hydraulic fracturing. Through the addition of borate ions the polymer present in the fluid can crosslink to form a high viscosity gel. Prior to placement in the fracture the fluid is required to have a low viscosity to minimize friction losses in the tubular goods. A high viscosity fluid is required in the fracture for several reasons, primarily to suspend the proppant and to minimize fluid loss into the formation. This paper describes a new method which can be used to model the gelation reaction of crosslinking fluids. By modeling the dynamic properties of the fluid it is possible to predict the physical state of the fluid at any time during a fracturing treatment. Small amplitude oscillatory measurements are applied to fluid samples in a cone-and-plate geometry. The change in the dynamic properties with time can be fitted to a simple model which can then be used to determine the gel time for the fluid. Methods used to distinguish between the liquid and gel state are also discussed.
Magnetically stimulated fluid flow patterns
Martin, Jim; Solis, Kyle
2014-08-06T23:59:59.000Z
Sandia National Laboratories' Jim Martin and Kyle Solis explain research on the effects of magnetic fields on fluid flows and how they stimulate vigorous flows. Fluid flow is a necessary phenomenon in everything from reactors to cooling engines in cars.
Massively-parallel Spectral Element Algorithm Development for High Speed Flows
Camp, Joshua Lane
2013-10-07T23:59:59.000Z
Fluid Dynamics in the Design Cycle . . . . . . . . . . 3 1.2.1 Nature of the Flow Equations and Turbulence . . . . . . . . . 3 1.2.2 Industrial CFD Use . . . . . . . . . . . . . . . . . . . . . . . . 5 1.2.3 Massive-parallelism and CFD... . . . . . . . . . . . . . . . . . . 7 1.2.4 Towards Improving Design Cycle Analysis . . . . . . . . . . . 7 1.3 Keys for Effective High-Fidelity CFD . . . . . . . . . . . . . . . . . . 9 1.3.1 Need for High Order . . . . . . . . . . . . . . . . . . . . . . . 9 1.3.2 Need for High...
Transport in non-conformal holographic fluids
Shailesh Kulkarni; Bum-Hoon Lee; Jae-Hyuk Oh; Chanyong Park; Raju Roychowdhury
2013-03-06T23:59:59.000Z
We have considered non-conformal fluid dynamics whose gravity dual is a certain Einstein dilaton system with Liouville type dilaton potential, characterized by an intrinsic parameter $\\eta$. We have discussed the Hawking-Page transition in this framework using hard-wall model and it turns out that the critical temperature of the Hawking-Page transition encapsulates a non-trivial dependence on $\\eta$. We also obtained transport coefficients such as AC conductivity, shear viscosity and diffusion constant in the hydrodynamic limit, which show non-trivial $\\eta$ dependent deviations from those in conformal fluids, although the ratio of the shear viscosity to entropy density is found to saturate the universal bound. Some of the retarded correlators are also computed in the high frequency limit for case study.
Method and apparatus for controlling fluid flow
Miller, J.R.
1980-06-27T23:59:59.000Z
A method and apparatus for precisely controlling the rate (and hence amount) of fluid flow are given. The controlled flow rate is finely adjustable, can be extremely small (on the order of microliter-atmospheres per second), can be adjusted to zero (flow stopped), and is stable to better than 1% with time. The dead volume of the valve can be made arbitrarily small, in fact essentially zero. The valve employs no wearing mechanical parts (including springs, stems, or seals). The valve is finely adjustable, has a flow rate dynamic range of many decades, can be made compatible with any fluid, and is suitable for incorporation into an open or closed loop servo-control system.
Barter, Garrett E. (Garrett Ehud), 1979-
2008-01-01T23:59:59.000Z
The accurate simulation of supersonic and hypersonic flows is well suited to higher-order (p > 1), adaptive computational fluid dynamics (CFD). Since these cases involve flow velocities greater than the speed of sound, an ...
Barter, Garrett Ehud
The accurate simulation of supersonic and hypersonic flows is well suited to higher-order (p > 1), adaptive computational fluid dynamics (CFD). Since these cases involve flow velocities greater than the speed of sound, an ...
El-Sawi, A.; Haghighat, F.; Akbari, H.
2013-01-01T23:59:59.000Z
A simulation tool is developed to analyze the thermal performance of a centralized latent heat thermal energy storage system (LHTES) using computational fluid dynamics (CFD). The LHTES system is integrated with a mechanical ventilation system...
Helton, Donald McLean
2002-01-01T23:59:59.000Z
The premise of the work presented here is to use a common analytical tool, Computational Fluid Dynamics (CFD), along with a prevalent turbulence model, Large Eddy Simulation (LES), to study the flow past rectangular cylinders. In an attempt to use...
Sekaran, Aarthi
2010-10-12T23:59:59.000Z
The study of the effect of different orbit paths and whirl ratios on the rotordynamic coefficients of a smooth eccentric annular seal, using Computational Fluid Dynamics (CFD) was performed. The flow was simulated for two different orbits - linear...
Holik III, Eddie Frank (Trey)
2009-05-15T23:59:59.000Z
. In this work, a magnetohydrodynamic (MHD) model is used along with a computational fluid dynamic (CFD) software package called FLUENT© to simulate an ICPT. To solve the electromagnetic equations and incorporate forces and resistive heating, several userdefined...
CX-004511: Categorical Exclusion Determination
Broader source: Energy.gov [DOE]
Displacement and Mixing in Subsea Jumpers Experimental Data and Computational Fluid Dynamics (CFD)CX(s) Applied: A9, A11Date: 11/22/2010Location(s): Tulsa, OklahomaOffice(s): Fossil Energy, National Energy Technology Laboratory
Unsteady adjoint analysis for output sensitivity and mesh adaptation
Krakos, Joshua Ambre
2012-01-01T23:59:59.000Z
Adjoint analysis in computational fluid dynamics (CFD) has been applied to design optimization and mesh adaptation, but due to the relative expense of unsteady analysis these applications have predominantly been for steady ...
Duan, X.
Nucleate boiling is important in many energy systems including light water reactors. Currently significant efforts are underway to develop mechanisticmodels for nucleate boiling based on computational fluid dynamics (CFD). ...
Lecture notes Ideal fluid mechanics
Malham, Simon J.A.
Lecture notes Ideal fluid mechanics Simon J.A. Malham Simon J.A. Malham (6th Feb 2010) Maxwell and in the process learn about the subtleties of fluid mechanics and along the way see lots of interesting are generally incompressible--a feature essential to all modern car braking mechanisms. Fluids can be further
Dabiri, John O.
Journal of Fluid Mechanics 25 March 2009 VOLUME 623 Journal of Fluid Mechanics 25 Mar. 2009 VOLUME 623 #12;J. Fluid Mech. (2009), vol. 623, pp. 75Â84. c 2009 Cambridge University Press doi:10.1017/SLCS and the capture region enable analysis of the effect of several physiological and mechanical parameters
Short communication Study of pollution dispersion in urban areas using
Yu, K.N.
of the Reynolds numbers covers the laminar, transitional and part of the turbulent regimes of the flow (CFD) and Geographic Information System (GIS) A.K.M. Chua , R.C.W. Kwokb , K.N. Yua, * a Department rights reserved. Keywords: Street canyons; Computational Fluid Dynamics; CFD; CFX; Geographic Information
Ris-R-1543(EN) Aerodynamic investigation of Winglets on
RisÃ¸-R-1543(EN) Aerodynamic investigation of Winglets on Wind Turbine Blades using CFD Jeppe Johansen and Niels N. SÃ¸rensen Title: Aerodynamic investigation of Winglets on Wind Turbine Blades using of the aerodynamics around a wind turbine blade with a winglet using Computational Fluid Dynamics, CFD. Five winglets
Pedersen, Tom
Turbine Performance M. Shives1 and C. Crawford2 Dept. of Mechanical Engineering, University of Victoria turbine designs using computational fluid dynamics (CFD) simulation. Analytical model coefficients is proposed for the base pressure coefficient. Keywords: base-pressure, CFD, diffuser-augmented turbine, tidal
Wind power resource assessment in complex urban environments
in Computational Fluid Dynamics (CFD) methods holds potential for the advancement of wind energy resource buildings. CFD simulations have been used to evaluate the wind energy potential on the campus. 2 Objectives The aim of this study is to assess wind energy resource on the MIT campus for potential
Oscillating fluid power generator
Morris, David C
2014-02-25T23:59:59.000Z
A system and method for harvesting the kinetic energy of a fluid flow for power generation with a vertically oriented, aerodynamic wing structure comprising one or more airfoil elements pivotably attached to a mast. When activated by the moving fluid stream, the wing structure oscillates back and forth, generating lift first in one direction then in the opposite direction. This oscillating movement is converted to unidirectional rotational movement in order to provide motive power to an electricity generator. Unlike other oscillating devices, this device is designed to harvest the maximum aerodynamic lift forces available for a given oscillation cycle. Because the system is not subjected to the same intense forces and stresses as turbine systems, it can be constructed less expensively, reducing the cost of electricity generation. The system can be grouped in more compact clusters, be less evident in the landscape, and present reduced risk to avian species.
Fluid-fluid versus fluid-solid demixing in mixtures of parallel hard hypercubes
Luis Lafuente; Yuri Martinez-Raton
2011-02-08T23:59:59.000Z
It is well known that the increase of the spatial dimensionality enhances the fluid-fluid demixing of a binary mixture of hard hyperspheres, i.e. the demixing occurs for lower mixture size asymmetry as compared to the three-dimensional case. However, according to simulations, in the latter dimension the fluid-fluid demixing is metastable with respect to the fluid-solid transition. According to the results obtained from approximations to the equation of state of hard hyperspheres in higher dimensions, the fluid-fluid demixing might becomes stable for high enough dimension. However, this conclusion is rather speculative since none of the above works have taken into account the stability of the crystalline phase (nor by a minimization of a given density functional, neither spinodal calculations or MC simulations). Of course, the lack of results is justified by the difficulty for performing density functional calculations or simulations in high dimensions and, in particular, for highly asymmetric binary mixtures. In the present work, we will take advantage of a well tested theoretical tool, namely the fundamental measure density functional theory for parallel hard hypercubes (in the continuum and in the hypercubic lattice). With this, we have calculated the fluid-fluid and fluid-solid spinodals for different spatial dimensions. We have obtained, no matter of the dimensionality, the mixture size asymmetry nor the polydispersity (included as a bimodal distribution function centered around the asymmetric edge-lengths), that the fluid-fluid critical point is always located above the fluid-solid spinodal. In conclusion, these results point to the existence of demixing between at least one solid phase rich in large particles and one fluid phase rich in small ones, preempting a fluid-fluid demixing, independently of the spatial dimension or the polydispersity.
Downhole Fluid Analyzer Development
Bill Turner
2006-11-28T23:59:59.000Z
A novel fiber optic downhole fluid analyzer has been developed for operation in production wells. This device will allow real-time determination of the oil, gas and water fractions of fluids from different zones in a multizone or multilateral completion environment. The device uses near infrared spectroscopy and induced fluorescence measurement to unambiguously determine the oil, water and gas concentrations at all but the highest water cuts. The only downhole components of the system are the fiber optic cable and windows. All of the active components--light sources, sensors, detection electronics and software--will be located at the surface, and will be able to operate multiple downhole probes. Laboratory testing has demonstrated that the sensor can accurately determine oil, water and gas fractions with a less than 5 percent standard error. Once installed in an intelligent completion, this sensor will give the operating company timely information about the fluids arising from various zones or multilaterals in a complex completion pattern, allowing informed decisions to be made on controlling production. The research and development tasks are discussed along with a market analysis.
Why are Fluid Densities So Low in Carbon Nanotubes?
Gerald J. Wang; Nicolas G. Hadjiconstantinou
2014-09-27T23:59:59.000Z
The equilibrium density of fluids under nanoconfinement can differ substantially from their bulk density. Using a mean-field approach to describe the energetic landscape near the carbon nanotube (CNT) wall, we obtain analytical results describing the lengthscales associated with the layering observed at the fluid-CNT interface. When combined with molecular simulation results for the fluid density in the layered region, this approach allows us to derive a closed-form prediction for the overall equilibrium fluid density as a function of the CNT radius that is in excellent agreement with molecular dynamics simulations. We also show how aspects of this theory can be extended to describe water confined within CNTs and find good agreement with results from the literature.
Coalescence of bubbles and drops in an outer fluid
Joseph D. Paulsen; Rémi Carmigniani; Anerudh Kannan; Justin C. Burton; Sidney R. Nagel
2014-07-24T23:59:59.000Z
When two liquid drops touch, a microscopic connecting liquid bridge forms and rapidly grows as the two drops merge into one. Whereas coalescence has been thoroughly studied when drops coalesce in vacuum or air, many important situations involve coalescence in a dense surrounding fluid, such as oil coalescence in brine. Here we study the merging of gas bubbles and liquid drops in an external fluid. Our data indicate that the flows occur over much larger length scales in the outer fluid than inside the drops themselves. Thus we find that the asymptotic early regime is always dominated by the viscosity of the drops, independent of the external fluid. A phase diagram showing the crossovers into the different possible late-time dynamics identifies a dimensionless number that signifies when the external viscosity can be important.
Statistical Estimation of Fluid Flow Fields Johnny Chang David Edwards Yizhou Yu
Yu, Yizhou
their motion fields. 1 Introduction Dynamic fluids, such as rivers, ocean waves, moving clouds, smoke and fires (4) where is the kinematic viscosity of the fluid, is its den- sity and f is an external force scale. A good ex- ample is the changing surface geometry of a water surface. This is because the self
Numerical modeling of heat transfer and fluid flow in rotor-stator cavities with throughflow
Boyer, Edmond
Numerical modeling of heat transfer and fluid flow in rotor-stator cavities with throughflow S the dynamical effects from the heat transfer process. The fluid flow in an enclosed disk system with axial with heat transfer along the stator, which corresponds to the experiment of Djaoui et al. [2]. Our results
Roy, Subrata
devices. Mechanical micropumps drive the working fluid through a membrane or diaphragm, while non-mechanical1 American Institute of Aeronautics and Astronautics Three-dimensional Plasma and Fluid Flow Plasma Dynamics Laboratory and Test Facility Mechanical and Aerospace Engineering Department University
Proceedings of FEDSM'03: ASME/JSME Joint Fluids Engineering Conference
Roy, Subrata
Proceedings of FEDSM'03: 4th ASME/JSME Joint Fluids Engineering Conference Honolulu, Hawaii, USA Reni Raju and Subrata Roy Computational Plasma Dynamics Laboratory Department of Mechanical Engineering is no longer valid as the mean free path of the fluid becomes comparable to the dimension of the system
Proceedings of FEDSM2006 2006 ASME Joint U.S. -European Fluids Engineering Summer Meeting
Roy, Subrata
Proceedings of FEDSM2006 2006 ASME Joint U.S. - European Fluids Engineering Summer Meeting July 17: Datta.Gaitonde@wpafb.af.mil Subrata Roy Computational Plasma Dynamics Laboratory Mechanical Engineering of the latter approach, a proce- dure to couple unsteady force fields obtained from multi-fluid models to very
Tirtaatmadja, Viyada
2007-01-23T23:59:59.000Z
The dynamics of drop formation and pinch-off have been investigated for a series of low viscosity elastic fluids possessing similar shear viscosities, but differing substantially in elastic properties. On initial approach ...
Breault, Ronald W, [U.S. DOE; Huckaby, Ernest D. [U.S. DOE; Shadle, Lawrence J [U.S. DOE; Spenik, James L. [REM Engineering PLLC
2013-01-01T23:59:59.000Z
The National Energy Technology Laboratory is investigating a new process for CO{sub 2} capture from large sources such as utility power generation facilities as an alternative to liquid amine based absorption processes. Many, but not all of these advanced dry processes are based upon sorbents composed of supported polyamines. In this analysis, experiments have been conducted in a small facility at different temperatures and compared to CFD reactor predictions using kinetics obtained from TGA tests. This particular investigation compares the predicted performance and the experimental performance of one of these new class of sorbents in a fluidized bed reactor. In the experiment, the sorbent absorbs CO{sub 2} from simulated flue gas in a riser reactor, separates the carbonated particles from the de-carbonated flue gas in a cyclone and then regenerates the sorbent, creating a concentrated stream of pure CO{sub 2} for sequestration. In this work, experimental measurements of adsorption are compared to predictions from a 3-dimensional non-isothermal reacting multiphase flow model. The effects of the gas flow rate and reactor temperature are explored. It is shown that the time duration for CO{sub 2} adsorption decreased for an increase in the gas flow. The details of the experimental facility and the model as well as the comparative analysis between the data and the simulation results are discussed.
PAPER B3: PHYSICS OF FLUID FLOWS Hilary Term 2010
Read, Peter L.
,...) Â· Aerodynamics Â important advances in fluid dynamics c. 1900 Â still active today Â· Lubrication of mechanical systems Â· Industry Â e.g. gases in pipes, polymer flows Â· Oil extraction Â liquids flowing through eff n, where `effective diameter' deff 0.3 nm, say. 2 Ã? 10-7 m = 200 nm. In FD, we consider scales
BEE 3310. Bio-Fluid Mechanics Fall Semester 2007
Walter, M.Todd
/8/08 Ethical behavior statement: Home work assignments are due every Wednesday at the beginning of the class of continuity; conservations of mass, energy and momentum and their applications; laminar and turbulent flows Â· Hydrostatics, and fluid dynamics -- conservations of mass, energy, and momentum and their applications
FLUID MECHANICS AND HEAT TRANSFER OF ELECTRON FLOW IN SEMICONDUCTORS
Sen, Mihir
= heat, f = LO-mode, g = LO, h = LA-mode, i = negligible, j = remote heat sink 7/ 70 #12;Heat conductionFLUID MECHANICS AND HEAT TRANSFER OF ELECTRON FLOW IN SEMICONDUCTORS Mihir Sen Department Â· Shallow water analogy Â· Vorticity dynamics Â· Linear stability analysis Â· Numerical simulations of heat
Momentum spectra, anisotropic flow, and ideal fluids
N. Borghini; J. -Y. Ollitrault
2006-07-28T23:59:59.000Z
If the matter produced in ultrarelativistic heavy-ion collisions reaches thermal equilibrium, its subsequent evolution follows the laws of ideal fluid dynamics. We show that general predictions can be made on this basis alone, irrespective of the details of the hydrodynamical model. We derive several scaling rules for momentum spectra and anisotropic flow (in particular the elliptic flow, v2, and the hexadecupole flow, v4) of identified particles. Comparison with existing data is briefly discussed, and qualitative predictions are made for LHC.
Causal relativistic hydrodynamics for viscous fluids
Ulrich W Heinz; Huichao Song
2008-06-03T23:59:59.000Z
We report on recent results from VISH2+1, a code that solves the relativistic Israel-Stewart equations for causal viscous hydrodynamics for heavy-ion collisions with longitudinal boost invariance. We find that even ``minimal'' shear viscosity eta/s=hbar/(4pi) leads to a large reduction of elliptic flow compared to ideal fluid dynamics. We explore systematically the sensitivity of this reduction to the equation of state, system size, initial conditions, and the microscopic relaxation time in different formulations of the Israel-Stewart equations.
Barths, H. [HFV6 Performance and Emissions, GM Powertrain, MC: 480-712-140, 30003 Van Dyke Ave, Warren, MI 48090 (United States); Felsch, C.; Peters, N. [Institut fuer Technische Verbrennung, RWTH Aachen University, Templergraben 64, 52056 Aachen (Germany)
2008-11-15T23:59:59.000Z
The objective of this work is the development of a consistent mixing model for the two-way-coupling of a CFD code and a multi-zone code based on multiple zero-dimensional reactors. The two-way-coupling allows for a computationally efficient modeling of HCCI combustion. The physical domain in the CFD code is subdivided into multiple zones based on three phase variables (fuel mixture fraction, dilution, and total enthalpy). Those phase variables are sufficient for the description of the thermodynamic state of each zone, assuming that each zone is at the same pressure. Each zone in the CFD code is represented by a corresponding zone in the zero-dimensional code. The zero-dimensional code solves the chemistry for each zone, and the heat release is fed back into the CFD code. The difficulty in facing this kind of methodology is to keep the thermodynamic state of each zone consistent between the CFD code and the zero-dimensional code after the initialization of the zones in the multi-zone code has taken place. The thermodynamic state of each zone (and thereby the phase variables) will change in time due to mixing and source terms (e.g., vaporization of fuel, wall heat transfer). The focus of this work lies on a consistent description of the mixing between the zones in phase space in the zero-dimensional code, based on the solution of the CFD code. Two mixing models with different degrees of accuracy, complexity, and numerical effort are described. The most elaborate mixing model (and an appropriate treatment of the source terms) keeps the thermodynamic state of the zones in the CFD code and the zero-dimensional code identical. The models are applied to a test case of HCCI combustion in an engine. (author)
Barths, H. [HFV6 Performance and Emissions, GM Powertrain, MC: 480-712-140, 30003 Van Dyke Ave, Warren, MI 48090 (United States); Felsch, C.; Peters, N. [Institut fuer Technische Verbrennung, RWTH Aachen University, Templergraben 64, 52056 Aachen (Germany)
2009-01-15T23:59:59.000Z
The objective of this work is the development of a consistent mixing model for the two-way-coupling of a CFD code and a multi-zone code based on multiple zero-dimensional reactors. The two-way-coupling allows for a computationally efficient modeling of HCCI combustion. The physical domain in the CFD code is subdivided into multiple zones based on three phase variables (fuel mixture fraction, dilution, and total enthalpy). Those phase variables are sufficient for the description of the thermodynamic state of each zone, assuming that each zone is at the same pressure. Each zone in the CFD code is represented by a corresponding zone in the zero-dimensional code. The zero-dimensional code solves the chemistry for each zone, and the heat release is fed back into the CFD code. The difficulty in facing this kind of methodology is to keep the thermodynamic state of each zone consistent between the CFD code and the zero-dimensional code after the initialization of the zones in the multi-zone code has taken place. The thermodynamic state of each zone (and thereby the phase variables) will change in time due to mixing and source terms (e.g., vaporization of fuel, wall heat transfer). The focus of this work lies on a consistent description of the mixing between the zones in phase space in the zero-dimensional code, based on the solution of the CFD code. Two mixing models with different degrees of accuracy, complexity, and numerical effort are described. The most elaborate mixing model (and an appropriate treatment of the source terms) keeps the thermodynamic state of the zones in the CFD code and the zero-dimensional code identical. The models are applied to a test case of HCCI combustion in an engine. (author)
LUBRICANTS AND HYDRAULIC FLUIDS
Engineer Manual Department
Contents) Major General, USA Chief of Staff i Table of Contents Purpose ........................................................ 1-1 1-1 Applicability .................................................... 1-2 1-1 References ...................................................... 1-3 1-1 Distribution Statement ............................................. 1-4 1-1 Scope ......................................................... 1-5 1-2 Friction ........................................................ 2-1 2-1 Wear .......................................................... 2-2 2-4 Lubrication and Lubricants ......................................... 2-3 2-6 Hydrodynamic or Fluid Film Lubrication ............................... 2-4 2-6 Boundary Lubrication ............................................. 2-5 2-8 Extreme Pressure (EP) Lubrication ................................... 2-6 2-9 Elastohydrodynamic (EHD) Lubrication ................................ 2-7 2-9 Oil R
Wojciech Florkowski; Radoslaw Maj
2013-09-11T23:59:59.000Z
The recently introduced approach describing coupled quark and gluon anisotropic fluids is generalized to include explicitly the transitions between quarks and gluons. We study the effects of such processes on the thermalization rate of anisotropic systems. We find that the quark-gluon transitions may enhance the overall thermalization rate in the cases where the initial momentum anisotropies correspond to mixed oblate-prolate or prolate configurations. On the other hand, no effect on the thermalization rate is found in the case of oblate configurations. The observed regularities are connected with the late-time behavior of the analyzed systems which is described either by the exponential decay or the power law.
Ultrasonic fluid quality sensor system
Gomm, Tyler J. (Meridian, ID); Kraft, Nancy C. (Idaho Falls, ID); Phelps, Larry D. (Pocatello, ID); Taylor, Steven C. (Idaho Falls, ID)
2002-10-08T23:59:59.000Z
A system for determining the composition of a multiple-component fluid and for determining linear flow comprising at least one sing-around circuit that determines the velocity of a signal in the multiple-component fluid and that is correlatable to a database for the multiple-component fluid. A system for determining flow uses two of the inventive circuits, one of which is set at an angle that is not perpendicular to the direction of flow.
Ultrasonic Fluid Quality Sensor System
Gomm, Tyler J. (Meridian, ID); Kraft, Nancy C. (Idaho Falls, ID); Phelps, Larry D. (Pocatello, ID); Taylor, Steven C. (Idaho Falls, ID)
2003-10-21T23:59:59.000Z
A system for determining the composition of a multiple-component fluid and for determining linear flow comprising at least one sing-around circuit that determines the velocity of a signal in the multiple-component fluid and that is correlatable to a database for the multiple-component fluid. A system for determining flow uses two of the inventive circuits, one of which is set at an angle that is not perpendicular to the direction of flow.
Efficient simulation of press hardening process through integrated structural and CFD analyses
Palaniswamy, Hariharasudhan [Altair, 1820 East Big Beaver Road, Troy, MI 48083 (United States); Mondalek, Pamela; Wronski, Maciek [Altair Development France, Sophia Antipolis Cedex 06903 (France); Roy, Subir [Altair, 1820 East Big Beaver Road, Troy, MI 48083 (France)
2013-12-16T23:59:59.000Z
Press hardened steel parts are being increasingly used in automotive structures for their higher strength to meet safety standards while reducing vehicle weight to improve fuel consumption. However, manufacturing of sheet metal parts by press hardening process to achieve desired properties is extremely challenging as it involves complex interaction of plastic deformation, metallurgical change, thermal distribution, and fluid flow. Numerical simulation is critical for successful design of the process and to understand the interaction among the numerous process parameters to control the press hardening process in order to consistently achieve desired part properties. Until now there has been no integrated commercial software solution that can efficiently model the complete process from forming of the blank, heat transfer between the blank and tool, microstructure evolution in the blank, heat loss from tool to the fluid that flows through water channels in the tools. In this study, a numerical solution based on Altair HyperWorks® product suite involving RADIOSS®, a non-linear finite element based structural analysis solver and AcuSolve®, an incompressible fluid flow solver based on Galerkin Least Square Finite Element Method have been utilized to develop an efficient solution for complete press hardening process design and analysis. RADIOSS is used to handle the plastic deformation, heat transfer between the blank and tool, and microstructure evolution in the blank during cooling. While AcuSolve is used to efficiently model heat loss from tool to the fluid that flows through water channels in the tools. The approach is demonstrated through some case studies.
, interactions of fluids with solid boundaries, with gases, or with membranes (opening on a vast topic might want to experiment with turbulence, or with fluid energy devices, like hydrogen fuel cells or basic Stirling engines. There are so few fluid dynamics labs in the world that meaningful and unique
Bigelow, Stephen
CSE IGERTCOMPUTATIONAL SCIENCE AND ENGINEERING IGERT QUARTERLy NEwSLETTER Simulations of a two-component fluid (left) using a phase field model with dynamic adaptive mesh refinement (right). Hector Ceniceros patterns when a less viscous fluid (dyed water in the image) is injected into a more viscous fluid (clear
Causal dissipative hydrodynamics for QGP fluid in 2+1 dimensions
A. K. Chaudhuri
2007-08-01T23:59:59.000Z
In 2nd order causal dissipative theory, space-time evolution of QGP fluid is studied in 2+1 dimensions. Relaxation equations for shear stress tensors are solved simultaneously with the energy-momentum conservation equations. Comparison of evolution of ideal and viscous QGP fluid, initialized under the same conditions, e.g. same equilibration time, energy density and velocity profile, indicate that in a viscous dynamics, energy density or temperature of the fluid evolve slowly, than in an ideal fluid. Cooling gets slower as viscosity increases. Transverse expansion also increases in a viscous dynamics. For the first time we have also studied elliptic flow of 'quarks' in causal viscous dynamics. It is shown that elliptic flow of quarks saturates due to non-equilibrium correction to equilibrium distribution function, and can not be mimicked by an ideal hydrodynamics.
Two fluid anisotropic dark energy models in a scale invariant theory
Tripathy, S K; Sahoo, P K
2015-01-01T23:59:59.000Z
We have investigated some anisotropic dark energy models in a simple scale invariant theory of gravity. The anisotropic nature of the universe is considered through a spatially homogeneous and anisotropic Bianchi type $V$ space-time. The matter field is considered to be composed of two non interacting fluids namely the usual bulk viscous fluid and that of the dark energy fluid. Pressure anisotropy is considered along different spatial directions. From the constructed cosmological models, we found a dynamic pressure anisotropy which continues along with the cosmic expansion. The models are found to be mostly dominated by phantom behaviour. The presence of bulk viscous fluid does not affect substantially the general nature of the cosmic dynamics. The scale invariant theory of gravity is found to have a dominant role in the cosmic dynamics and help the de Sitter universe to exit from a catastrophic situation.
G. Salesi
2009-06-23T23:59:59.000Z
Starting from the Pauli current we obtain the decomposition of the non-relativistic local velocity in two parts: one parallel and the other orthogonal to the momentum. The former is recognized to be the ``classical'' part, that is the velocity of the center-of-mass, and the latter the ``quantum'' one, that is the velocity of the motion in the center-of-mass frame (namely, the internal ``spin motion'' or {\\em Zitterbewegung}). Inserting the complete expression of the velocity into the kinetic energy term of the classical non-relativistic (i.e., Newtonian) Lagrangian, we straightforwardly derive the so-called ``quantum potential'' associated to the Madelung fluid. In such a way, the quantum mechanical behaviour of particles appears to be strictly correlated to the existence of spin and Zitterbewegung.
Vajda, Sandor
BE436 FUNDAMENTALS OF FLUID MECHANICS (Spring 2014) Fluid mechanics is the study of how and why fluids move. The behavior of fluids plays a fundamental role in the function of living biological, and microfluidic devices. Course info: We will examine all of the usual topics in fluid mechanics. This course
Fluid inflation with brane correction
Ratbay Myrzakulov; Lorenzo Sebastiani
2014-11-03T23:59:59.000Z
In this paper, we have investigated the possibility to have inflation from inhomogeneous viscous fluids by taking into account the brane correction coming from string-inspired five dimensional Einsten's gravity. We have realized several kinds of viable solutions for early-time acceleration. At the end of inflation, the classical Einstein's gravity is recovered and fluids produce decelerated expansion.
Fluid jet electric discharge source
Bender, Howard A. (Ripon, CA)
2006-04-25T23:59:59.000Z
A fluid jet or filament source and a pair of coaxial high voltage electrodes, in combination, comprise an electrical discharge system to produce radiation and, in particular, EUV radiation. The fluid jet source is composed of at least two serially connected reservoirs, a first reservoir into which a fluid, that can be either a liquid or a gas, can be fed at some pressure higher than atmospheric and a second reservoir maintained at a lower pressure than the first. The fluid is allowed to expand through an aperture into a high vacuum region between a pair of coaxial electrodes. This second expansion produces a narrow well-directed fluid jet whose size is dependent on the size and configuration of the apertures and the pressure used in the reservoir. At some time during the flow of the fluid filament, a high voltage pulse is applied to the electrodes to excite the fluid to form a plasma which provides the desired radiation; the wavelength of the radiation being determined by the composition of the fluid.
Experimentally Determined Interfacial Area Between Immiscible Fluids in Porous Media
Crandall, Dustin; Niessner, J; Hassanizadeh, S.M; Smith, Duane
2008-01-01T23:59:59.000Z
When multiple fluids flow through a porous medium, the interaction between the fluid interfaces can be of great importance. While this is widely recognized in practical applications, numerical models often disregard interactios between discrete fluid phases due to the computational complexity. And rightly so, for this level of detail is well beyond most extended Darcy Law relationships. A new model of two-phase flow including the interfacial area has been proposed by Hassarizadeh and Gray based upon thermodynamic principles. A version of this general equation set has been implemented by Nessner and Hassarizadeh. Many of the interfacial parameters required by this equation set have never been determined from experiments. The work presented here is a description of how the interfacial area, capillary pressure, interfacial velocity and interfacial permeability from two-phase flow experiments in porous media experiments can be used to determine the required parameters. This work, while on-going, has shown the possibility of digitizing images within translucent porous media and identifying the location and behavior of interfaces under dynamic conditions. Using the described methods experimentally derived interfacial functions to be used in larger scale simulations are currently being developed. In summary, the following conclusions can be drawn: (1) by mapping a pore-throat geometry onto an image of immiscible fluid flow, the saturation of fluids and the individual interfaces between the fluids can be identified; (2) the resulting saturation profiles of the low velocity drainage flows used in this study are well described by an invasion percolation fractal scaling; (3) the interfacial area between fluids has been observed to increase in a linear fashion during the initial invasion of the non-wetting fluid; and (4) the average capillary pressure within the entire cell and representative elemental volumes were observed to plateau after a small portion of the volume was invaded.
L3:THM.CFD.P6.01 Report: Newton-Krylov Based P2 Projection Solver for Fluid Flows
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmospheric Optical Depth7-1D: Vegetation ProposedUsingFunInfraredJeffersonJonathanMultimaterial2 J.N. Shadid, T.M. Smith, R.P.3 Mark1
Landers, Robert G.
Fluid Systems QUESTION 1 For the system in Figure 1.1, the pipe is circular and has length L the system dynamics. A1 pa pa A2 pa k2, 2 k3, 3 k1, 1 wi(t) pipe Figure 1.1 #12;Fluid Systems 2 QUESTION 2 For the system in Figure 2.1, the pipe has length L and area Ap. Half way along the pipe is a flexible container
Inserting Group Variables into Fluid Mechanics
R. Jackiw
2004-10-28T23:59:59.000Z
A fluid, like a quark-gluon plasma, may possess degrees of freedom indexed by a group variable, which retains its identity even in the fluid/continuum description. Conventional Eulerian fluid mechanics is extended to encompass this possibility.
Finite element simulation of electrorheological fluids
Rhyou, Chanryeol, 1973-
2005-01-01T23:59:59.000Z
Electrorheological (ER) fluids change their flow properties dramatically when an electric field is applied. These fluids are usually composed of dispersions of polarizable particles in an insulating base fluid or composed ...
McKay, M.D.; Sweeney, C.E.; Spangler, B.S. Jr.
1993-11-30T23:59:59.000Z
A flow meter and temperature measuring device are described comprising a tube with a body centered therein for restricting flow and a sleeve at the upper end of the tube to carry several channels formed longitudinally in the sleeve to the appropriate axial location where they penetrate the tube to allow pressure measurements and temperature measurements with thermocouples. The high pressure measurement is made using a channel penetrating the tube away from the body and the low pressure measurement is made at a location at the widest part of the body. An end plug seals the end of the device and holes at its upper end allow fluid to pass from the interior of the tube into a plenum. The channels are made by cutting grooves in the sleeve, the grooves widened at the surface of the sleeve and then a strip of sleeve material is welded to the grooves closing the channels. Preferably the sleeve is packed with powdered graphite before cutting the grooves and welding the strips. 7 figures.
McKay, Mark D. (1426 Socastee Dr., North Augusta, SC 29841); Sweeney, Chad E. (3600 Westhampton Dr., Martinez, GA 30907-3036); Spangler, Jr., B. Samuel (2715 Margate Dr., Augusta, GA 30909)
1993-01-01T23:59:59.000Z
A flow meter and temperature measuring device comprising a tube with a body centered therein for restricting flow and a sleeve at the upper end of the tube to carry several channels formed longitudinally in the sleeve to the appropriate axial location where they penetrate the tube to allow pressure measurements and temperature measurements with thermocouples. The high pressure measurement is made using a channel penetrating the tube away from the body and the low pressure measurement is made at a location at the widest part of the body. An end plug seals the end of the device and holes at its upper end allow fluid to pass from the interior of the tube into a plenum. The channels are made by cutting grooves in the sleeve, the grooves widened at the surface of the sleeve and then a strip of sleeve material is welded to the grooves closing the channels. Preferably the sleeve is packed with powdered graphite before cutting the grooves and welding the strips.