Powered by Deep Web Technologies
Note: This page contains sample records for the topic "mesoscale convective systems" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


1

Posters Mesoscale Simulations of Convective Systems with Data...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

7 Posters Mesoscale Simulations of Convective Systems with Data Assimilation During June 1993 in the Southern Great Plains J. Dudhia Mesoscale and Microscale Meteorology Division...

2

Structures and Dynamics of Quasi-2D Mesoscale Convective Systems  

Science Journals Connector (OSTI)

Recently, three distinct archetypes for midlatitude linear mesoscale convective systems (MCSs) have been identified. This article focuses on the fundamentals of two of these archetypes: convective lines with trailing stratiform (TS) precipitation ...

Matthew D. Parker; Richard H. Johnson

2004-03-01T23:59:59.000Z

3

Mesoscale Convective Systems in Relation to African and Tropical Easterly Jets  

Science Journals Connector (OSTI)

This paper documents the interaction processes between mesoscale convective systems (MCS), the tropical easterly jet (TEJ), and the African easterly jet (AEJ) over West Africa during the monsoon peak of 2006 observed during the African Monsoon ...

L. Besson; Y. Lemaître

2014-09-01T23:59:59.000Z

4

The effect of shear on heat budgets in a simulated Mesoscale Convective System  

E-Print Network [OSTI]

The evolution and structure of simulated Mesoscale Convective Systems (MCS) were examined using the Collaborative Model for Multiscale Atmospheric Simulations. Three numerical simulations were performed, with the amount of vertical wind shear...

Shaw, Justin David

2000-01-01T23:59:59.000Z

5

Analysis of Strengthening and Dissipating Mesoscale Convective Systems Propagating off the West African Coast  

Science Journals Connector (OSTI)

A large number of Atlantic tropical depressions are generated in the eastern basin in relation to the African easterly wave (AEW) and embedded mesoscale convective systems (MCSs) coming from the African continent. In this paper, the structures of ...

Abdou L. Dieng; Laurence Eymard; Saidou M. Sall; Alban Lazar; Marion Leduc-Leballeur

2014-12-01T23:59:59.000Z

6

The evolution of total lightning and radar reflectivity characteristics of two mesoscale convective systems over Houston, Texas  

E-Print Network [OSTI]

Two mesoscale convective systems (MCSs) passed over the Houston Lightning Detection and Ranging (LDAR) network on 31 October 2005 and 21 April 2006. As the MCSs traverse the LDAR network, the systems slowly mature with a weakening convective line...

Hodapp, Charles Lee

2009-05-15T23:59:59.000Z

7

Evaluation of Ensemble Configurations for the Analysis and Prediction of Heavy-Rain-Producing Mesoscale Convective Systems  

Science Journals Connector (OSTI)

This study investigates probabilistic forecasts made using different convection-allowing ensemble configurations for a three-day period in June 2010 when numerous heavy-rain-producing mesoscale convective systems (MCSs) occurred in the United ...

Russ S. Schumacher; Adam J. Clark

2014-11-01T23:59:59.000Z

8

Evaluation of mesoscale convective systems in South America using multiple satellite products and an objectbased approach  

E-Print Network [OSTI]

Evaluation of mesoscale convective systems in South America using multiple satellite products­2003 in the La Plata river basin, southeastern South America, were analyzed with the Contiguous Rain Area (CRA; Salby and Callaghan, 1997]. However, in South America, few studies have assessed the validity

Ebert, Beth

9

Radar, satellite, and lightning characteristics of select mesoscale convective systems in Texas  

E-Print Network [OSTI]

This study compares radar data from the League City, Texas WSR-88D and cloud-to-ground (CG) lightning data for a set of eight mesoscale convective systems (MCSs) which occur at various stages of development along the upper Texas Gulf Coast. Vertical...

Toracinta, Ernest Richard

2012-06-07T23:59:59.000Z

10

Mesoscale Convective Systems and Their Synoptic-scale Environment in Finland  

Science Journals Connector (OSTI)

The environments which high-latitude intense and non-intense mesoscale convective systems (iMCSs and niMCSs) and smaller thunderstorm clusters (subMCS) develop in were studied using proximity soundings. Eight-year MCS statistics were created by ...

ARI-JUHANI PUNKKA; MARJA BISTER

11

Momentum transport processes in the stratiform regions of mesoscale convective systems over the western Pacific warm pool  

E-Print Network [OSTI]

Momentum transport by the stratiform components of mesoscale convective systems (MCSs) during the Tropical Ocean–Global Atmosphere Coupled Ocean–Atmosphere Response Experiment in December 1992 is investigated using a ...

Mechem, David B.; Chen, Shuyi S.; Houze, Robert A. Jr.

2006-04-01T23:59:59.000Z

12

A Statistical Analysis of Characteristics of Mesoscale Convective System Mountain Initiation Location Clusters in the Arkansas-Red River Basin  

E-Print Network [OSTI]

A Statistical Analysis of Characteristics of Mesoscale Convective System Mountain Initiation Location Clusters in the Arkansas-Red River Basin By Elisabeth F. Callen Submitted to the graduate degree program in Geography and the Graduate... ____________________________________ David Mechem Date Defended: November 9, 2012 ii The Thesis Committee for Elisabeth F. Callen certifies that this is the approved version of the following thesis: A Statistical Analysis of Characteristics of Mesoscale Convective...

Callen, Elisabeth F.

2012-12-31T23:59:59.000Z

13

Ensemble Kalman Filter Analyses and Forecasts of a Severe Mesoscale Convective System Using Different Choices of Microphysics Schemes  

Science Journals Connector (OSTI)

A Weather Research and Forecasting Model (WRF)-based ensemble data assimilation system is used to produce storm-scale analyses and forecasts of the 4–5 July 2003 severe mesoscale convective system (MCS) over Indiana and Ohio, which produced ...

Dustan M. Wheatley; Nusrat Yussouf; David J. Stensrud

2014-09-01T23:59:59.000Z

14

October 1986 R. H. Johnson 721 Lower-Tropospheric Warming and Drying in Tropical Mesoscale Convective Systems  

E-Print Network [OSTI]

October 1986 R. H. Johnson 721 Lower-Tropospheric Warming and Drying in Tropical Mesoscale Convective Systems: Implications for the Problem of Cumulus Parameterization By Richard H. Johnson Department beneath the stratiform com- ponents of these systems (Houze, 1977; Zipser, 1977; Johnson and Kriete, 1982

Johnson, Richard H.

15

The convective structures associated with cloud-to-ground lightning in TOGA COARE Mesoscale Convective Systems  

E-Print Network [OSTI]

indicate a pronounced difference between lightning producing and non-lightning producing cells. Lightning producing convective cells have higher radar reflectivity in the 5.0- 8.0 km layer, and a slower decrease with height, both observations indicating...

Restivo, Michael Edward

2012-06-07T23:59:59.000Z

16

On the effect of the steady-state approximation in time-space composite studies of mesoscale convective systems  

E-Print Network [OSTI]

ON THE EFFECT OF THE STRA 'Y-STATE APPROXIMATION IN TIME-SPACE COMPOSITE STUDIES OF MESOSCALE CONVECTIVE SYSTEMS A Thesis KEVIN MORGAN MATTISON Subnitted to the Office of Graduate Studies of Texas A&M University in partial fulfillnent... of the requirements for the degree of MASTER OF SCIENCE Decenber 1992 Major Subject: Meteorology ON THE EFFECT OF THE STEADY-STATE APPROXINATIOH IN TIME-SPACE COMPOSITE STUDIES OF NESOSCALE COHVECTIVE SYSTENS A Thesis KEVIN MORGAN NATTISOH Approved as to style...

Mattison, Kevin Morgan

2012-06-07T23:59:59.000Z

17

Observational Analysis of the Predictability of Mesoscale Convective Systems ISRAEL L. JIRAK AND WILLIAM R. COTTON  

E-Print Network [OSTI]

AND WILLIAM R. COTTON Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado merge into a large, long-lived organized convective system (Cotton and Anthes 1989). Thus, forecasting

18

The kinematic and cloud-to-ground lightning structure of the 9-10, June 1998 Red River Mesoscale Convective System  

E-Print Network [OSTI]

An investigation of the kinematic and electrical properties of the 9-10 June, 1998 Red River Mesoscale Convective System (MCS), as observed by the NOAA P3 Tail Radar and the National Lightning Detection Network, is presented. This system exhibits...

Santarpia, Joshua

2012-06-07T23:59:59.000Z

19

Mesoscale Convective Vortices in Multiscale, Idealized Simulations: Dependence on Background State, Interdependency with Moist Baroclinic Cyclones, and Comparison with BAMEX Observations  

Science Journals Connector (OSTI)

A set of multiscale, nested, idealized numerical simulations of mesoscale convective systems (MCSs) and mesoscale convective vortices (MCVs) was conducted. The purpose of these simulations was to investigate the dependence of MCV development and ...

Robert J. Conzemius; Michael T. Montgomery

2010-04-01T23:59:59.000Z

20

Convective cell development and propagation in a mesoscale convective complex  

E-Print Network [OSTI]

~ , National Fisheries University of Pusan Chairman of Advisory Committee: Dr ~ Kennth CD Brundidge A case study was made of the mesoscale convective complex (MCC) which occurred over southern Oklahoma and northern Texas on 27 May 1981. This storm moved... in an east-southeasterly direction and during much of its lifetime was observable by radars at Oklahoma City, OK and Stephenville, TX. It was found that the direction of cell (VIP level 3 or more reflectivity) propagation was somewhat erratic...

Ahn, Yoo-Shin

2012-06-07T23:59:59.000Z

Note: This page contains sample records for the topic "mesoscale convective systems" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

Passive microwave observations of mesoscale convective systems over the tropical Pacific Ocean  

E-Print Network [OSTI]

This paper presents high resolution passive microwave measurements obtained in the western Pacific warm pool region. These measurements represent the first comprehensive observations of convection over the tropical oceans, and were obtained from...

McGaughey, Gary Rae

2012-06-07T23:59:59.000Z

22

Technical Sessions Parameterization of Convective Clouds, Mesoscale...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

and Convective-Generated Clouds W. R. Cotton Department of Atmospheric Science Colorado State University Fort Collins, CO 80523 This presentation is a summary of research...

23

Four-Dimensional Assimilation of Multitime Wind Profiles over a Single Station and Numerical Simulation of a Mesoscale Convective  

E-Print Network [OSTI]

on the numerical simulation of the convective initiation and evolution. Besides the wind fields, the structureFour-Dimensional Assimilation of Multitime Wind Profiles over a Single Station and Numerical Simulation of a Mesoscale Convective System Observed during IHOP_2002 LEI ZHANG AND ZHAOXIA PU Department

Pu, Zhaoxia

24

Cloud-to-ground lightning characteristics of warm season Mesoscale Convection Systems in the Central United States: 1992-1993  

E-Print Network [OSTI]

, by comparing the storm systems of 1992 vs.1993, it was determined whether the CG lightning characteristics of the flood producing storm systems of 1993 were vastly different than the preceding year. Results from the climatology of the CG lightning...

Hoeth, Brian Richard

2012-06-07T23:59:59.000Z

25

Mesoscale Structure of Trade Wind Convection over Puerto Rico: Composite Observations and Numerical Simulation  

Science Journals Connector (OSTI)

We examine the mesoscale structure of the atmospheric boundary layer (ABL), low-level circulation, and trade wind convection over the sub-tropical island of Puerto Rico in mid-summer. Shallow afternoon thunder...

Mark R. Jury; Sen Chiao; Eric W. Harmsen

2009-08-01T23:59:59.000Z

26

A Climatology of Midlatitude Mesoscale Convective Vortices in the Rapid Update Cycle  

Science Journals Connector (OSTI)

Climatological characteristics of mesoscale convective vortices (MCVs) occurring in the state of Oklahoma during the late spring and summer of four years are investigated. The MCV cases are selected based on vortex detection by an objective ...

Eric P. James; Richard H. Johnson

2010-05-01T23:59:59.000Z

27

Use of ARM observations and numerical models to determine radiative and latent heating profiles of mesoscale convective systems for general circulation models  

SciTech Connect (OSTI)

This three-year project, in cooperation with Professor Bob Houze at University of Washington, has been successfully finished as planned. Both ARM (the Atmospheric Radiation Measurement Program) data and cloud-resolving model (CRM) simulations were used to identify the water budgets of clouds observed in two international field campaigns. The research results achieved shed light on several key processes of clouds in climate change (or general circulation models), which are summarized below. 1. Revealed the effect of mineral dust on mesoscale convective systems (MCSs) Two international field campaigns near a desert and a tropical coast provided unique data to drive and evaluate CRM simulations, which are TWP-ICE (the Tropical Warm Pool International Cloud Experiment) and AMMA (the African Monsoon Multidisciplinary Analysis). Studies of the two campaign data were contrasted, revealing that much mineral dust can bring about large MCSs via ice nucleation and clouds. This result was reported as a PI presentation in the 3rd ASR Science Team meeting held in Arlington, Virginia in March 2012. A paper on the studies was published in the Journal of the Atmospheric Sciences (Zeng et al. 2013). 2. Identified the effect of convective downdrafts on ice crystal concentration Using the large-scale forcing data from TWP-ICE, ARM-SGP (the Southern Great Plains) and other field campaigns, Goddard CRM simulations were carried out in comparison with radar and satellite observations. The comparison between model and observations revealed that convective downdrafts could increase ice crystal concentration by up to three or four orders, which is a key to quantitatively represent the indirect effects of ice nuclei, a kind of aerosol, on clouds and radiation in the Tropics. This result was published in the Journal of the Atmospheric Sciences (Zeng et al. 2011) and summarized in the DOE/ASR Research Highlights Summaries (see http://www.arm.gov/science/highlights/RMjY5/view). 3. Used radar observations to evaluate model simulations In cooperation with Profs. Bob Houze at University of Washington and Steven Rutledge at Colorado State University, numerical model results were evaluated with observations from W- and C-band radars and CloudSat/TRMM satellites. These studies exhibited some shortcomings of current numerical models, such as too little of thin anvil clouds, directing the future improvement of cloud microphysics parameterization in CRMs. Two papers of Powell et al (2012) and Zeng et al. (2013), summarizing these studies, were published in the Journal of the Atmospheric Sciences. 4. Analyzed the water budgets of MCSs Using ARM data from TWP-ICE, ARM-SGP and other field campaigns, the Goddard CRM simulations were carried out to analyze the water budgets of clouds from TWP-ICE and AMMA. The simulations generated a set of datasets on clouds and radiation, which are available http://cloud.gsfc.nasa.gov/. The cloud datasets were available for modelers and other researchers aiming to improve the representation of cloud processes in multi-scale modeling frameworks, GCMs and climate models. Special datasets, such as 3D cloud distributions every six minutes for TWP-ICE, were requested and generated for ARM/ASR investigators. Data server records show that 86,206 datasets were downloaded by 120 users between April of 2010 and January of 2012. 5. MMF simulations The Goddard MMF (multi-scale modeling framework) has been improved by coupling with the Goddard Land Information System (LIS) and the Goddard Earth Observing System Model, Version 5 (GOES5). It has also been optimized on NASA HEC supercomputers and can be run over 4000 CPUs. The improved MMF with high horizontal resolution (1 x 1 degree) is currently being applied to cases covering 2005 and 2006. The results show that the spatial distribution pattern of precipitation rate is well simulated by the MMF through comparisons with satellite retrievals from the CMOPRH and GPCP data sets. In addition, the MMF results were compared with three reanalyses (MERRA, ERA-Interim and CFSR). Although the MMF tends

Tao, Wei-Kuo; Houze, Robert, A., Jr.; Zeng, Xiping

2013-03-14T23:59:59.000Z

28

Mesoscale disturbances in the tropical stratosphere excited by convection: Observations and effects on the stratospheric momentum budget  

SciTech Connect (OSTI)

The importance of the momentum flux of topographically generated mesoscale gravity waves to the extratropical middle atmosphere circulation has been well established for over a decade. Estimates of the zonal forcing due to tropical mesoscale gravity waves, however, are hampered by lack of data on their primarily convective sources. The advent of aircraft measurements over tropical convective systems now makes such estimates possible without the use of ad hoc assumptions about amplitudes and phase speeds. Aircraft measurements from NASA's 1980 Panama and 1987 STEP/Australia Missions show that convectively generated disturbances observed just above the tropopause have horizontal scales comparable to those of the underlying anvils (about 50--100 km) with peak-to-peak isentropic surface variations of about 300--400 m. Satellite imagery of tropical anvil evolution indicates a typical lifetime of about five hours. Assuming that each convective system's impact on the stratosphere can be modeled as a time-dependent [open quotes]mountain[close quotes] with the preceding spatial and time scales, the excited spectrum of gravity waves can be calculated. A suitable quasi-linear wave-mean flow interaction parameterization and satellite-derived cloud area statistics can then be used to evaluate the zonal acceleration as a function of altitude induced by gravity waves from mesoscale convective systems. The results indicate maximum westerly accelerations due to breaking mesoscale gravity waves of almost 0.4 m s[sup [minus]1]/day in the upper stratosphere (in the region of the semiannual oscillation) during September, comparable to but probably smaller than the accelerations induced by planetary-scale Kelvin waves. Calculated easterly accelerations due to breaking mesoscale gravity waves in the QBO region below 35 km are smaller, accounting for about 10% of the required zonal acceleration. 35 refs., 14 figs., 1 tab.

Pfister, L.; Scott, S.; Loewenstein, M. (NASA/Ames Research Center, Moffett Field, CA (United States)); Bowen, S. (San Jose State Univ., CA (United States)); Legg, M. (Synernet, Fremont, CA (United States))

1993-04-15T23:59:59.000Z

29

Structure and evolution of a convective band MCS  

E-Print Network [OSTI]

The structure and evolution of the synoptic, mesoscale, and lightning characteristics of the 5 May 1993 non-squall line Mesoscale Convective System has been described. This storm was a long-lived Mesoscale Convective Complex. Its formation...

Valdes-Manzanilla, Arturo

2012-06-07T23:59:59.000Z

30

Vertical Structure of Convective Systems during NAME 2004  

Science Journals Connector (OSTI)

This study describes the vertical structure of mesoscale convective systems (MCSs) that characterized the 2004 North American monsoon utilizing observations from a 2875-MHz (S band) profiler and a dual-polarimetric scanning Doppler radar. Both ...

David G. Lerach; Steven A. Rutledge; Christopher R. Williams; Robert Cifelli

2010-05-01T23:59:59.000Z

31

Parameterized Mesoscale Forcing Mechanisms for Initiating Numerically Simulated Isolated Multicellular Convection  

E-Print Network [OSTI]

Multicellular Convection ADRIAN M. LOFTUS* School of Meteorology, University of Oklahoma, Norman, Oklahoma DANIEL B. WEBER Center for Analysis and Prediction of Storms, University of Oklahoma, Norman, Oklahoma CHARLES A. DOSWELL III Cooperative Institute for Mesoscale Meteorological Studies, University of Oklahoma

Doswell III, Charles A.

32

The Tilt of the Leading Edge of Mesoscale Tropical Convective Lines  

Science Journals Connector (OSTI)

The tilt with height of the leading edge of seven mesoscale convective lines in GATE is determined by two independent methods. When averaged over time and along the line axis, the tilt is found to he surprisingly shallow, between 20 and 35 ...

M. A. LeMone; G. M. Barnes; E. J. Szoke; E. J. Zipser

1984-03-01T23:59:59.000Z

33

Numerical Simulation of the Meso-? Scale Structure and Evolution of the 1977 Johnstown Flood. Part II: Inertially Stable Warm-Core Vortex and the Mesoscale Convective Complex  

Science Journals Connector (OSTI)

A mesoscale warm-core vortex associated with the mesoscale convective complex (MCC) that produced the 1977 Johnstown flood is examined using a three-dimensional nested-grid model simulation of the flood episode. In the simulation, the vortex ...

Da-Lin Zhang; J. Michael Fritsch

1987-09-01T23:59:59.000Z

34

Use of ARM observations and numerical models to determine radiative and latent heating profiles of mesoscale convective systems for general circulation models  

SciTech Connect (OSTI)

We examined cloud radar data in monsoon climates, using cloud radars at Darwin in the Australian monsoon, on a ship in the Bay of Bengal in the South Asian monsoon, and at Niamey in the West African monsoon. We followed on with a more in-depth study of the continental MCSs over West Africa. We investigated whether the West African anvil clouds connected with squall line MCSs passing over the Niamey ARM site could be simulated in a numerical model by comparing the observed anvil clouds to anvil structures generated by the Weather Research and Forecasting (WRF) mesoscale model at high resolution using six different ice-phase microphysical schemes. We carried out further simulations with a cloud-resolving model forced by sounding network budgets over the Niamey region and over the northern Australian region. We have devoted some of the effort of this project to examining how well satellite data can determine the global breadth of the anvil cloud measurements obtained at the ARM ground sites. We next considered whether satellite data could be objectively analyzed to so that their large global measurement sets can be systematically related to the ARM measurements. Further differences were detailed between the land and ocean MCS anvil clouds by examining the interior structure of the anvils with the satellite-detected the CloudSat Cloud Profiling Radar (CPR). The satellite survey of anvil clouds in the Indo-Pacific region was continued to determine the role of MCSs in producing the cloud pattern associated with the MJO.

Houze, Jr., Robert A. [University of Washington Dept. of Atmospheric Sciences

2013-11-13T23:59:59.000Z

35

Impact of Resolution on Simulation of Closed Mesoscale Cellular Convection Identified by Dynamically Guided Watershed Segmentation  

SciTech Connect (OSTI)

Organized mesoscale cellular convection (MCC) is a common feature of marine stratocumulus that forms in response to a balance between mesoscale dynamics and smaller scale processes such as cloud radiative cooling and microphysics. We use the Weather Research and Forecasting model with chemistry (WRF-Chem) and fully coupled cloud-aerosol interactions to simulate marine low clouds during the VOCALS-REx campaign over the southeast Pacific. A suite of experiments with 3- and 9-km grid spacing indicates resolution-dependent behavior. The simulations with finer grid spacing have smaller liquid water paths and cloud fractions, while cloud tops are higher. The observed diurnal cycle is reasonably well simulated. To isolate organized MCC characteristics we develop a new automated method, which uses a variation of the watershed segmentation technique that combines the detection of cloud boundaries with a test for coincident vertical velocity characteristics. This ensures that the detected cloud fields are dynamically consistent for closed MCC, the most common MCC type over the VOCALS-REx region. We demonstrate that the 3-km simulation is able to reproduce the scaling between horizontal cell size and boundary layer height seen in satellite observations. However, the 9-km simulation is unable to resolve smaller circulations corresponding to shallower boundary layers, instead producing invariant MCC horizontal scale for all simulated boundary layers depths. The results imply that climate models with grid spacing of roughly 3 km or smaller may be needed to properly simulate the MCC structure in the marine stratocumulus regions.

Martini, Matus; Gustafson, William I.; Yang, Qing; Xiao, Heng

2014-11-27T23:59:59.000Z

36

A numerical study of mesoscale convection in a rotating tropical atmosphere  

E-Print Network [OSTI]

similar to the profile of a tropical disturbance. The meso-p forcing of convection consisted of' seven temperature perturbations con- fined below 2. 4 km at intervals of 8 km out to 60 km. The meso-9 forcing of convection comprised of a cosine thermal... perturbation field out to 75 km. Two different classes of simulations were performed. The first part explored how background vorticity affects convection generated by meso-7 and meso-9 forcing. The second part investigated how meso-9 forcing of convection...

Fitzpatrick, Patrick James

1992-01-01T23:59:59.000Z

37

Aircraft Observations of Convective Systems in the Indian Ocean [EVS Event]  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Aircraft Observations of Convective Systems in the Indian Ocean Aircraft Observations of Convective Systems in the Indian Ocean August 23, 2013 Speaker: Bradley Nicholas Guy National Research Council Postdoctoral Fellow NOAA National Severe Storms Laboratory Date: Friday, August 23, 2013 Time: 11:00 a.m. Location: Argonne National Laboratory TCS Building 240 Room 4301 In the DYNAMO (Dynamics of the Madden-Julian Oscillation) field experiment, a large number of measurement platforms were deployed to study environmental and convective cloud system characteristics of the Madden-Julian Oscillation (MJO) initiation region in the Indian Ocean. A mobile platform, the NOAA P-3 instrumented aircraft, sampled intense convective cloud systems, along with the surrounding environment. This presentation will explore the characteristics of mesoscale convective

38

Cloud shading retrieval and assimilation in a satellite-model coupled mesoscale analysis system  

SciTech Connect (OSTI)

A retrieval-assimilation method has been developed as a quantitative means to exploit the information in satellite imagery regarding shading of the ground by clouds, as applied to mesoscale weather analysis. Cloud radiative parameters are retrieved from satellite visible image data and used, along with parameters computed by a numerical model, to control the model's computation of downward radiative fluxes at the ground. These fluxes influence the analysis of ground surface temperatures under clouds. The method is part of a satellite-model coupled four-dimensional analysis system that merges information from visible image data in cloudy areas with infrared sounder data in clear areas, where retrievals of surface temperatures and water vapor concentrations are assimilated. The substantial impact of shading on boundary-layer development and mesoscale circulations was demonstrated in simulations, and the value of assimilating shading retrievals was demonstrated with a case study and with a simulated analysis that included the effects of several potential sources of error. The case study was performed in the northwestern Texas area, where convective cloud development was influenced by the shading effects of a persistent region of stratiform cloud cover. Analyses that included shading retrieval assimilation had consistently smaller shelter-height temperature errors than analyses without shading retrievals. When clear-area surface temperature retrievals from sounder data were analyzed along with cloudy-area shading retrievals, the contrast in heating between the shaded and clear parts of the domain led to large variations in analyzed boundary-layer depths and had a modest impact on analyzed wind flow. The analyzed locations of upward vertical motion corresponded roughly to areas of convective cloud development observed in satellite imagery. 29 refs., 17 figs., 2 tabs.

Lipton, A.E. (Phillips Lab., Hanscom AFB, MA (United States))

1993-11-01T23:59:59.000Z

39

Characterizing and Optimizing Precipitation Forecasts from a Convection-Permitting Ensemble Initialized by a Mesoscale Ensemble Kalman Filter  

Science Journals Connector (OSTI)

Convection-permitting Weather Research and Forecasting (WRF) Model forecasts with 3-km horizontal grid spacing were produced for a 50-member ensemble over a domain spanning three-quarters of the contiguous United States between 25 May and 25 June ...

Craig S. Schwartz; Glen S. Romine; Kathryn R. Smith; Morris L. Weisman

2014-12-01T23:59:59.000Z

40

Evolution of cloud-to-ground lightning characteristics within the convective region of a midlatitude squall line  

E-Print Network [OSTI]

has been examined over a period of 49 minutes. Lightning data from the National Severe Storms Laboratory lightning detection network combined with seven dual-Doppler analyses provided a unique dataset in which to study this Mesoscale Convective System...

Billingsley, David Brian

2012-06-07T23:59:59.000Z

Note: This page contains sample records for the topic "mesoscale convective systems" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

Representing Forecast Error in a Convection-Permitting Ensemble System  

Science Journals Connector (OSTI)

Ensembles provide an opportunity to greatly improve short-term prediction of local weather hazards, yet generating reliable predictions remain a significant challenge. In particular, convection-permitting ensemble forecast systems (CPEFSs) have ...

Glen S. Romine; Craig S. Schwartz; Judith Berner; Kathryn R. Fossell; Chris Snyder; Jeff L. Anderson; Morris L. Weisman

2014-12-01T23:59:59.000Z

42

Toward the Long-range Prediction of Severe Convective Windstorms  

E-Print Network [OSTI]

thunderstorm systems (or mesoscale convective system (MCS)), cause major disruption to society, including widespread power outages, tree and structural damage, and transportation accidents that affect multi- state � Left five million without power � Traveled 700 miles in 12 hours #12;June 2012 Derecho Overview http

Kuligowski, Bob

43

Vertical profiles of radar reflectivity of convective cells in tropical and mid-latitude mesoscale convective systems  

E-Print Network [OSTI]

of tropical oceanic and tropical continental MCSs during the monsoon wet seasons of 1987/1988 and 1988/1989. The atmospheric structure, particularly the CAPE and low level vertical wind shear for all the MCS events studied is analyzed to help... lectivity, at a height of 1. 9 km, of the 68 72 2 December 1988 tropical monsoon case at 0542 LT . . 74 36 37 38 As in Fig. 35, except at 0609 LT Time series of zonal wind and CAPE at Darwin during the 1988/1989 monsoon wet season. Contour plot...

Lutz, Kurt Reed

2012-06-07T23:59:59.000Z

44

Equilibrium Structure of a Triblock Copolymer System Revealed by Mesoscale Simulation and Neutron Scattering  

SciTech Connect (OSTI)

We have performed both mesoscale simulations and neutron scattering experiments on Pluronic L62, a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock copolymer system in aqueous solution. The influence of simulation variables such PEO/PPO block ratio, interaction parameters, and coarse-graining methods is extensively investigated by covering all permutations of parameters found in the literatures. Upon increasing the polymer weight fraction from 50 wt% to 90 wt%, the equilibrium structure of the isotropic, reverse micellar, bicontinuous, worm-like micelle network, and lamellar phases are respectively predicted from the simulation depending on the choices of simulation parameters. Small angle neutron scattering (SANS) measurements show that the same polymer systems exhibit the spherical micellar, lamellar, and reverse micellar phases with the increase of the copolymer concentration at room temperature. Detailed structural analysis and comparison with simulations suggest that one of the simulation parameter sets can provide reasonable agreement with the experimentally observed structures.

Do, Changwoo [ORNL] [ORNL; Chen, Wei-Ren [ORNL] [ORNL; Hong, Kunlun [ORNL] [ORNL; Smith, Gregory Scott [ORNL] [ORNL

2013-01-01T23:59:59.000Z

45

Regional Contrast of Mesoscale Convective System Structure prior to and during Monsoon Onset across South America  

E-Print Network [OSTI]

South America THOMAS M. RICKENBACH, ROSANA NIETO-FERREIRA, AND RICHARD P. BARNHILL* Department across tropical and subtropical South America. The approach is to contrast regional differences tropical South America has the characteristic summertime maximum of a monsoon climate (Kousky 1988; Horel

Nesbitt, Steve

46

Application of the 85 GHz ice scattering signature to a global study of mesoscale convective systems  

E-Print Network [OSTI]

. . . . . . 90 LIST OF FIGURES Figure Page 24 hour coverage of one SSM/I. Areas in black receive two passes, areas in gray, one, and areas in white, none (Berg and Avery 1995) . . Cross section of a Wisconsin squall line (Spencer et al. 1989...-based tropical rainfall climatology. Seasonal variation in the OLR contours represents the migration of cloudiness between the Northern and Southern Hemispheres. Wolter and Hastenrath (1989), Mitchell and Wallace (1992), and Wang (1994) provide further...

Devlin, Karen Irene

2012-06-07T23:59:59.000Z

47

Transient luminous events above two mesoscale convective systems: Charge moment change analysis  

E-Print Network [OSTI]

in a cloudtoground (CG) lightning flash [Pasko et al., 1996, 1997; Williams, 2001; Pasko, 2010]. Related to sprites] Charge moment change (DMQ) data were examined for 41 positive cloudtoground (+CG) lightning discharges afterward. Threedimensional lightning mapping data provided positions for the incloud components

Rutledge, Steven

48

Charge rearrangement by sprites over a north Texas mesoscale convective system  

E-Print Network [OSTI]

is called a "K-change" when it is observed in a lightning flash. Citation: Hager, W. W., R. G. Sonnenfeld, W of the sprites. Data from the National Lightning Detection Network (NLDN) show that each sprite was preceded] that sprites were often preceded by large, positive cloud-to-ground lightning strokes (+CGs). Previously

Cummer, Steven A.

49

A comparison of tropical mesoscale convective systems in El Nino and La Nina  

E-Print Network [OSTI]

the two years tend to follow these patterns. There was a greater number of MCSs in the Central Pacific and East Pacific in the El Nino year and fewer MCSs in the Maritime Continent. The area distributions and median intensities of MCSs were found...

Zolman, Jody Lynn

1999-01-01T23:59:59.000Z

50

Convective variability associated with a mesoscale vortex in a midlatitude squall line system  

E-Print Network [OSTI]

. . . . . . . . . . CASE DESCRIPTION. . STORM MORPHOLOGY Low Levels (surface to 1. 9 km) Mid-to-Low Levels (2. 4 to 3. 9 km). . . . . . . . Mid-to-Upper Levels (4. 4 to 8. 9 km). . . . . . Upper Levels (9. 4 km and above). . . . . . . . . . Vertical Cross... Streamline/isotachanalysisofstorm-relativewinds at1150UTCon 28 May 1985. 1152 UTC dual Doppler analysis of kinematic and reflectivity field at 1. 4 km Mean Sea Level (MSL). . 47 , . 49 20b 1152 UTC dual Doppler analysis of the storm-relative horizontal...

Hristova-Veleva, Svetla M.

1994-01-01T23:59:59.000Z

51

Coastal Wave Generation and Wave Breaking over Terrain: Two Problems in Mesoscale Wave Dynamics  

E-Print Network [OSTI]

with open circles). The resolved-scale eddy term is shown by stars (no line), with the background viscous part then being the di erence between the net resolved-scale and resolved-scale eddy parts. : : : : : : : : : : : 36 16 Schematic sea breeze system... breeze and mesoscale convective systems. Gravity wave momentum transport away from topography in particular plays an important role in the momentum budget of the atmosphere and hence the general circulation. The present study addresses two aspects...

Qian, Tingting

2010-07-14T23:59:59.000Z

52

Toward a Mesoscale Observation Network in Southeast Asia  

Science Journals Connector (OSTI)

The current weather observation network in Southeast Asia is unable to support the accurate monitoring and prediction of the region's predominantly convective weather. Establishing a multisensor mesoscale observation network comprising automated ...

Tieh-Yong Koh; Chee-Kiat Teo

2009-04-01T23:59:59.000Z

53

Larval fish assemblages and mesoscale oceanographic structure along the Mesoamerican Barrier Reef System  

E-Print Network [OSTI]

Larval fish assemblages and mesoscale oceanographic structure along the Mesoamerican Barrier Reef Caribbean region, and contains spawning sites for a number of reef fish species. Despite this, little is known of the distribution and transport of pelagic fish larvae in the area, and basic in situ

54

Mesoscale hybrid calibration artifact  

DOE Patents [OSTI]

A mesoscale calibration artifact, also called a hybrid artifact, suitable for hybrid dimensional measurement and the method for make the artifact. The hybrid artifact has structural characteristics that make it suitable for dimensional measurement in both vision-based systems and touch-probe-based systems. The hybrid artifact employs the intersection of bulk-micromachined planes to fabricate edges that are sharp to the nanometer level and intersecting planes with crystal-lattice-defined angles.

Tran, Hy D. (Albuquerque, NM); Claudet, Andre A. (Albuquerque, NM); Oliver, Andrew D. (Waltham, MA)

2010-09-07T23:59:59.000Z

55

Natural convection heating system: off-the-wall evaluation methods  

SciTech Connect (OSTI)

One day data collection results are described for supplementary monitoring of convective air collectors coupled with rock bin storage for house heating. This particular 100% passive heated solar house in the mountains of Arizona had been extensively monitored and previously reported. New information includes the performance of collectors and storage during changeable insolation. In addition, there are evaluations of the alternative techniques for monitoring leakage of dampers on delivery registers, an empirical technique for determining the thermal contribution of direct gain features, and subjective responses of owners to the quality of convective and radiative comfort. Warm is warm, said the owner-builders. Design recommendations for future systems are made and a testing method using a bag volumeter is described. Post-occupancy evaluation is strongly recommended.

Cook, J.; Morris, W.S.

1981-01-01T23:59:59.000Z

56

Conduction and convection heat transfer in composite solar collector systems with porous absorber  

Science Journals Connector (OSTI)

Steady natural convection and conduction heat transfer has been studied in composite solar collector systems. The system consists of a glazing ... bounding wall isothermal at different temperatures, two horizontal

M. Mbaye; E. Bilgen

1993-01-01T23:59:59.000Z

57

Experimental Investigation of Natural Convection in Trombe Wall Systems  

E-Print Network [OSTI]

In this paper, experiments with a passive solar building with Trombe wall in the north cold climate are carried out and discussed, and the natural convection heat transfer process has been investigated. The relativity of the factors affecting indoor...

Chen, B.; Zhao, J.; Chen, C.; Zhuang, Z.

2006-01-01T23:59:59.000Z

58

Deep Convective Transition Characteristics in the Community Climate System Model and Changes under Global Warming  

Science Journals Connector (OSTI)

Tropical deep convective transition characteristics, including precipitation pickup, occurrence probability, and distribution tails related to extreme events, are analyzed using uncoupled and coupled versions of the Community Climate System Model (...

Sandeep Sahany; J. David Neelin; Katrina Hales; Richard B. Neale

2014-12-01T23:59:59.000Z

59

Convection Initiation along Soil Moisture Boundaries in the Southern Great Plains  

Science Journals Connector (OSTI)

Boundaries between two dissimilar air masses have been shown to be the focus region for convection initiation. One feature that has been shown to create these boundaries, as well as mesoscale circulation patterns conducive for convection, is soil ...

John D. Frye; Thomas L. Mote

2010-04-01T23:59:59.000Z

60

Sensitivity of Mesoscale Gravity Waves to the Baroclinicity of Jet-Front Systems SHUGUANG WANG AND FUQING ZHANG  

E-Print Network [OSTI]

life cycles of baroclinic waves with a high-resolution mesoscale model. Four simulations are made starting from two-dimensional baroclinic jets having different static stability and wind shear in order-dimensional spectral analysis demonstrates that these gravity waves have multiple components with different wave

Note: This page contains sample records for the topic "mesoscale convective systems" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

Mechanisms initiating deep convection over complex terrain during COPS.  

SciTech Connect (OSTI)

Precipitating convection in a mountain region of moderate topography is investigated, with particular emphasis on its initiation in response to boundary-layer and mid- and upper-tropospheric forcing mechanisms. The data used in the study are from COPS (Convective and Orographically-induced Precipitation Study) that took place in southwestern Germany and eastern France in the summer of 2007. It is found that the initiation of precipitating convection can be roughly classified as being due to either: (i) surface heating and low-level flow convergence; (ii) surface heating and moisture supply overcoming convective inhibition during latent and/or potential instability; or (iii) mid-tropospheric dynamical processes due to mesoscale convergence lines and forced mean vertical motion. These phenomena have to be adequately represented in models in order to improve quantitative precipitation forecast. Selected COPS cases are analyzed and classified into these initiation categories. Although only a subset of COPS data (mainly radiosondes, surface weather stations, radar and satellite data) are used here, it is shown that convective systems are captured in considerable detail by sensor synergy. Convergence lines were observed by Doppler radar in the location where deep convection is triggered several hours later. The results suggest that in many situations, observations of the location and timing of convergence lines will facilitate the nowcasting of convection. Further on, forecasting of the initiation of convection is significantly complicated if advection of potentially convective air masses over changing terrain features plays a major role. The passage of a frontal structure over the Vosges - Rhine valley - Black Forest orography was accompanied by an intermediate suppression of convection over the wide Rhine valley. Further downstream, an intensification of convection was observed over the Black Forest due to differential surface heating, a convergence line, and the flow generated by a gust front.

Kottmeier, C.; Kalthoff, N.; Barthlott, C.; Corsmeier, U.; Van Baelen, J.; Coulter, R.; Environmental Science Division; Inst. for Meteorology and Climate Research; Lab. de Meteorologie Physique; Inst. of Physics and Meteorology

2008-12-01T23:59:59.000Z

62

Numerical analysis of binary fluid convection in extended systems  

E-Print Network [OSTI]

arising in the primary subcritical bifurcation. The dynamics triggered by Eckhaus instability is discussed mixtures. For such mixtures, the onset of convection is via a subcritical Hopf bifurcation that gives rise of S. In the case of the experiment reported in [2] a S = -0.257 water-ethanol mixture is used. A final

Batiste, Oriol

63

Design of a novel six-axis metrology system for meso-scale nanopositioners  

E-Print Network [OSTI]

The purpose of this research is to develop the best possible means and methods of building a six axis metrology system given cost and space constraints. Six axis measurements are a crucial part of precision engineering and ...

King, Ryan N. (Ryan Nicholas)

2009-01-01T23:59:59.000Z

64

A numerical simulation of supersonic turbulent convection relating to the formation of the Solar system  

Science Journals Connector (OSTI)

......formation of the Solar system A. J. R...California Institute of Technology, Pasadena, California...from which the Solar system formed. The...giant convective cells, which span the whole layer. At cell boundaries the downflows...theory (MLT) of Solar system origin. Here......

A. J. R. Prentice; C. P. Dyt

2003-05-11T23:59:59.000Z

65

Cryogenic cooling system of HTS transformers by natural convection of subcooled liquid nitrogen  

E-Print Network [OSTI]

Cryogenic cooling system of HTS transformers by natural convection of subcooled liquid nitrogen Ho-793, South Korea Abstract Heat transfer analysis on a newly proposed cryogenic cooling system is performed, and over-load operation. One of the key techniques to realize these advantages in practice is the cryogenic

Chang, Ho-Myung

66

Adaptive Thermal Management for Portable System Batteries by Forced Convection Cooling  

E-Print Network [OSTI]

Adaptive Thermal Management for Portable System Batteries by Forced Convection Cooling Qing Xie the battery longevity increases. This is the first work that formulates the adaptive thermal management is proposed to derive the ATMB policy. Keywords-- battery system; adaptive thermal management; forced

Pedram, Massoud

67

Asymptotic Behavior of the Global Attractors to the Boussinesq System for Rayleigh-Bnard Convection  

E-Print Network [OSTI]

Asymptotic Behavior of the Global Attractors to the Boussinesq System for Rayleigh study asymptotic behavior of the global attractors to the Boussinesq sys- tem for Rayleigh-Bénard convection at large Prandtl number. In particular, we show that the global attractors to the Boussinesq

Wang, Xiaoming

68

A lattice-Boltzmann relaxation scheme for coupled convection-radiation systems  

SciTech Connect (OSTI)

The convection-radiation effects in thermal fluid flows are studied based on the lattice-Boltzmann method. Nine-velocity flow and temperature distributions are used to obtain the mass, momentum and energy equations in thermal incompressible flows by studying equivalent moment systems. The radiative heat flux in the energy equation is obtained using the discrete-ordinates solution of the radiative transfer equation. A non-oscillatory relaxation scheme is used to solve the coupled moment equations. Such schemes have the advantage of being simple and easy to implement. Numerical results are presented for two test examples on coupled convection-radiation flows in two dimensional enclosures. Detailed simulation results at different flow and radiative regimes, as well as benchmark solutions, are presented and discussed.

Banda, Mapundi K. [School of Mathematical Sciences, University of KwaZulu-Natal, Private Bag X01, Scottsville, 3209 Pietermaritzburg (South Africa)], E-mail: bandamk@ukzn.ac.za; Klar, Axel [AG Technomathematik, Fachbereich Mathematik, Technische Universitaet Kaiserslautern, 67663 Kaiserslautern (Germany)], E-mail: klar@itwm.fhg.de; Seaid, Mohammed [AG Technomathematik, Fachbereich Mathematik, Technische Universitaet Kaiserslautern, 67663 Kaiserslautern (Germany)], E-mail: seaid@mathematik.uni-kl.de

2007-10-01T23:59:59.000Z

69

Experimental and CFD Analysis of Advanced Convective Cooling Systems  

SciTech Connect (OSTI)

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).

Yassin A. Hassan; Victor M. Ugaz

2012-06-27T23:59:59.000Z

70

Regional variability of convection over northern India during the pre-monsoon season  

Science Journals Connector (OSTI)

In general, the overall differences in activity and timing of convection are a result of the influence of large-scale regional and synoptic flow patterns on the local mesoscale environment. The linkage between...

Soma Sen Roy; Shouraseni Sen Roy

2011-01-01T23:59:59.000Z

71

Mesoscale Self-Assembly of Hexagonal Plates Using Lateral Capillary Forces: Synthesis Using the "Capillary Bond"  

E-Print Network [OSTI]

Mesoscale Self-Assembly of Hexagonal Plates Using Lateral Capillary Forces: Synthesis Using examines self-assembly in a quasi-two-dimensional, mesoscale system. The system studied here involves and hydrophilic faces on the hexagonal plates led to three outcomes: (i) the extension of the strategies of self-assembly

Prentiss, Mara

72

Cold domes over the warm pool: a study of the properties of cold domes produced by mesoscale convective systems during TOGA COARE  

E-Print Network [OSTI]

in specific humidity within their cold domes. As a result, increases in the latent heat fluxes observed in the cold domes were more dependent on the increases in wind speed. Stronger cold domes (cool, dry and strong winds) were associated with squall line MCSs...

Caesar, Kathy-Ann Lois

2012-06-07T23:59:59.000Z

73

Molecule-Mimetic Chemistry and Mesoscale Self-Assembly  

E-Print Network [OSTI]

Molecule-Mimetic Chemistry and Mesoscale Self-Assembly NED B. BOWDEN, MARCUS WECK, INSUNG S. CHOI systems. We suggest that it will be possible to develop complex structures composed of "objects" that self-assemble, shape recognition, and size exclusion can be used to guide the self-assembly of these objects

Prentiss, Mara

74

Evolution of moisture convergence in a mesoscale convective complex  

E-Print Network [OSTI]

approach is very similar to that used by other researchers (Hilliger and Vonder Haar, 1979; Maddox and Vonder Haar, 1979; Fuelberg and Meyer, 1984) for satellite or radiosonde data. Their procedure also used separation intervals but because..., the dominant contributor to MC in the region of interest was the advection term (compare Figs. 14 and 15). This is contrary to the findings of other researchers (Negri and Vonder Haar, 1980; Cotton et al. , 1989), who have found that the divergence term...

Bercherer, John Phillip

1990-01-01T23:59:59.000Z

75

Meso-scale machining capabilities and issues  

SciTech Connect (OSTI)

Meso-scale manufacturing processes are bridging the gap between silicon-based MEMS processes and conventional miniature machining. These processes can fabricate two and three-dimensional parts having micron size features in traditional materials such as stainless steels, rare earth magnets, ceramics, and glass. Meso-scale processes that are currently available include, focused ion beam sputtering, micro-milling, micro-turning, excimer laser ablation, femto-second laser ablation, and micro electro discharge machining. These meso-scale processes employ subtractive machining technologies (i.e., material removal), unlike LIGA, which is an additive meso-scale process. Meso-scale processes have different material capabilities and machining performance specifications. Machining performance specifications of interest include minimum feature size, feature tolerance, feature location accuracy, surface finish, and material removal rate. Sandia National Laboratories is developing meso-scale electro-mechanical components, which require meso-scale parts that move relative to one another. The meso-scale parts fabricated by subtractive meso-scale manufacturing processes have unique tribology issues because of the variety of materials and the surface conditions produced by the different meso-scale manufacturing processes.

BENAVIDES,GILBERT L.; ADAMS,DAVID P.; YANG,PIN

2000-05-15T23:59:59.000Z

76

Quasi-Stationary Convective Systems Forming Perpendicular to, Above the Cold Pool of, Strong Bow Echoes  

E-Print Network [OSTI]

and Forecasting (WRF) model are analyzed in an attempt to understand the mechanisms responsible for initiating and maintaining the convective line. Due to coarse resolution, observational analyses are only useful for inspection of the synoptic-scale. Model...

Keene, Kelly M.

2012-10-19T23:59:59.000Z

77

Final Technical Report for "Radiative Heating Associated with Tropical Convective Cloud Systems: Its Importance at Meso and Global Scales"  

SciTech Connect (OSTI)

Heating associated with tropical cloud systems drive the global circulation. The overall research objectives of this project were to i) further quantify and understand the importance of heating in tropical convective cloud systems with innovative observational techniques, and ii) use global models to determine the large-scale circulation response to variability in tropical heating profiles, including anvil and cirrus cloud radiative forcing. The innovative observational techniques used a diversity of radar systems to create a climatology of vertical velocities associated with the full tropical convective cloud spectrum along with a dissection of the of the total heating profile of tropical cloud systems into separate components (i.e., the latent, radiative, and eddy sensible heating). These properties were used to validate storm-scale and global climate models (GCMs) and were further used to force two different types of GCMs (one with and one without interactive physics). While radiative heating was shown to account for about 20% of the total heating and did not have a strong direct response on the global circulation, the indirect response was important via its impact on convection, esp. in how radiative heating impacts the tilt of heating associated with the Madden-Julian Oscillation (MJO), a phenomenon that accounts for most tropical intraseasonal variability. This work shows strong promise in determining the sensitivity of climate models and climate processes to heating variations associated with cloud systems.

Schumacher, Courtney

2012-12-13T23:59:59.000Z

78

Mesoscale symmetries explain dynamical equivalence of food webs  

Science Journals Connector (OSTI)

A goal of complex system research is to identify the dynamical implications of network structure. While early results focused mainly on local or global structural properties, there is now growing interest in mesoscale structures that comprise more than one node but not the whole network. A central challenge is to discover under what conditions the occurrence of a specific mesoscale motif already allows conclusions on the dynamics of a network as a whole. In this paper, we investigate the dynamics of ecological food webs, complex heterogeneous networks of interacting populations. Generalizing the results of MacArthur and Sánchez-García (2009 Phys. Rev. E 80 26117), we show that certain mesoscale symmetries imply the existence of localized dynamical modes. If these modes are unstable the occurrence of the corresponding mesoscale motif implies dynamical instability regardless of the structure of the embedding network. In contrast, if the mode is stable it means that the symmetry can be exploited to reduce the number of nodes in the model, without changing the dynamics of the system. This result explains a previously observed dynamical equivalence between food webs containing a different number of species.

Helge Aufderheide; Lars Rudolf; Thilo Gross

2012-01-01T23:59:59.000Z

79

Impacts on ocean heat from transient mesoscale eddies in a hierarchy of climate models  

Science Journals Connector (OSTI)

We characterize impacts on heat in the ocean climate system from transient ocean mesoscale eddies. Our tool is a suite of centennial-scale 1990 radiatively forced numerical climate simulations from three GFDL coupled models comprising the CM2-O ...

Stephen M. Griffies; Michael Winton; Whit G. Anderson; Rusty Benson; Thomas L. Delworth; Carolina O. Dufour; John P. Dunne; Paul Goddard; Adele k. Morrison; Anthony Rosati; Andrew T. Wittenberg; Jianjun Yin; Rong Zhang

80

Processing of cloud condensation nuclei by collision-coalescence in a mesoscale model  

E-Print Network [OSTI]

The Naval Research Laboratory's Coupled Ocean-Atmosphere Mesoscale Prediction System (COAMPS) is employed to explore the relative importance of source, sink, and transport processes in producing an accurate forecast of the ...

Mechem, David B.; Robinson, Paul C.; Kogan, Yefim L.

2006-09-26T23:59:59.000Z

Note: This page contains sample records for the topic "mesoscale convective systems" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Mesoscale Atmospheric Dispersion, 2001, Ed. Z. Boybeyi, WIT Publications, Southampton, UK, Advances in Air Pollution, Vol 9, p. 424.  

E-Print Network [OSTI]

surface­atmosphere exchanges in mesoscale air pollution systems Devdutta S. Niyogi & Sethu Raman NorthMesoscale Atmospheric Dispersion, 2001, Ed. Z. Boybeyi, WIT Publications, Southampton, UK, Advances in Air Pollution, Vol 9, p. 424. Chapter 9 Numerical modeling of gas deposition and bi- directional

Raman, Sethu

82

Mesoscale model cloud scheme assessment using satellite observations Jean-Pierre Chaboureau, Jean-Pierre Cammas, Patrick J. Mascart, and Jean-Pierre Pinty  

E-Print Network [OSTI]

of the convective towers in the generation of synthetic BT maps. INDEX TERMS: 3329 Meteorology and Atmospheric-scale cloudiness in the model. A similar test conducted on the ice water and the liquid water paths confirms Dynamics: Mesoscale meteorology; 3360 Meteorology and Atmospheric Dynamics: Remote sensing; 3354

Chaboureau, Jean-Pierre

83

Poster Sessions J. Dudhia Mesoscale and Microscale Meteorology Division  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

J. Dudhia J. Dudhia Mesoscale and Microscale Meteorology Division National Center for Atmospheric Research Boulder, CO 80307-3000 Introduction The concept of an Integrated Data Assimilation and Sounding System (IDASS) ensures that the needs of data collection are partly determined by the requirements of an assimilating mesoscale model. Hence, the sounding strategy is geared towards allowing the model to do the best possible job in representing the atmosphere over CART sites, for example. It is not clear a priori what density of coverage or types of data are required for a good simulation. In this work, we address the problem of determining the impact of varying the density of coverage of an idea! network by purely numerical experimentation. We use one model run to provide data and another independent run to assimilate it.

84

MESOSCALE SIMULATIONS OF POWDER COMPACTION  

SciTech Connect (OSTI)

Mesoscale 3D simulations of shock compaction of metal and ceramic powders have been performed with an Eulerian hydrocode GEODYN. The approach was validated by simulating a well-characterized shock compaction experiment of a porous ductile metal. Simulation results using the Steinberg material model and handbook values for solid 2024 aluminum showed good agreement with experimental compaction curves and wave profiles. Brittle ceramic materials are not as well studied as metals, so a simple material model for solid ceramic (tungsten carbide) has been calibrated to match experimental compaction curves. Direct simulations of gas gun experiments with ceramic powders have been performed and showed good agreement with experimental data. The numerical shock wave profile has same character and thickness as that measured experimentally using VISAR. The numerical results show reshock states above the single-shock Hugoniot line as observed in experiments. We found that for good quantitative agreement with experiments 3D simulations are essential.

Lomov, Ilya; Fujino, Don; Antoun, Tarabay; Liu, Benjamin [Lawrence Livermore National Laboratory, P. O. Box 808, Livermore CA 94551 (United States)

2009-12-28T23:59:59.000Z

85

Postulated Mesoscale Quantum of Internal Friction Hysteresis  

E-Print Network [OSTI]

Evidence is provided, from yet another experiment, for the existence of a mesoscale quantum of internal friction hysteresis, having the value of the electron rest energy divided by the fine structure constant.

Randall D. Peters

2004-05-27T23:59:59.000Z

86

Oceanic mass transport by mesoscale eddies  

Science Journals Connector (OSTI)

...time-mean ocean circulation transports fluid as a conveyor belt, but fluid parcels can also be trapped and transported discretely...continuously, mesoscale eddies can trap fluid parcels within the eddy core and transport them discretely...

Zhengguang Zhang; Wei Wang; Bo Qiu

2014-07-18T23:59:59.000Z

87

Convection towers  

DOE Patents [OSTI]

Convection towers which are capable of cleaning the pollution from large quantities of air, of generating electricity, and of producing fresh water utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity, and condensers produce fresh water.

Prueitt, Melvin L. (Los Alamos, NM)

1996-01-01T23:59:59.000Z

88

Convection towers  

DOE Patents [OSTI]

Convection towers which are capable of cleaning the pollution from large quantities of air, of generating electricity, and of producing fresh water utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity, and condensers produce fresh water.

Prueitt, Melvin L. (Los Alamos, NM)

1995-01-01T23:59:59.000Z

89

Convection towers  

DOE Patents [OSTI]

Convection towers which are capable of cleaning the pollution from large quantities of air, of generating electricity, and of producing fresh water utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity, and condensers produce fresh water. 6 figs.

Prueitt, M.L.

1996-01-16T23:59:59.000Z

90

Convection towers  

DOE Patents [OSTI]

Convection towers which are capable of cleaning the pollution from large quantities of air and of generating electricity utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity. Other embodiments may also provide fresh water, and operate in an updraft mode.

Prueitt, Melvin L. (Los Alamos, NM)

1994-01-01T23:59:59.000Z

91

Benefits of a Fourth Ice Class in the Simulated Radar Reflectivities of Convective Systems Using a Bulk Microphysics Scheme  

Science Journals Connector (OSTI)

Current cloud microphysical schemes used in cloud and mesoscale models range from simple one-moment to multimoment, multiclass to explicit bin schemes. This study details the benefits of adding a fourth ice class (frozen drops/hail) to an already ...

Stephen E. Lang; Wei-Kuo Tao; Jiun-Dar Chern; Di Wu; Xiaowen Li

2014-10-01T23:59:59.000Z

92

Mesoscale Simulations of Power Compaction  

SciTech Connect (OSTI)

Mesoscale 3D simulations of metal and ceramic powder compaction in shock waves have been performed with an Eulerian hydrocode GEODYN. The approach was validated by simulating shock compaction of porous well-characterized ductile metal using Steinberg material model. Results of the simulations with handbook values for parameters of solid 2024 aluminum have good agreement with experimental compaction curves and wave profiles. Brittle ceramic materials are not so well studied as metals, so material model for ceramic (tungsten carbide) has been fitted to shock compression experiments of non-porous samples and further calibrated to match experimental compaction curves. Direct simulations of gas gun experiments with ceramic powder have been performed and showed good agreement with experimental data. Numerical shock wave profile has same character and thickness as measured with VISAR. Numerical results show reshock states above the single-shock Hugoniot line also observed in experiments. They found that to receive good quantitative agreement with experiment it is essential to perform 3D simulations.

Lomov, I; Fujino, D; Antoun, T; Liu, B

2009-08-06T23:59:59.000Z

93

Convection towers  

DOE Patents [OSTI]

Convection towers which are capable of cleaning the pollution from large quantities of air and of generating electricity utilize the evaporation of water sprayed into the towers to create strong airflows and to remove pollution from the air. Turbines in tunnels at the skirt section of the towers generate electricity. Other embodiments may also provide fresh water, and operate in an updraft mode. 5 figures.

Prueitt, M.L.

1994-02-08T23:59:59.000Z

94

Convective heater  

DOE Patents [OSTI]

A convective heater for heating fluids such as a coal slurry is constructed of a tube circuit arrangement which obtains an optimum temperature distribution to give a relatively constant slurry film temperature. The heater is constructed to divide the heating gas flow into two equal paths and the tube circuit for the slurry is arranged to provide a mixed flow configuration whereby the slurry passes through the two heating gas paths in successive co-current, counter-current and co-current flow relative to the heating gas flow. This arrangement permits the utilization of minimum surface area for a given maximum film temperature of the slurry consistent with the prevention of coke formation.

Thorogood, Robert M. (Macungie, PA)

1983-01-01T23:59:59.000Z

95

Convective heater  

DOE Patents [OSTI]

A convective heater for heating fluids such as a coal slurry is constructed of a tube circuit arrangement which obtains an optimum temperature distribution to give a relatively constant slurry film temperature. The heater is constructed to divide the heating gas flow into two equal paths and the tube circuit for the slurry is arranged to provide a mixed flow configuration whereby the slurry passes through the two heating gas paths in successive co-current, counter-current and co-current flow relative to the heating gas flow. This arrangement permits the utilization of minimum surface area for a given maximum film temperature of the slurry consistent with the prevention of coke formation.

Thorogood, Robert M. (Macungie, PA)

1986-01-01T23:59:59.000Z

96

Squall Lines and Convectively Coupled Gravity Waves in the Tropics: Why Do Most Cloud Systems Propagate Westward?  

Science Journals Connector (OSTI)

The coupling between tropical convection and zonally propagating gravity waves is assessed through Fourier analysis of high-resolution (3-hourly, 0.5°) satellite rainfall data. Results show the familiar enhancement in power along the dispersion ...

Stefan N. Tulich; George N. Kiladis

2012-10-01T23:59:59.000Z

97

ARM - Evaluation Product - Convective Vertical Velocity  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

ProductsConvective Vertical Velocity ProductsConvective Vertical Velocity Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Evaluation Product : Convective Vertical Velocity 2011.04.25 - 2011.05.23 Site(s) SGP General Description Convective processes play an important role in Earth's energy balance by distributing heat and moisture throughout the atmosphere. In particular, vertical air motions associated with these processes are inherently linked to the life cycle of these convective systems and are therefore directly tied to their energy budget. However, direct measurements of vertical air motions (e.g., in situ aircraft observations) are sparse, making it difficult to compare them with numerical model output, which relies on convective parameterization schemes that have yet to be extensively

98

Characteristics of Precipitating Convective Systems Accounting for the Summer Rainfall of Tropical and Subtropical South America  

E-Print Network [OSTI]

and Subtropical South America ULRIKE ROMATSCHKE AND ROBERT A. HOUZE JR. University of Washington, Seattle of the precipitating cloud systems that account for the summer rainfall of tropical and subtropical South America role in the meteorology, climatology, and hydrology of South America. They not only produce

Houze Jr., Robert A.

99

Tracking tropical cloud systems for the diagnosis of simulations by the weather research and forecasting (WRF) model  

SciTech Connect (OSTI)

To aid in improving model parameterizations of clouds and convection, we examine the capability of models, using explicit convection, to simulate the life cycle of tropical cloud systems in the tropical warm pool. The cloud life cycle is determined using a satellite cloud tracking algorithm (Boer and Ramanathan, J. Geophys. Res., 1997), and the statistics are compared to those of simulations using the Weather Research and Forecasting (WRF) Model. Using New York Blue, a Blue Gene/L supercomputer that is co-operated by Brookhaven and Stony Brook, simulations are run at a resolution comparable to the observations. Initial results suggest that the organization of the mesoscale convective systems is particularly sensitive to the cloud microphysics parameterization used.

Vogelmann, A.M.; Lin, W.; Cialella, A.; Luke, E. P.; Jensen, M. P.; Zhang, M. H.; Boer, E.

2010-06-27T23:59:59.000Z

100

Lagrangian study of transport and mixing in a mesoscale eddy street  

E-Print Network [OSTI]

We use dynamical systems approach and Lagrangian tools to study surface transport and mixing of water masses in a selected coastal region of the Japan Sea with moving mesoscale eddies associated with the Primorskoye Current. Lagrangian trajectories are computed for a large number of particles in an interpolated velocity field generated by a numerical regional multi-layer eddy-resolving circulation model. We compute finite-time Lyapunov exponents for a comparatively long period of time by the method developed and plot the Lyapunov synoptic map quantifying surface transport and mixing in that region. This map uncovers the striking flow structures along the coast with a mesoscale eddy street and repelling material lines. We propose new Lagrangian diagnostic tools --- the time of exit of particles off a selected box, the number of changes of the sign of zonal and meridional velocities --- to study transport and mixing by a pair of strongly interacting eddies often visible at sea-surface temperature satellite images in that region. We develop a technique to track evolution of clusters of particles, streaklines and material lines. The Lagrangian tools used allow us to reveal mesoscale eddies and their structure, to track different phases of the coastal flow, to find inhomogeneous character of transport and mixing on mesoscales and submesoscales and to quantify mixing by the values of exit times and the number of times particles wind around the eddy's center.

S. V. Prants; M. V. Budyansky; V. I. Ponomarev; M. Yu. Uleysky

2012-02-02T23:59:59.000Z

Note: This page contains sample records for the topic "mesoscale convective systems" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

Formation of mesoscale roughening in 6022-T4 Al sheets deformed in plane-strain tension  

Science Journals Connector (OSTI)

Mesoscale surface-roughening evolution in 6022-T4 Al sheets was ... are central to the formation of mesoscale surface roughening.

Y. S. Choi; H. R. Piehler; A. D. Rollett

2004-02-01T23:59:59.000Z

102

SURFACE TENSION DRIVEN CONVECTION  

E-Print Network [OSTI]

SURFACE TENSION DRIVEN CONVECTION DIJKSTRA, SENGUL, WANG INTRODUCTION LINEAR THEORY MAIN THEOREMS CONCLUDING REMARKS DYNAMIC TRANSITIONS OF SURFACE TENSION DRIVEN CONVECTION H.Dijkstra T. Sengul S. Wang #12;SURFACE TENSION DRIVEN CONVECTION DIJKSTRA, SENGUL, WANG INTRODUCTION LINEAR THEORY MAIN THEOREMS

Wang, Shouhong

103

ARM - Midlatitude Continental Convective Clouds  

DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

Convective processes play a critical role in the Earth's energy balance through the redistribution of heat and moisture in the atmosphere and their link to the hydrological cycle. Accurate representation of convective processes in numerical models is vital towards improving current and future simulations of Earths climate system. Despite improvements in computing power, current operational weather and global climate models are unable to resolve the natural temporal and spatial scales important to convective processes and therefore must turn to parameterization schemes to represent these processes. In turn, parameterization schemes in cloud-resolving models need to be evaluated for their generality and application to a variety of atmospheric conditions. Data from field campaigns with appropriate forcing descriptors have been traditionally used by modelers for evaluating and improving parameterization schemes.

Jensen, Mike; Bartholomew, Mary Jane; Genio, Anthony Del; Giangrande, Scott; Kollias, Pavlos

104

Data assimilation for stratified convection  

E-Print Network [OSTI]

We show how the 3DVAR data assimilation methodology can be used in the astrophysical context of a two-dimensional convection flow. We study the way this variational approach finds best estimates of the current state of the flow from a weighted average of model states and observations. We use numerical simulations to generate synthetic observations of a vertical two-dimensional slice of the outer part of the solar convection zone for varying noise levels and implement 3DVAR when the covariance matrices are scalar. Our simulation results demonstrate the capability of 3DVAR to produce error estimates of system states between up to tree orders of magnitude below the original noise level present in the observations. This work exemplifies the importance of applying data assimilation techniques in simulations of the stratified convection.

Svedin, Andreas; Brandenburg, Axel

2013-01-01T23:59:59.000Z

105

Rotational and divergent kinetic energy in the mesoscale model ALADIN  

E-Print Network [OSTI]

Rotational and divergent kinetic energy in the mesoscale model ALADIN By V. BLAZ ICA1 *, N. Z AGAR1 received 7 June 2012; in final form 7 March 2013) ABSTRACT Kinetic energy spectra from the mesoscale. It is shown that about 50% of kinetic energy in the free troposphere in ALADIN is divergent energy

Zagar, Nedjeljka

106

Mesoscale Processes Contributing to Extreme Rainfall in a Midlatitude Warm-Season Flash  

E-Print Network [OSTI]

for this event. However, convection-permitting simulations using the Weather Research and Forecasting (WRF) model system that was conducive to extreme local rainfall amounts. Idealized simulations of convection and that the vertical wind pro- file featuring a strong reversal of the wind shear with height is responsible for 1 #12

Johnson, Richard H.

107

Lagrangian study of transport and mixing in a mesoscale eddy street  

E-Print Network [OSTI]

We use dynamical systems approach and Lagrangian tools to study surface transport and mixing of water masses in a selected coastal region of the Japan Sea with moving mesoscale eddies associated with the Primorskoye Current. Lagrangian trajectories are computed for a large number of particles in an interpolated velocity field generated by a numerical regional multi-layer eddy-resolving circulation model. We compute finite-time Lyapunov exponents for a comparatively long period of time by the method developed and plot the Lyapunov synoptic map quantifying surface transport and mixing in that region. This map uncovers the striking flow structures along the coast with a mesoscale eddy street and repelling material lines. We propose new Lagrangian diagnostic tools --- the time of exit of particles off a selected box, the number of changes of the sign of zonal and meridional velocities --- to study transport and mixing by a pair of strongly interacting eddies often visible at sea-surface temperature satellite imag...

Prants, S V; Ponomarev, V I; Uleysky, M Yu; 10.1016/j.ocemod.2011.02.008

2012-01-01T23:59:59.000Z

108

Mesoscale Quantization and Self-Organized Stability  

E-Print Network [OSTI]

In the world of technology, one of the most important forms of friction is that of rolling friction. Yet it is one of the least studied of all the known forms of energy dissipation. In the present experiments we investigate the oscillatory free-decay of a rigid cube, whose side-length is less than the diameter of the rigid cylinder on which it rests. The resulting free-decay is one of harmonic motion with damping. The non-dissipative character of the oscillation yields to a linear differential equation; however, the damping is found to involve more than a deterministic nonlinearity. Dominated by rolling friction, the damping is sensitive to the material properties of the contact surfaces. For `clean' surfaces of glass on glass, the decay shows features of mesoscale quantization and self-organized stability.

Randall D. Peters

2005-06-16T23:59:59.000Z

109

ARM Convective Available Potential Energy (CAPE), Convective Inhibition (CIN) Product  

SciTech Connect (OSTI)

ARM soundings are used to determine Convective Available Potential Energy (CAPE), Convective Inhibition (CIN) and associated properties, using the following relationships;

Jensen, Michael

2014-04-10T23:59:59.000Z

110

ARM Convective Available Potential Energy (CAPE), Convective Inhibition (CIN) Product  

DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

ARM soundings are used to determine Convective Available Potential Energy (CAPE), Convective Inhibition (CIN) and associated properties, using the following relationships;

Jensen, Michael

111

Heat Transfer and Convection Currents  

Science Journals Connector (OSTI)

...October 1965 research-article Heat Transfer and Convection Currents D. C...convection in a medium with internal heat generation is discussed semi-quantitatively...States English United Kingdom 1966 Heat transfer and convection currents Tozer D...

1965-01-01T23:59:59.000Z

112

Satellite Observations of Mesoscale Eddy-Induced Ekman Pumping  

Science Journals Connector (OSTI)

Three mechanisms for self-induced Ekman pumping in the interiors of mesoscale ocean eddies are investigated. The first arises from the surface stress that occurs because of differences between surface wind and ocean velocities, resulting in Ekman ...

Peter Gaube; Dudley B. Chelton; Roger M. Samelson; Michael G. Schlax; Larry W. O’Neill

113

Advances in mesoscale thermal management technologies for microelectronics  

Science Journals Connector (OSTI)

This paper presents recent advances in a number of novel, high-performance cooling techniques for emerging electronics applications. Critical enabling thermal management technologies covered include microchannel transport and micropumps, jet impingement, ... Keywords: Mesoscale, Microelctronics, Thermal management

Suresh V. Garimella

2006-11-01T23:59:59.000Z

114

Life Cycle and Mesoscale Frontal Structure of an Intermountain Cyclone  

Science Journals Connector (OSTI)

High-resolution analyses and MesoWest surface observations are used to examine the life cycle and mesoscale frontal structure of the “Tax Day Storm,” an intermountain cyclone that produced the second lowest sea level pressure observed in Utah ...

Gregory L. West; W. James Steenburgh

2010-07-01T23:59:59.000Z

115

Evolution of vertical drafts and cloud-to-ground lightning within the convective region of a mesoscale convective complex  

E-Print Network [OSTI]

to ground in every 10 minute dme interval from 0600-1200 UTC for the 4 June 1985 MCC 43 24 Vertical profile of area-averaged vertical velocity for (a) west lobe froin 0905-1042 UTC, (b) east lobe from 0914-0952 UTC, and (c) east lobe from 1002-1042 UTC.... . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 25 Vertical profile of variance of the vertical velocity for (a) west lobe from 0905-1042 UTC, (b) east lobe from 0914-0952 UTC, and (c) east lobe froin 1002-1042 UTC...

Saul, Scott Henry

2012-06-07T23:59:59.000Z

116

Interpreting Temperature Strain Data from Meso-Scale Clathrate Experiments  

SciTech Connect (OSTI)

Gas hydrates are important in global climate change, carbon sequestra- tion, and seafloor stability. Currently, formation and dissociation pathways are poorly defined. We present a new approach for processing large amounts of data from meso-scale experiments, such as the LUNA distributed sensing system (DSS) in the seafloor process simulator (SPS) at Oak Ridge National Laboratory. The DSS provides a proxy for temperature measurement with a high spatial resolution allowing the heat of reaction during gas hydrate formation/dissociation to aid in locating clathrates in the vessel. The DSS fibers are placed in the sediment following an Archimedean spiral design and then the position of each sensor is solved by iterating over the arc length formula with Newtons method. The data is then gridded with 1 a natural neighbor interpolation algorithm to allow contouring of the data. The solution of the sensor locations is verified with hot and cold stimulus in known locations. An experiment was preformed with a vertically split column of sand and silt. The DSS system clearly showed hydrate forming in the sand first, then slowly creeping into the silt. Similar systems and data processing techniques could be used for monitoring of hydrates in natural environments or in any situation where a hybrid temperature/strain index is useful. Further ad- vances in fiber technology allow the fiber to be applied in any configuration and the position of each sensor to be precisely determined making practical applications easier.

Leeman, John R [ORNL; Rawn, Claudia J [ORNL; Ulrich, Shannon M [ORNL; Elwood Madden, Megan [University of Oklahoma, Norman; Phelps, Tommy Joe [ORNL

2012-01-01T23:59:59.000Z

117

Mesoscale environmental models accompanying convection in the Texas HIPLEX region / by Mark Edward Humbert  

E-Print Network [OSTI]

. The basic data were gridded using a scheme developed by Barnes(1964). The averages determined in this manner are an adequate representation of con- ditions surrounding Big Spring. The variables are presented at 850, 700, and 500 mb s1nce these levels... not be established at Big Spring since the moisture data were missing for that hour. 23-24 June 1977 Charts of radar echoes for this day are presented in Fig. 25 with those charts in the left-hand column corresponding to sounding times. Moderate rainshowers...

Humbert, Mark Edward

2012-06-07T23:59:59.000Z

118

Probabilistic Evaluation of the Dynamics and Predictability of the Mesoscale Convective Vortex of 1013 June 2003  

E-Print Network [OSTI]

National Center for Atmospheric Research,* Boulder, Colorado (Manuscript received 14 September 2005 have been linked to extreme rainfall events, such as the Johnstown, Pennsylvania, flood of 1977 (Bosart

Meng, Zhiyong

119

Solar Radiation Estimated Through Mesoscale Atmospheric Modeling over Northeast Brazil  

Science Journals Connector (OSTI)

The use of renewable energy sources like solar wind and biomass is rapidly increasing in recent years with solar radiation as a particularly abundant energy source over Northeast Brazil. A proper quantitative knowledge of the incoming solar radiation is of great importance for energy planning in Brazil serving as basis for developing future projects of photovoltaic power plants and solar energy exploitation. This work presents a methodology for mapping the incoming solar radiation at ground level for Northeast Brazil using a mesoscale atmospheric model (Regional Atmospheric Modeling System—RAMS) calibrated and validated using data from the network of automatic surface stations from the State Foundation for Meteorology and Water Resources from Ceará (Fundação Cearense de Meteorologia e Recursos Hídricos? FUNCEME). The results showed that the model exhibits systematic errors overestimating surface radiation but that after the proper statistical corrections using a relationship between the model?predicted cloud fraction the ground?level observed solar radiation and the incoming solar radiation estimated at the top of the atmosphere a correlation of 0.92 with a confidence interval of 13.5? W / m 2 is found for monthly data. Using this methodology we found an estimate for annual average incoming solar radiation over Ceará of 215? W / m 2 (maximum in October: 260? W / m 2 ).

Otacilio Leandro de Menezes Neto; Alexandre Araújo Costa; Fernando Pinto Ramalho; Paulo Henrique Santiago de Maria

2009-01-01T23:59:59.000Z

120

The influence of mesoscale eddies on shallow water acoustic propagation  

Science Journals Connector (OSTI)

Acoustic propagation measurements in 150 m depth on the Florida escarpment observe the effects of the passage of a cyclonic eddy. As the stream core of the Florida Current meanders the eddy is formed and propagates along the shelf edge. The sequence over a roughly a fortnight is as follows: ahead of the eddy warm surface water and cold bottom water are swept onto the terrace forming a steep thermocline and corresponding strong downward refracting C(z). The gradient produce intense focused RBR arrivals and the thermocline becomes a duct for internal waves to propagate shoreward. At first the internal wave energy is minimal and propagation is stable and coherent. As the internal tides attempt to propagate on shelf the sound speed field and the acoustic signals become increasingly variable. The variability reaches a crescendo as the 200 m long internal tide is blocked from propagating on to the narrower shelf and begins to break and overturn producing small?scale variability. As the eddy passes nearly iso?thermal conditions are restored along with quiescent internal wave fields and reduced signal variability. Here the effects are quantized with data from fixed?system acoustic and oceanographic measurements demonstrating that the mesoscale determines acoustic propagation conditions days in advance.

2003-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "mesoscale convective systems" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

Modeling the Atmospheric Boundary Layer Wind Response to Mesoscale Sea Surface Temperature Perturbations  

Science Journals Connector (OSTI)

The wind speed response to mesoscale SST variability is investigated over the Agulhas Return Current region of the Southern Ocean using the Weather Research and Forecasting (WRF) Model and the U.S. Navy Coupled Ocean–Atmosphere Mesoscale ...

Natalie Perlin; Simon P. de Szoeke; Dudley B. Chelton; Roger M. Samelson; Eric D. Skyllingstad; Larry W. O’Neill

2014-11-01T23:59:59.000Z

122

Mesoscale Origin of the Enhanced Cycling-Stability of the Si...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Mesoscale Origin of the Enhanced Cycling-Stability of the Si-Conductive Polymer Anode for Li-ion Batteries. Mesoscale Origin of the Enhanced Cycling-Stability of the Si-Conductive...

123

Recipes for Correcting the Impact of Effective Mesoscale Resolution on the Estimation of Extreme Winds  

Science Journals Connector (OSTI)

Extreme winds derived from simulations using mesoscale models are underestimated because of the effective spatial and temporal resolutions. This is reflected in the spectral domain as an energy deficit in the mesoscale range. The energy deficit ...

Xiaoli Guo Larsén; Søren Ott; Jake Badger; Andrea N. Hahmann; Jakob Mann

2012-03-01T23:59:59.000Z

124

The Impact of Data Assimilation Length Scales on Analysis and Prediction of Convective Storms  

Science Journals Connector (OSTI)

An idealized convective test bed for the local ensemble transform Kalman filter (LETKF) is set up to perform storm-scale data assimilation of simulated Doppler radar observations. Convective systems with lifetimes exceeding 6 h are triggered in a ...

Heiner Lange; George C. Craig

2014-10-01T23:59:59.000Z

125

Self-Assembly of Mesoscale Isomers: The Role of Pathways and Degrees of Freedom  

E-Print Network [OSTI]

Self-Assembly of Mesoscale Isomers: The Role of Pathways and Degrees of Freedom Shivendra Pandey1 geometric path sampling and a mesoscale experimental model to investigate the self-assembly of a model. Citation: Pandey S, Johnson D, Kaplan R, Klobusicky J, Menon G, et al. (2014) Self-Assembly of Mesoscale

Menon, Govind

126

Silicon Micromachined Dimensional Calibration Artifact for Mesoscale Measurement Machines  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Silicon Micromachined Dimensional Calibration Silicon Micromachined Dimensional Calibration Artifact for Mesoscale Measurement Machines 1 Silicon Micromachined Dimensional Calibration Artifact for Mesoscale Measurement Machines 2 Sandia National Laboratories PO Box 5800 Albuquerque, NM 87185 USA Hy D. Tran, PhD, PE Phone: (505)844-5417 Fax: (505)844-4372 hdtran@sandia.gov AFFIRMATION: I affirm that all information submitted as a part of, or supplemental to, this entry is a fair and accurate representation of this product. ___________________________________ Hy D. Tran Not a joint entry. Silicon Micromachined Dimensional Calibration Artifact for Mesoscale Measurement Machines The silicon hybrid artifact is an anisotropic-etched silicon standard that is used as a calibration reference artifact to calibrate vision-based and

127

ARM - Publications: Science Team Meeting Documents: Evaluation of mesoscale  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Evaluation of mesoscale model cloud simulations of the March 2000 IOP Evaluation of mesoscale model cloud simulations of the March 2000 IOP Tselioudis, George NASA/Goddard Institute for Space Studies A suite of mesoscale models was used to produce month-long runs of the March 2000 SGP IOP. The model cloud fields were evaluated against satellite and in-situ observations, using both monthly statistics of cloud properties and instantaneous cloud property distributions. It was found that compared to satellite retrievals models tend to overestimate cloud optical thickness in all dynamic regimes. The reasons for the differences in satellite and model cloud fields were investigated. Preliminary results indicate that the large model optical depths may be caused by an overestimate of cloud ice water amounts in the model simulations. Part of the differences, however,

128

Mesoscale Climatic Simulation of Surface Air Temperature Cooling by Highly  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Mesoscale Climatic Simulation of Surface Air Temperature Cooling by Highly Mesoscale Climatic Simulation of Surface Air Temperature Cooling by Highly Reflective Greenhouses in SE Spain Title Mesoscale Climatic Simulation of Surface Air Temperature Cooling by Highly Reflective Greenhouses in SE Spain Publication Type Journal Article Year of Publication 2013 Authors Campra, Pablo, and Dev Millstein Journal Environmental Science & Technology Volume 47 Issue 21 Pagination 12284 - 12290 Date Published 11/2013 ISSN 0013-936X Keywords buildings, Heat Island Group Abstract A long-term local cooling trend in surface air temperature has been monitored at the largest concentration of reflective greenhouses in the world, at the Province of Almeria, SE Spain, associated with a dramatic increase in surface albedo in the area. The availability of reliable long-term climatic field data at this site offers a unique opportunity to test the skill of mesoscale meteorological models describing and predicting the impacts of land use change on local climate. Using the Weather Research and Forecast (WRF) mesoscale model, we have run a sensitivity experiment to simulate the impact of the observed surface albedo change on monthly and annual surface air temperatures. The model output showed a mean annual cooling of 0.25 °C associated with a 0.09 albedo increase, and a reduction of 22.8 W m-2 of net incoming solar radiation at surface. Mean reduction of summer daily maximum temperatures was 0.49 °C, with the largest single-day decrease equal to 1.3 °C. WRF output was evaluated and compared with observations. A mean annual warm bias (MBE) of 0.42 °C was estimated. High correlation coefficients (R2 > 0.9) were found between modeled and observed values. This study has particular interest in the assessment of the potential for urban temperature cooling by cool roofs deployment projects, as well as in the evaluation of mesoscale climatic models performance.

129

Environmental Distinctions between Cellular and Slabular Convective Lines  

Science Journals Connector (OSTI)

The organizational mode of quasi-linear convective systems often falls within a spectrum of modes described by a line of discrete cells on one end (“cellular”) and an unbroken two-dimensional swath of ascent on the other (“slabular”). Convective ...

Richard P. James; J. Michael Fritsch; Paul M. Markowski

2005-09-01T23:59:59.000Z

130

Natural convection heat exchangers for solar water heating systems. Technical progress report, November 15, 1996--January 14, 1997  

SciTech Connect (OSTI)

The goals of this project are: (1) to develop guidelines for the design and use of thermosypohon side-arm heat exchangers in solar domestic water heating systems, and (2) to establish appropriate modeling and testing criteria for evaluating the performance of systems using this type of heat exchanger.

Davidson, J.H.

1998-06-01T23:59:59.000Z

131

MESOSCALE MODELLING OF WIND ENERGY OVER NON-HOMOGENEOUS TERRAIN  

E-Print Network [OSTI]

MESOSCALE MODELLING OF WIND ENERGY OVER NON-HOMOGENEOUS TERRAIN (ReviewArticle) Y. MAHRER.1. OBSERVATIONALAPPROACHES Evaluations of wind energy based on wind observations (usually surface winds) at well, the resolution of the wind energy pattern throughout an extended area by this methodology requires a large number

Pielke, Roger A.

132

WIND ATLAS FOR EGYPT: MEASUREMENTS, MICRO-AND MESOSCALE MODELLING  

E-Print Network [OSTI]

WIND ATLAS FOR EGYPT: MEASUREMENTS, MICRO- AND MESOSCALE MODELLING Niels G. Mortensen1 , Jens Energy Authority, Cairo, Egypt Ahmed El Sayed Yousef, Adel Mahmoud Awad, Mahmoud Abd-El Raheem Ahmed Meteorological Authority, Cairo, Egypt ABSTRACT The results of a comprehensive, 8-year wind resource assessment

133

Mesoscale predictability of an extreme warm-season precipitation event  

E-Print Network [OSTI]

. The Penn State University/NCAR Mesoscale Model version 5 (MM5) was used to conduct predictability experiments, which follow closely to the research conducted by Zhang et al. A control simulation initialized at 00Z 1 July is established over a 30-km grid...

Odins, Andrew Michael

2005-02-17T23:59:59.000Z

134

Mesoscale Waves as a Probe of Jupiter's Deep Atmosphere  

Science Journals Connector (OSTI)

Search of the Voyager images of Jupiter reveals a class of mesoscale waves occurring near the extrema of the zonal velocity profile between latitudes 30°S and 30°N. The average horizontal wavelength is 300 km, compared to an atmospheric scale ...

F. M. Flasar; P. J. Gierasch

1986-11-01T23:59:59.000Z

135

Mesoscale Science: Lessons from and Opportunities for Nanoscience  

Science Journals Connector (OSTI)

Earlier this month, I attended and spoke at a workshop of the Chemical Sciences Roundtable on mesoscale science. ... We hope that having ACS Nano to share both challenges and successes across communities will help accelerate advances by cross-fertilizing efforts and by inspiring scientists and engineers around the world. ...

Paul S. Weiss

2014-11-25T23:59:59.000Z

136

Convective Cloud Lifecycles Lunchtime seminar  

E-Print Network [OSTI]

Convective Cloud Lifecycles Lunchtime seminar 19th May 2009 Bob Plant Department of Meteorology, University of Reading, UK #12;Introduction Obtain life cycle statistics for clouds in CRM simulations Why Conclusions Convective Cloud Lifecycles ­ p.1/3 #12;Why bother? Convective Cloud Lifecycles ­ p.2/3 #12;Some

Plant, Robert

137

A soil moisture assimilation scheme using satellite-retrieved skin temperature in meso-scale weather forecast model  

Science Journals Connector (OSTI)

A thermodynamically consistent soil moisture assimilation scheme for clear sky and snow free conditions has been developed for the meso-scale modeling system in the Arctic region by using satellite-derived skin temperatures. Parallel control and sensitivity modeling experiments were designed and their results demonstrated that the assimilation scheme successfully improves the soil moistures that were deliberately perturbed initially, indicating capability of the scheme to correct bias in the soil moisture initialization. Moreover, the resultant benefit of this assimilation scheme does not only lie in the improvement of soil moisture; the skin temperature also consequently exhibits improvements in a thermodynamic consistency. A real application of the assimilation scheme with satellite-retrieved skin temperature exhibited noticeable positive impacts on the modeling simulation and weather forecast; the model obviously captured meso-scale features of soil moistures as well as the skin temperatures. The warming tendency bias in original model simulations was removed to a considerable extent by this assimilation scheme.

Jing Zhang; Xiangdong Zhang

2010-01-01T23:59:59.000Z

138

BNL | Midlatitude Continental Convective Clouds Experiment (MC3E)  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Midlatitude Continental Convective Clouds Experiment Midlatitude Continental Convective Clouds Experiment Convective processes play a critical role in the Earth's energy balance through the redistribution of heat and moisture in the atmosphere and their link to the hydrological cycle. Accurate representation of convective processes in numerical models is vital towards improving current and future simulations of Earths climate system. Despite improvements in computing power, current operational weather and global climate models are unable to resolve the natural temporal and spatial scales important to convective processes and therefore must turn to parameterization schemes to represent these processes. In turn, parameterization schemes in cloud-resolving models need to be evaluated for their generality and application to a

139

Life Cycle of a Mesoscale Circular Gust Front Observed by a C-Band Doppler Radar in West Africa  

E-Print Network [OSTI]

On 10 July 2006, during the Special Observation Period (SOP) of the African Monsoon Multidisciplinary Analysis (AMMA) campaign, a small convective system initiated over Niamey and propagated westward in the vicinity of ...

Lothon, Marie

140

Mesoscale Modeling of LX-17 Under Isentropic Compression  

SciTech Connect (OSTI)

Mesoscale simulations of LX-17 incorporating different equilibrium mixture models were used to investigate the unreacted equation-of-state (UEOS) of TATB. Candidate TATB UEOS were calculated using the equilibrium mixture models and benchmarked with mesoscale simulations of isentropic compression experiments (ICE). X-ray computed tomography (XRCT) data provided the basis for initializing the simulations with realistic microstructural details. Three equilibrium mixture models were used in this study. The single constituent with conservation equations (SCCE) model was based on a mass-fraction weighted specific volume and the conservation of mass, momentum, and energy. The single constituent equation-of-state (SCEOS) model was based on a mass-fraction weighted specific volume and the equation-of-state of the constituents. The kinetic energy averaging (KEA) model was based on a mass-fraction weighted particle velocity mixture rule and the conservation equations. The SCEOS model yielded the stiffest TATB EOS (0.121{micro} + 0.4958{micro}{sup 2} + 2.0473{micro}{sup 3}) and, when incorporated in mesoscale simulations of the ICE, demonstrated the best agreement with VISAR velocity data for both specimen thicknesses. The SCCE model yielded a relatively more compliant EOS (0.1999{micro}-0.6967{micro}{sup 2} + 4.9546{micro}{sup 3}) and the KEA model yielded the most compliant EOS (0.1999{micro}-0.6967{micro}{sup 2}+4.9546{micro}{sup 3}) of all the equilibrium mixture models. Mesoscale simulations with the lower density TATB adiabatic EOS data demonstrated the least agreement with VISAR velocity data.

Springer, H K; Willey, T M; Friedman, G; Fried, L E; Vandersall, K S; Baer, M R

2010-03-06T23:59:59.000Z

Note: This page contains sample records for the topic "mesoscale convective systems" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

Center for Mesoscale Transport Properties (m2M) | U.S. DOE Office...  

Office of Science (SC) Website

from molecular to mesoscale (m2m); to minimize heat and maximize work of electrical energy storage devices. Research Topics energy storage (including batteries and...

142

Laminar boundary layers in convective heat transport  

E-Print Network [OSTI]

We study Rayleigh-Benard convection in the high-Rayleigh-number and high-Prandtl-number regime, i.e., we consider a fluid in a container that is exposed to strong heating of the bottom and cooling of the top plate in the absence of inertia effects. While the dynamics in the bulk are characterized by a chaotic convective heat flow, the boundary layers at the horizontal container plates are essentially conducting and thus the fluid is motionless. Consequently, the average temperature exhibits a linear profile in the boundary layers. In this article, we rigorously investigate the average temperature and oscillations in the boundary layer via local bounds on the temperature field. Moreover, we deduce that the temperature profile is indeed essentially linear close to the horizontal container plates. Our results are uniform in the system parameters (e.g. the Rayleigh number) up to logarithmic correction terms. An important tool in our analysis is a new Hardy-type estimate for the convecting velocity field, which can be used to control the fluid motion in the layer. The bounds on the temperature field are derived with the help of local maximal regularity estimates for convection-diffusion equations.

Christian Seis

2012-12-12T23:59:59.000Z

143

Convection in X-ray Bursts Michael Zingale Stony Brook University  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

many stellar systems dominated by convective transport of energy - Supernovae (both thermonuclear and gravitational) - X-ray bursts and novae (thermonuclear explosion of accreted...

144

The Phenix ultimate natural convection test  

SciTech Connect (OSTI)

The French sodium cooled fast reactor Phenix was shut down in 2009 after 35 years of operation. Before decommissioning, a final set of tests were performed by the CEA during 9 months. Several topics were involved such as thermal hydraulics, core physics and fuel behaviour. Among these ultimate experiments, two thermal hydraulic tests were performed: an asymmetrical test consisting in a trip of one secondary pump and a natural convection test in the primary circuit. Recognizing the unique opportunity offered by these Phenix ultimate tests, IAEA decided in 2007 to launch a Coordinated Research Project (CRP) devoted to benchmarking analyses with system codes on the Phenix natural convection test. One objective of the natural convection test in Phenix reactor is the assessment of the CATHARE system code for safety studies on future and advanced sodium cooled fast reactors. The aim of this paper is to describe this test, which was performed on June 22-23, 2009, and the associated benchmark specifications for the CRP work. The paper reminds briefly the Phenix reactor with the main physical parameters and the instrumentation used during the natural convection test. After that, the test scenario is described: - initial state at a power of 120 MWth, - test beginning resulting from a manual dry out of the two steam generators, - manual scram, - manual trip on the three primary pumps without back-up by pony motors, - setting and development of natural convection in the primary circuit, in a first phase without significant heat sink in the secondary circuits and in a second phase with significant heat sink in the secondary circuits, by opening the casing of steam generators to create an efficient heat sink, by air natural circulation in the steam generators casing. The benchmark case ends after this second phase, which corresponds to the experimental test duration of nearly 7 hours. The paper presents also the benchmark specifications data supplied by the CEA to all participants of this CRP in order to perform calculations (core, primary circuit, primary pumps, IHX, shutdown system, operating parameters, test scenario and real test conditions). Finally, main test results and analyses are presented including the evolution of the core and of the heat exchangers inlet and outlet temperatures, and some local temperature measurements. The natural convection has been easily set up in the pool type reactor Phenix with different boundary conditions at the secondary side, with or without heat sink. The data obtained during this unique test represent some very useful and precious results for the development of SFR in a wide range of thematic such as numerical methods dedicated to thermal-hydraulics safety analyses (system codes, CFD codes and coupling system and CFD codes) and instrumentation. (authors)

Gauthe, P. [CEA, DER, SESI, F-13108, Saint Paul lez Durance (France); Pialla, D.; Tenchine, D. [CEA, DEN, STMF, F-38054, Grenoble (France); Vasile, A. [CEA, DER, SESI, F-13108, Saint Paul lez Durance (France); Rochwerger, D. [CEA, DEN, DEIM, F-30207, Bagnols-sur-Ceze (France)

2012-07-01T23:59:59.000Z

145

Divergent subcritical convection in magnetized plasma from asymmetric sourcing  

SciTech Connect (OSTI)

Asymmetric particle and heat sourcing in a plasma confined in a closed magnetic field line configuration results in convection cells, as is well known. This phenomenon occurs even if the sourcing on average produces density and temperature profiles that are subcritical, i.e., magnetohydrodynamically stable to interchange modes. Such subcritical convection is expected to be small compared to the convection from supercritical driving for which the system is interchange unstable. The ratio of subcritical to supercritical convection is expected to scale as the inverse Reynolds numbers (for large Reynolds numbers). It is shown that this ratio is, in fact, considerably larger. As marginal stability is approached, the subcritical convection grows from very small to almost the unstable convection size, i.e., of order unity. This effect may be similar to why a driven, damped harmonic oscillator increases in amplitude as resonance is approached. A numerical simulation is done to demonstrate this effect. It is also shown that transport from the large convection can be substantial.

Adler, D.T.; Hassam, A.B. [Department of Physics, University of Maryland, College Park, Maryland 20742 (United States)

2005-06-15T23:59:59.000Z

146

Different convection models in ATLAS  

E-Print Network [OSTI]

Convection is an important phenomenon in the atmospheres of A-type and cooler stars. A description of convection in ATLAS models is presented, together with details of how it is specified in model calculations. The effects of changing the treatment of convection on model structures and how this affects observable quantities are discussed. The role of microturbulence is examined, and its link to velocity fields within the atmosphere. Far from being free parameters, mixing-length and microturbulence should be constrained in model calculations.

Barry Smalley

2005-09-19T23:59:59.000Z

147

Slide 1  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

a Mesoscale Convective System Sampled During TWP-ICE: Analysis via Water Budget Equations Jasmine Cetrone and Robert Houze University of Washington Introduction This study computes...

148

Diffractive imaging at large Fresnel number: Challenge of dynamic mesoscale imaging with hard x rays  

Science Journals Connector (OSTI)

Real materials have structure at both the atomic or crystalline scale as well as at interfaces and defects at the larger scale of grains. There is a need for the study of materials at the “mesoscale,” the scale at which subgranular physical processes and intergranular organization couple to determine microstructure, crucially impacting constitutive response at the engineering macroscale. Diffractive imaging using photons that can penetrate multiple grains of material would be a transformative technique for the study of the performance of materials in dynamic extremes. Thicker samples imply higher energy photons of shorter wavelength, and imaging of multiple grains implies bigger spot sizes. Such imaging requires the use of future planned and proposed hard x-ray free electron lasers (such as the European XFEL) to provide both the spatial coherence transverse to the large spots and the peak brilliance to provide the short illumination times. The result is that the Fresnel number of the system becomes large and is no longer in the Fraunhofer far-field limit. The interrelated issues of diffractive imaging at large Fresnel number are analyzed, including proof that diffractive imaging is possible in this limit and estimates of the signal-to-noise possible. In addition, derivation of the heating rates for brilliant pulses of x rays are presented. The potential and limitations on multiple dynamic images are derived. This paper will present a study of x-ray interactions with materials in this new regime of spatially coherent but relatively large mesoscale spots at very hard energies. It should provide the theory and design background for the experiments and facilities required to control materials in extreme environments, in particular for the next generation of very-hard-x-ray free electron lasers.

John L. Barber; Cris W. Barnes; Richard L. Sandberg; Richard L. Sheffield

2014-05-12T23:59:59.000Z

149

Isentropic Analysis of Convective Motions  

Science Journals Connector (OSTI)

This paper analyzes the convective mass transport by sorting air parcels in terms of their equivalent potential temperature to determine an isentropic streamfunction. By averaging the vertical mass flux at a constant value of the equivalent ...

Olivier M. Pauluis; Agnieszka A. Mrowiec

2013-11-01T23:59:59.000Z

150

Mesoscale coupled ocean-atmosphere feedbacks in boundary current systems  

E-Print Network [OSTI]

response of the ocean eddies . The power spectrum of thethe ocean. As such, the larger energy in the power spectrumocean eddies. On the other hand, Smoothed ROMS has higher power

Putrasahan, Dian Ariyani

2012-01-01T23:59:59.000Z

151

Turbulent Compressible Convection with Rotation - Penetration above a Convection Zone  

E-Print Network [OSTI]

We perform Large eddy simulations of turbulent compressible convection in stellar-type convection zones by solving the Navi\\'{e}r-Stokes equations in three dimensions. We estimate the extent of penetration into the stable layer above a stellar-type convection zone by varying the rotation rate ({\\boldmath$\\rm\\Omega$}), the inclination of the rotation vector ($\\theta$) and the relative stability ($S$) of the upper stable layer. The computational domain is a rectangular box in an f-plane configuration and is divided into two regions of unstable and stable stratification with the stable layer placed above the convectively unstable layer. Several models have been computed and the penetration distance into the stable layer above the convection zone is estimated by determining the position where time averaged kinetic energy flux has the first zero in the upper stable layer. The vertical grid spacing in all the model is non-uniform, and is less in the upper region so that the flows are better resolved in the region of interest. We find that the penetration distance increases as the rotation rate increases for the case when the rotation vector is aligned with the vertical axis. However, with the increase in the stability of the upper stable layer, the upward penetration distance decreases. Since we are not able to afford computations with finer resolution for all the models, we compute a number of models to see the effect of increased resolution on the upward penetration. In addition, we estimate the upper limit on the upward convective penetration from stellar convective cores.

Partha S. Pal; Harinder P. Singh; Kwing L. Chan; M. P. Srivastava

2008-02-13T23:59:59.000Z

152

Convective heat flow probe  

DOE Patents [OSTI]

A convective heat flow probe device is provided which measures heat flow and fluid flow magnitude in the formation surrounding a borehole. The probe comprises an elongate housing adapted to be lowered down into the borehole; a plurality of heaters extending along the probe for heating the formation surrounding the borehole; a plurality of temperature sensors arranged around the periphery of the probe for measuring the temperature of the surrounding formation after heating thereof by the heater elements. The temperature sensors and heater elements are mounted in a plurality of separate heater pads which are supported by the housing and which are adapted to be radially expanded into firm engagement with the walls of the borehole. The heat supplied by the heater elements and the temperatures measured by the temperature sensors are monitored and used in providing the desired measurements. The outer peripheral surfaces of the heater pads are configured as segments of a cylinder and form a full cylinder when taken together. A plurality of temperature sensors are located on each pad so as to extend along the length and across the width thereof, with a heating element being located in each pad beneath the temperature sensors. An expansion mechanism driven by a clamping motor provides expansion and retraction of the heater pads and expandable packet-type seals are provided along the probe above and below the heater pads.

Dunn, J.C.; Hardee, H.C.; Striker, R.P.

1984-01-09T23:59:59.000Z

153

An analytical coarse-graining method which preserves the free energy, structural correlations, and thermodynamic state of polymer melts from the atomistic to the mesoscale  

SciTech Connect (OSTI)

Structural and thermodynamic consistency of coarse-graining models across multiple length scales is essential for the predictive role of multi-scale modeling and molecular dynamic simulations that use mesoscale descriptions. Our approach is a coarse-grained model based on integral equation theory, which can represent polymer chains at variable levels of chemical details. The model is analytical and depends on molecular and thermodynamic parameters of the system under study, as well as on the direct correlation function in the k ? 0 limit, c{sub 0}. A numerical solution to the PRISM integral equations is used to determine c{sub 0}, by adjusting the value of the effective hard sphere diameter, d{sub HS}, to agree with the predicted equation of state. This single quantity parameterizes the coarse-grained potential, which is used to perform mesoscale simulations that are directly compared with atomistic-level simulations of the same system. We test our coarse-graining formalism by comparing structural correlations, isothermal compressibility, equation of state, Helmholtz and Gibbs free energies, and potential energy and entropy using both united atom and coarse-grained descriptions. We find quantitative agreement between the analytical formalism for the thermodynamic properties, and the results of Molecular Dynamics simulations, independent of the chosen level of representation. In the mesoscale description, the potential energy of the soft-particle interaction becomes a free energy in the coarse-grained coordinates which preserves the excess free energy from an ideal gas across all levels of description. The structural consistency between the united-atom and mesoscale descriptions means the relative entropy between descriptions has been minimized without any variational optimization parameters. The approach is general and applicable to any polymeric system in different thermodynamic conditions.

McCarty, J.; Clark, A. J.; Copperman, J.; Guenza, M. G., E-mail: mguenza@uoregon.edu [Department of Chemistry and Biochemistry, and Institute of Theoretical Science, University of Oregon, Eugene, Oregon 97403 (United States)

2014-05-28T23:59:59.000Z

154

Natural Convection Shutdown Heat Removal Test Facility (NSTF)  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Natural Convection Natural Convection Shutdown Heat Removal Test Facility Scaling Basis Full Scale Half Scale NSTF Argonne National Laboratory's Natural Convection Shutdown Heat Removal Test Facility (NSTF) - one of the world's largest facilities for ex-vessel passive decay heat removal testing-confirms the performance of reactor cavity cooling systems (RCCS) and similar passive confinement or containment decay heat removal systems in modern Small Modular Reactors. Originally built to aid in the development of General Electric's Power Reactor Innovative Small Module (PRISM) Reactor Vessel Auxiliary Cooling System (RVACS), the NSTF has a long history of providing confirmatory data for the airside of the RVACS. Argonne National Laboratory's NSTF is a state-of-the-art, large-scale facility for evaluating performance

155

Environment and the Lifetime of Tropical Deep Convection in a Cloud-Permitting Regional Model Simulation  

SciTech Connect (OSTI)

By applying a cloud tracking algorithm to tropical convective systems simulated by a regional high resolution model, the study documents environmental conditions before and after convective systems are initiated over ocean and land by following them during their lifetime. The comparative roles of various environmental fields in affecting the lifetime of convection are also quantified. The statistics of lifetime, maximum area, propagation speed and direction of the simulated deep convection agrees well with geostationary satellite observations. Over ocean, convective systems enhance surface fluxes through the associated wind gusts as well as cooling and drying of the boundary layer. A significant relationship is found between the mean surface fluxes during their lifetime and the longevity of the systems which in turn is related to the initial intensity of the moist updraft and to a lesser extent upper level shear. Over land, on the other hand, convective activity suppresses surface fluxes through cloud cover and the lifetime of convection is related to the upper level shear during their lifetime and strength of the heat fluxes several hours before the initiation of convection. For systems of equal lifetime, those over land are significantly more intense than those over ocean especially during early stages of their lifetime.

Hagos, Samson M.; Feng, Zhe; McFarlane, Sally A.; Leung, Lai-Yung R.

2013-08-01T23:59:59.000Z

156

TY JOUR T1 Mesoscale Climatic Simulation of Surface Air Temperature Cooling  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Mesoscale Climatic Simulation of Surface Air Temperature Cooling Mesoscale Climatic Simulation of Surface Air Temperature Cooling by Highly Reflective Greenhouses in SE Spain JF Environmental Science Technology A1 Campra Pablo A1 Dev Millstein KW buildings KW Heat Island Group AB p span A long term local cooling trend in surface air temperature has been monitored at the largest concentration of reflective greenhouses in the world at the Province of Almeria SE Spain associated with a dramatic increase in surface albedo in the area The availability of reliable long term climatic field data at this site offers a unique opportunity to test the skill of mesoscale meteorological models describing and predicting the impacts of land use change on local climate Using the Weather Research and Forecast WRF mesoscale model we have run a

157

Simulating Typhoon Floods with Gauge Data and Mesoscale-Modeled Rainfall in a Mountainous Watershed  

Science Journals Connector (OSTI)

A physically based distributed hydrological model was applied to simulate typhoon floods over a mountainous watershed in Taiwan. The meteorological forcings include the observed gauge rainfall data and the predicted rainfall data from a mesoscale ...

Ming-Hsu Li; Ming-Jen Yang; Ruitang Soong; Hsiao-Ling Huang

2005-06-01T23:59:59.000Z

158

Meso-scale eddies affect near-surface turbulent exchange: evidence from lidar and tower measurements  

Science Journals Connector (OSTI)

The eddy-covariance technique tends to underestimate the turbulent heat fluxes, which results in the non-closure of the surface energy balance. This study shows experimental evidence that meso-scale turbulent organized structures, which are ...

Fabian Eder; Marius Schmidt; Thomas Damian; Katja Träumner; Matthias Mauder

159

Evolution of Mesoscale Precipitation Band Environments within the Comma Head of Northeast U.S. Cyclones  

Science Journals Connector (OSTI)

This paper explores the mesoscale forcing and stability evolution of intense precipitation bands in the comma head sector of extratropical cyclones using the 32-km North American Regional Reanalysis, hourly 20-km Rapid Update Cycle analyses, and ...

David R. Novak; Brian A. Colle; Anantha R. Aiyyer

2010-06-01T23:59:59.000Z

160

Seasonal Mesoscale and Submesoscale Eddy Variability along the North Pacific Subtropical Countercurrent  

Science Journals Connector (OSTI)

Located at the center of the western North Pacific Subtropical Gyre, the Subtropical Countercurrent (STCC) is not only abundant in mesoscale eddies, but also exhibits prominent submesoscale eddy features. Output from a ° high-resolution OGCM ...

Bo Qiu; Shuiming Chen; Patrice Klein; Hideharu Sasaki; Yoshikazu Sasai

2014-12-01T23:59:59.000Z

Note: This page contains sample records for the topic "mesoscale convective systems" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

Tests of an ensemble Kalman filter for mesoscale and regional-scale data assimilation  

E-Print Network [OSTI]

This dissertation examines the performance of an ensemble Kalman filter (EnKF) implemented in a mesoscale model in increasingly realistic contexts from under a perfect model assumption and in the presence of significant model error with synthetic...

Meng, Zhiyong

2007-09-17T23:59:59.000Z

162

The supercell thunderstorm on 8 June 1990: Mesoscale analysis and radar observations  

Science Journals Connector (OSTI)

Surface mesoscale analysis helps to explain these different storm evolutions due to interaction among local circulations, Adriatic Sea and orography. While dry wind (foehn) dumps the thermodynamic instability in ...

P. P. Alberoni; S. Nanni; M. Crespi; M. Monai

1996-01-01T23:59:59.000Z

163

Analysis of 11 june 2003 mesoscale convective vortex genesis using weather surveillance radar ??88 doppler (wsr-88d)  

E-Print Network [OSTI]

, radar, and surface analysis of the synoptic environment valid at 0000 UTC 11 June 2003????????? 17 1.11. 850 mb WRF 10 km resolution forecast model for 0000 UTC 11 June 2003..??????????????????????.. 18 ix FIGURE... Page 1.12. Surface to 3km wind shear WRF 10 km resolution forecast model for 0000 UTC 11 June 2003???????????????? 19 1.13. 500 mb WRF 10 km resolution forecast model for 0000 UTC 11 June 2003??????????????????????? 20 1.14. 0000 UTC 11...

Reynolds, Amber Elizabeth

2009-05-15T23:59:59.000Z

164

Heuristic correction of wind speed mesoscale models simulations for wind farms prospecting and micrositing  

Science Journals Connector (OSTI)

Abstract The distribution of surface-level wind speeds over a given area is important information that is related to several processes in wind farm prospecting, design and micrositing. This information is often obtained from simulations using mesoscale models that take variables from global models as starting points. Improved outputs from mesoscale models can lead to reduced error compared to real wind speeds in the study area if in situ wind speed measurements are available. In this paper, we present several techniques to correct surface wind speed simulations from mesoscale models using data from measuring stations in wind farms. Specifically, we propose different heuristic corrections of the outputs from mesoscale models by means of surface fitting between the Weibull parameters of the wind speed series (from the mesoscale model) and those from the measuring stations (real wind speed) in the wind farm. The proposed methodology has direct applications in wind farm design, site prospection and micrositing. The good performance of our method is evident in the more accurate surface wind speeds obtained from mesoscale models in two wind farm prospection sites in Spain, where several measuring towers are installed.

B. Saavedra-Moreno; S. Salcedo-Sanz; C. Casanova-Mateo; J.A. Portilla-Figueras; L. Prieto

2014-01-01T23:59:59.000Z

165

Convection automated logic oven control  

SciTech Connect (OSTI)

For the past few years, there has been a greater push to bring more automation to the cooling process. There have been attempts at automated cooking using a wide range of sensors and procedures, but with limited success. The authors have the answer to the automated cooking process; this patented technology is called Convection AutoLogic (CAL). The beauty of the technology is that it requires no extra hardware for the existing oven system. They use the existing temperature probe, whether it is an RTD, thermocouple, or thermistor. This means that the manufacturer does not have to be burdened with extra costs associated with automated cooking in comparison to standard ovens. The only change to the oven is the program in the central processing unit (CPU) on the board. As for its operation, when the user places the food into the oven, he or she is required to select a category (e.g., beef, poultry, or casseroles) and then simply press the start button. The CAL program then begins its cooking program. It first looks at the ambient oven temperature to see if it is a cold, warm, or hot start. CAL stores this data and then begins to look at the food`s thermal footprint. After CAL has properly detected this thermal footprint, it can calculate the time and temperature at which the food needs to be cooked. CAL then sets up these factors for the cooking stage of the program and, when the food has finished cooking, the oven is turned off automatically. The total time for this entire process is the same as the standard cooking time the user would normally set. The CAL program can also compensate for varying line voltages and detect when the oven door is opened. With all of these varying factors being monitored, CAL can produce a perfectly cooked item with minimal user input.

Boyer, M.A.; Eke, K.I. [Apollo U.S.A. Inc., Orlando, FL (United States)] [Apollo U.S.A. Inc., Orlando, FL (United States)

1998-03-01T23:59:59.000Z

166

A dual mass flux framework for boundary layer convection  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

A dual mass flux framework for boundary layer convection A dual mass flux framework for boundary layer convection Neggers, Roel European Centre for Medium-range Weather Forecasts (ECMWF) Category: Modeling A new convective boundary layer scheme is presented that is currently being developed for the Integrated Forecasting System (IFS) of the European Centre for Medium-range Weather Forecasts (ECMWF). Part of the total turbulent flux is modeled through advective mass flux by multiple updrafts, initialized at the surface. Two groups of updrafts are explicitly represented; i) updrafts that never reach their lifting condensation level, and ii) updrafts that condensate and become cloudy. Key new ingredient is the flexibility of the associated updraft area fractions, as a function of model state. As a result, an extra degree of freedom is introduced in the

167

Title: Radar-observed convective characteristics during TWP-ICE  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Title: Radar-observed convective characteristics during TWP-ICE Title: Radar-observed convective characteristics during TWP-ICE Schumacher, Courtney Texas A&M University Houze, Robert University of Washington May, Peter Bureau or Meteorology Research Centre Frederick, Kaycee Cetrone, Jasmine Vallgren, Andreas Category: Field Campaigns This poster will describe the radar dataset obtained in the Tropical Warm Pool International Cloud Experiment (TWP-ICE), which is to take place 20 January - 14 February 2006 in the vicinity of Darwin, Australia. We will describe the convective systems observed during the project by two scanning C-band Doppler radars, one of which will provide dual-polarization measurements, and ARM's vertically pointing cloud radar and lidar installations. In addition, we will discuss the potential for combining

168

ARM - Midlatitude Continental Convective Clouds (comstock-hvps)  

DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

Convective processes play a critical role in the Earth's energy balance through the redistribution of heat and moisture in the atmosphere and their link to the hydrological cycle. Accurate representation of convective processes in numerical models is vital towards improving current and future simulations of Earths climate system. Despite improvements in computing power, current operational weather and global climate models are unable to resolve the natural temporal and spatial scales important to convective processes and therefore must turn to parameterization schemes to represent these processes. In turn, parameterization schemes in cloud-resolving models need to be evaluated for their generality and application to a variety of atmospheric conditions. Data from field campaigns with appropriate forcing descriptors have been traditionally used by modelers for evaluating and improving parameterization schemes.

Jensen, Mike; Comstock, Jennifer; Genio, Anthony Del; Giangrande, Scott; Kollias, Pavlos

169

A transilient matrix for moist convection  

SciTech Connect (OSTI)

A method is introduced for diagnosing a transilient matrix for moist convection. This transilient matrix quantifies the nonlocal transport of air by convective eddies: for every height z, it gives the distribution of starting heights z{prime} for the eddies that arrive at z. In a cloud-resolving simulation of deep convection, the transilient matrix shows that two-thirds of the subcloud air convecting into the free troposphere originates from within 100 m of the surface. This finding clarifies which initial height to use when calculating convective available potential energy from soundings of the tropical troposphere.

Romps, D.; Kuang, Z.

2011-08-15T23:59:59.000Z

170

MICRO-SEISMOMETERS VIA ADVANCED MESO-SCALE FABRICATION  

SciTech Connect (OSTI)

The Department of Energy (DOE) and the National Nuclear Security Administration (NNSA) seek revolutionary sensing innovations for the monitoring of nuclear detonations. Performance specifications are to be consistent with those obtainable by only an elite few products available today, but with orders of magnitude reduction in size, weight, power, and cost. The proposed commercial innovation calls upon several technologies including the combination of meso-scale fabrication and assembly, photonics-based displacement / motion detection methods, and the use of digital control electronics . Early Phase II development has demonstrated verified and repeatable sub 2ng noise floor from 3Hz to 100Hz, compact integration of 3-axis prototypes, and robust deployment exercises. Ongoing developments are focusing on low frequency challenges, low power consumption, ultra-miniature size, and low cross axis sensitivity. We are also addressing the rigorous set of specifications required for repeatable and reliable long-term explosion monitoring, including thermal stability, reduced recovery time from mass re-centering and large mechanical shocks, sensitivity stability, and transportability. Successful implementation will result in small, hand-held demonstration units with the ability to address national security needs of the DOE/NNSA. Additional applications envisioned include military/defense, scientific instrumentation, oil and gas exploration, inertial navigation, and civil infrastructure monitoring.

Garcia, Caesar A; Onaran, Guclu; Avenson, Brad; Hall, Neal

2014-11-07T23:59:59.000Z

171

Towards quantifying mesoscale flows in the troposphere using Raman lidar and sondes  

SciTech Connect (OSTI)

Water vapor plays an important role in the energetics of the boundary layer processes which in turn play a key role in regulating regional and global climate. It plays a primary role in Earth`s hydrological cycle, in radiation balance as a direct absorber of infrared radiation, and in atmospheric circulation as a latent heat energy source as well as in determining cloud development and atmospheric stability. Water vapor concentration, expressed as a mass mixing ratio, is conserved in all meteorological processes except condensation and evaporation. This property makes it an ideal choice for studying many of the atmosphere`s dynamic features. Raman scattering measurements from lidar also allow retrieval of water vapor mixing ratio profiles at high temporal and vertical resolution. Raman lidars sense water vapor to altitudes not achievable with towers and surface systems, sample the atmosphere at much higher temporal resolution than radiosondes or satellites, and do not require strong vertical gradients or turbulent fluctuations in temperature that is required by acoustic sounders and radars. Analysis of highly resolved water vapor profiles are used here to characterize two important mesoscale flows: thunderstorm outflows and a cold front passage.

Demoz, B.; Evans, K. [Univ. of Maryland Baltimore County, Baltimore, MD (United States); Starr, D. [NASA, Greenbelt, MD (United States). Goddard Space Flight Center] [and others

1998-03-01T23:59:59.000Z

172

The reduction of plankton biomass induced by mesoscale stirring: a modeling study in the Benguela upwelling  

E-Print Network [OSTI]

Recent studies, both based on remote sensed data and coupled models, showed a reduction of biological productivity due to vigorous horizontal stirring in upwelling areas. In order to better understand this phenomenon, we consider a system of oceanic flow from the Benguela area coupled with a simple biogeochemical model of Nutrient-Phyto-Zooplankton (NPZ) type. For the flow three different surface velocity fields are considered: one derived from satellite altimetry data, and the other two from a regional numerical model at two different spatial resolutions. We compute horizontal particle dispersion in terms of Lyapunov Exponents, and analyzed their correlations with phytoplankton concentrations. Our modelling approach confirms that in the south Benguela there is a reduction of biological activity when stirring is increased. Two-dimensional offshore advection and latitudinal difference in Primary Production, also mediated by the flow, seem to be the dominant processes involved. We estimate that mesoscale processes are responsible for 30 to 50% of the offshore fluxes of biological tracers. In the northern area, other factors not taken into account in our simulation are influencing the ecosystem. We suggest explanations for these results in the context of studies performed in other eastern boundary upwelling areas.

Ismael Hernández-Carrasco; Vincent Rossi; Emilio Hernández-García; Veronique Garçon; Cristóbal López

2013-11-05T23:59:59.000Z

173

Midlatitude Continental Convective Clouds Experiment (MC3E)  

SciTech Connect (OSTI)

Convective processes play a critical role in the Earth’s energy balance through the redistribution of heat and moisture in the atmosphere and subsequent impacts on the hydrologic cycle. Global observation and accurate representation of these processes in numerical models is vital to improving our current understanding and future simulations of Earth’s climate system. Despite improvements in computing power, current operational weather and global climate models are unable to resolve the natural temporal and spatial scales that are associated with convective and stratiform precipitation processes; therefore, they must turn to parameterization schemes to represent these processes. In turn, the physical basis for these parameterization schemes needs to be evaluated for general application under a variety of atmospheric conditions. Analogously, space-based remote sensing algorithms designed to retrieve related cloud and precipitation information for use in hydrological, climate, and numerical weather prediction applications often rely on physical “parameterizations” that reliably translate indirectly related instrument measurements to the physical quantity of interest (e.g., precipitation rate). Importantly, both spaceborne retrieval algorithms and model convective parameterization schemes traditionally rely on field campaign data sets as a basis for evaluating and improving the physics of their respective approaches. The Midlatitude Continental Convective Clouds Experiment (MC3E) will take place in central Oklahoma during the April–May 2011 period. The experiment is a collaborative effort between the U.S. Department of Energy (DOE) Atmospheric Radiation Measurement (ARM) Climate Research Facility and the National Aeronautics and Space Administration’s (NASA) Global Precipitation Measurement (GPM) mission Ground Validation (GV) program. The field campaign leverages the unprecedented observing infrastructure currently available in the central United States, combined with an extensive sounding array, remote sensing and in situ aircraft observations, NASA GPM ground validation remote sensors, and new ARM instrumentation purchased with American Recovery and Reinvestment Act funding. The overarching goal is to provide the most complete characterization of convective cloud systems, precipitation, and the environment that has ever been obtained, providing constraints for model cumulus parameterizations and space-based rainfall retrieval algorithms over land that have never before been available. Several different components of convective cloud and precipitation processes tangible to both the convective parameterization and precipitation retrieval algorithm problem are targeted, such as preconvective environment and convective initiation, updraft/downdraft dynamics, condensate transport and detrainment, precipitation and cloud microphysics, spatial and temporal variability of precipitation, influence on the environment and radiation, and a detailed description of the large-scale forcing.

Jensen, MP; Petersen, WA; Del Genio, AD; Giangrande, SE; Heymsfield, A; Heymsfield, G; Hou, AY; Kollias, P; Orr, B; Rutledge, SA; Schwaller, MR; Zipser, E

2010-04-01T23:59:59.000Z

174

Pseudosteady-state mixed convection inside rotating spherical containers  

SciTech Connect (OSTI)

A computational study of the pseudosteady-state two-dimensional mixed convection within rotating spherical containers is presented. The computations are based on an iterative, finite-volume numerical procedure using primitive dependent variables, whereby the time-dependent continuity, momentum and energy equations in the spherical coordinate system are solved. Natural convection effect is modeled via the Boussinesq approximation. For a fixed Prandtl number of 4.62, parametric studies were performed by varying the Rayleigh number in order to cover the laminar regime adequately. For a given Rayleigh number, the ratio of Gr/Re{sup 2} was varied between 0.1 and 10. Given a Rayleigh number, the streamline patterns maintain their general shape with a dominant rotating vortex. As the forced convection effect becomes less marked, the streamlines exhibit less pronounced gradients near the surface of the sphere. As the rotational effect become more marked, the extent of the deviation from the limiting case of non-rotating spheres becomes more noticed. However, the bottom of the sphere still remains to be the region with enhanced heat transfer. Given a rotational Reynolds number, the streamline patterns are not affected greatly as the natural convection is promoted, however the temperature gradients near the surface are markedly enhanced. It is noticed that as natural convection effects are promoted, the greater portion of the sphere's surface experiences enhanced heat transfer rates. Given a Rayleigh number, the contours of the azimuthal velocity exhibit a nearly vertical equally-spaced pattern suggesting that solid-body rotation for high rotational Reynolds numbers. However, as the natural convection effects are enhanced, the contours become more slanted. The variation of the mean Nusselt number with the Reynolds and Rayleigh numbers is also quantified.

Khodadadi, J.M.; Li, W.; Shi, X.

1999-07-01T23:59:59.000Z

175

Convectively unstable wave packets in spatially developing open flows and media with algebraically decaying tails  

Science Journals Connector (OSTI)

...first recognized in the plasma physics literature (see Twiss 1951...absolute and convective. In Handbook of plasma physics (ed. M. N. Rosenbluth & R...Stability of traveling waves. In Handbook of dynamical systems II (ed...

2005-01-01T23:59:59.000Z

176

Characteristics of convective cells over the coastal regions of southeast Texas  

E-Print Network [OSTI]

Vertical profiles of radar reflectivity and cloud-to-ground lightning characteristics associated with convective cells were analyzed for mesoscate systems occurring over the coastal regions of southeast Texas during the spring and summer months...

Robinson, Michael

2012-06-07T23:59:59.000Z

177

Mesoscale Tank Experiments for Investigating Carbon Tetrachloride Biodegradation  

SciTech Connect (OSTI)

Mesoscale tank experiments were performed to simulate bioremediation of saturated zone carbon tetrachloride (CCl4) originating from a vadose zone carbon tetrachloride source. The mesoscale tank is 2-m wide by 2-m high by 3-m long and was constructed of stainless steel, yielding a total volume of 12 m3. Simulated geology within the tank consisted of two unconsolidated sand layers separated by a clay layer containing variable-sized stainless steel tubes that represented fractures within a consolidated porous medium. The thickness of the upper sand layer was approximately 55 cm, the thickness of the virtual fracture layer was 25 cm, and the thickness of the lower sand layer was approximately 98 cm. The water table was located at an elevation of approximately 54 cm from the bottom of the tank. CCl4 was added to the sealed tank by pouring 500 ml of neat CCl4 into a beaker buried approximately 10 cm below the upper sand surface through a stainless steel tube. The CCl4 was then allowed to partition through the reactor over time, eventually coming to equilibrium. Once CCl4 equilibrium had occurred in the saturated zone (~500 ppb); the reactor was bioaugmented with a CCl4 degrading culture enriched from the Subsurface Disposal Area at the INEEL. The culture was grown to a cell density of ~ 1.0 x 108 cells/ml and injected into the simulated aquifer through a center sampling port. Following injection of the culture, an initial aliquot of lactate (1,000 g/L), nitrogen, and phosphorus were added to the reactor. Lactate was injected every 3 – 5 days for one month. After 1 month of operation, a continuous supply of lactate (1,000 g/L) was pumped into the reactor at an average rate of 50 mL/min. CCl4 concentrations in the unsaturated zone were measured using hollow fiber membrane samplers, while liquid samples were analyzed to monitor levels in the simulated aquifer zone. Samples were also taken for analysis of volatile organic acids and cell density. As would be expected, increases in cell density over the length of the cell correlated with the flow of the water through the cell. One week following injection microbes and lactate, cell numbers were in the range of 5.0 x 106 cells/mL, by the end of the experiment cell numbers had increased to approximately 1.94 x 107 cells/mL. Five days after lactate injection was initiated, chloroform appeared in liquid samples taken for chlorinated VOC analysis. CCl4 concentrations in the liquid phase dropped to approximately 180 ppb. At the conclusion of the batch lactate injection phase of the bioaugmentation, CCl4 levels averaged 40 ppb and chloroform levels averaged 44 ppb. Interestingly, once continuous lactate addition was initiated, CCl4 concentrations in the saturated zone increased with spikes as high as 3,000 ppb. Chloroform concentrations also increased following continuous addition of lactate. Since the CCl4 source in the breaker had been depleted, vadose zone concentrations of CCl4 dropped steadily during addition of lactate to the saturated zone. CCl4 levels of ~ 800 ppmv were noted at the beginning of the experiment, levels decreased to below 200 ppmv by the end of the bioaugmentation phase. No chloroform was noted in the vadose zone during testing.

Brady D. Lee; Robert J. Lenhard

2005-06-01T23:59:59.000Z

178

Properties of tropical convection observed by ARM millimeter-radars  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Properties of tropical convection observed by ARM millimeter-radars Properties of tropical convection observed by ARM millimeter-radars Haynes, John Colorado State University Stephens, Graeme Colorado State University Category: Cloud Properties The results of an analysis of tropical cloud systems observed from a variety of vertically pointing radar systems are described. In particular, observations taken during five years of operation of the ARM millimeter wavelength radar system (MMCR) at Manus Island in the Tropical West Pacific region are characterized into cloud classes according to the radar reflectivity structures of these cloud systems, associated rainfall, and surface radiative properties. These observations of cloud properties are composited with respect to various phases of the Madden Julian Oscillation, which is a dominant mode of variability at Manus Island. A method of better

179

RADIAL STELLAR PULSATION AND THREE-DIMENSIONAL CONVECTION. II. TWO-DIMENSIONAL CONVECTION IN FULL AMPLITUDE RADIAL PULSATION  

SciTech Connect (OSTI)

We have developed a three-dimensional radiation hydrodynamics code to simulate the interaction of convection and radial pulsation in classical variable stars. One key goal is the ability to carry these simulations to full amplitude in order to compare them with observed light curves. Previous multi-dimensional calculations were prevented from reaching full amplitude because of drift in the radial coordinate system, due to the algorithm defining radial movement of the coordinate system during the pulsation cycle. We have removed this difficulty by defining our radial coordinate flow algorithm to require that the mass in a spherical shell remain constant for every time step throughout the pulsation cycle. We have used our new code to perform two-dimensional (2D) simulations of the interaction of radial pulsation and convection. We have made comparisons between light curves from our 2D convective simulations with observed light curves and find that our 2D simulated light curves are better able to match the observed light curve shape near the red edge of the RR Lyrae instability strip than light curves from previous one-dimensional time-dependent convective models.

Geroux, Chris M.; Deupree, Robert G., E-mail: geroux@astro.ex.ac.uk [Institute for Computational Astrophysics and Department of Astronomy and Physics, Saint Mary's University, Halifax, NS B3H 3C3 (Canada)

2013-07-10T23:59:59.000Z

180

The structure of the solar convective overshooting zone  

Science Journals Connector (OSTI)

......turbulent kinetic energy fluxes , and super-adiabatic...convection model of the solar convection envelope...the convective energy flux becomes negative...the base of the solar convection zone...that convective energy transfer is very...distance. In the solar atmosphere, the...the National Key Project through grant......

D.R. Xiong; L. Deng

2001-11-11T23:59:59.000Z

Note: This page contains sample records for the topic "mesoscale convective systems" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

M. Bahrami ENSC 388 (F09) Forced Convection Heat Transfer 1 Forced Convection Heat Transfer  

E-Print Network [OSTI]

1 Forced Convection Heat Transfer Convection is the mechanism of heat transfer through a fluid / The convective heat transfer coefficient h strongly depends on the fluid properties and roughness of the solid. As a result, the heat transfer from the solid surface to the fluid layer adjacent to the surface

Bahrami, Majid

182

Slide 1Falk Herwig7 Aug 2006 Convective and non-convective mixing  

E-Print Network [OSTI]

Slide 1Falk Herwig7 Aug 2006 Convective and non-convective mixing in AGB stars Falk Herwig and Bernd Freytag Los Alamos National Laboratory Theoretical Astrophysics Group #12;Slide 2Falk Herwig7 Aug envelope models for sun-like stars #12;Slide 3Falk Herwig7 Aug 2006 3D hydro simulations of AGB convective

Herwig, Falk

183

Magnetic particle mixing with magnetic micro-convection for microfluidics  

Science Journals Connector (OSTI)

Abstract In this paper we discuss the magnetic micro-convection phenomenon as a tool for mixing enhancement in microfluidics systems in cases when one of the miscible fluids is a magnetic particle colloid. A system of a water-based magnetic fluid and water is investigated experimentally under homogeneous magnetic field in a Hele–Shaw cell. Subsequent image analysis both qualitatively and quantitatively reveals the high enhancement of mixing efficiency provided by this method. The mixing efficiency dependence on the magnetic field and the physical limits is discussed. A suitable model for a continuous-flow microfluidics setup for mixing with magnetic micro-convection is also proposed and justified with an experiment. In addition, possible applications in improving the speed of ferrohydrodynamic sorting and magnetic label or selected tracer mixing in lab on a chip systems are noted.

Guntars Kitenbergs; Kaspars E¯rglis; Régine Perzynski; Andrejs C?bers

2014-01-01T23:59:59.000Z

184

Modelled and observed variability of the atmospheric circulation the Peruvian Current System: 2000-2005  

E-Print Network [OSTI]

on the characteristics of the local equatorward atmospheric circulation. Resolving the mesoscale variability of the heat Mesoscale Model (MM5) and Weather Research and Forecasting (WRF) that were run over the Peruvian Current System (PCS) [0N-19°S; 83°W-68°W] from November 2000- October 2005. Wind data as derived from

185

Formation of Meso-Scale Roughening in 6022-T4 Al Sheets Deformed in Plane-Strain Tension  

E-Print Network [OSTI]

Meso-scale surface roughening evolution in 6022-T4 Al sheets was investigated using plane-strain tension. Formation of grain-scale hills and valleys and their relation to the morphologies and corresponding orientations of surface grains after deformation were examined experimentally. These observations were analyzed using various approaches based on the Schmid and Taylor crystal plasticity models. It was observed that surface grains with and without slip bands tend to form valleys and hills, respectively, wherever these two types of grains are adjacent to each other along the planestrain tension direction. When the sample was pulled along the transverse direction, the formation of hills and valleys by unbanded and banded grains was more lineally organized in the plane-strain (rolling) direction than in the sample which was pulled along the rolling direction. Slip banding and valley formation were principally observed in the surface grains with either very few (1?2) slip systems of high Schmid factors or low Taylor factors, in contrast to non slip-banded and hillforming surface grains. Quantitative analysis using correlation coefficients showed that the Schmid factor provided slightly better agreement than the Taylor factor in predicting slip-banding (and valley-forming) and non slip-banding (and hill-forming) behaviors of surface grains. In addition, measures that quantify the image qualities of EBSPs for selected surface grains suggested that the slip-banded and valley-forming grains contain less lattice distortion than the non slip-banded and Currently at Department of Civil and Environmental Engineering, Carnegie Mellon University, PAhill-forming grains despite the larger strains experienced by these grains. This indicates that dislocations in the slip-banded grains move out of the surface to create deformation without lattice distortion. Plastic interactions between specific neighboring grains are central to the formation of meso-scale surface roughening. 1.

unknown authors

186

Meso-Scale Planning for Multi-Agent Navigation Liang He Jur van den Berg  

E-Print Network [OSTI]

Meso-Scale Planning for Multi-Agent Navigation Liang He Jur van den Berg Abstract-- We introduce are with the of School of Computing, University of Utah. E-mail: lianghe.hust@gmail.com, berg@cs.utah.edu. Fig. 1

van den Berg, Jur

187

Mesoscale energetics and ows induced by sea-land and mountain-valley contrasts  

E-Print Network [OSTI]

Mesoscale energetics and ¯ows induced by sea-land and mountain-valley contrasts S. Federico1 , G. A October 1999 Abstract. We study the relative importance of sea-land and mountain-valley thermal contrasts and the west-facing slopes in the afternoon. The local thermally driven winds follow the development

Paris-Sud XI, Université de

188

ADVANCES IN ATMOSPHERIC SCIENCES, VOL. 27, NO. 2, 2010, 243252 Mesoscale Barotropic Instability of Vortex Rossby  

E-Print Network [OSTI]

ADVANCES IN ATMOSPHERIC SCIENCES, VOL. 27, NO. 2, 2010, 243­252 Mesoscale Barotropic Instability of Vortex Rossby Waves in Tropical Cyclones ZHONG Wei1 ( Í), LU Han-Cheng1 (ö ), and Da-Lin ZHANG2 1 Institute of Meteorology, PLA University of Science and Technology, Nanjing 211101 2 Department

Zhang, Da-Lin

189

Spatial-temporal mesoscale modelling of rainfall intensity using gage and radar data  

E-Print Network [OSTI]

Spatial-temporal mesoscale modelling of rainfall intensity using gage and radar data Montserrat fields. Doppler radar data offer better spatial and temporal coverage, but Doppler radar measures values. We use spatial logistic regression to model the probability of rain for both sources of data

Reich, Brian J.

190

A coupled mesoscale–microscale framework for wind resource estimation and farm aerodynamics  

Science Journals Connector (OSTI)

Abstract This study discusses the development of a coupled mesoscale–microscale framework for wind resource estimation and farm aerodynamics. WINDWYO is a computational framework for performing coupled mesoscale–microscale simulations. The framework is modular, automated and supports coupling of different mesoscale and microscale solvers using overset or matched grids. The modular nature of the framework and the support for overset grids allows the independent development of mesoscale and microscale solvers and the efficient coupling between the codes. The performance of the framework is evaluated by coupling Weather Research and Forecasting (WRF) model with three microscale computational fluid dynamics (CFD) codes of varying complexity. The solvers used are: (i) UWake: a blade element model with free-vortex wake, (ii) Flowyo: large eddy simulation code with actuator line/disk parametrization of the wind turbine and (iii) HELIOS: detached eddy simulation code with full rotor modeling and adaptive mesh refinement. Power predictions and wake visualization of single turbine and off-shore Lillgrund wind farm in uniform and turbulent inflow are used to demonstrate the capabilities of the framework.

Harish Gopalan; Christopher Gundling; Kevin Brown; Beatrice Roget; Jayanarayanan Sitaraman; Jefferey D. Mirocha; Wayne O. Miller

2014-01-01T23:59:59.000Z

191

Temporal Changes in Wind as Objects for Evaluating Mesoscale Numerical Weather Prediction  

E-Print Network [OSTI]

a method of evaluating numerical weather prediction models by comparing the characteristics of temporal for biases in features forecast by the model. 1. Introduction Verification of numerical weather predictionTemporal Changes in Wind as Objects for Evaluating Mesoscale Numerical Weather Prediction DARAN L

Knievel, Jason Clark

192

Modeling the Atmospheric Boundary Layer Wind Response to Mesoscale Sea Surface Temperature  

E-Print Network [OSTI]

(WRF) and COAMPS atmospheric models. The SST-induced wind response is assessed from eight simulations of the surface wind relative to the SST gradient. #12;3 1. Introduction Positive correlations of local surfaceModeling the Atmospheric Boundary Layer Wind Response to Mesoscale Sea Surface Temperature Natalie

Kurapov, Alexander

193

Propagation of Wind Energy into the Deep Ocean through a Fully Turbulent Mesoscale Eddy Field  

Science Journals Connector (OSTI)

The authors analyze the 3D propagation of wind-forced near-inertial motions in a fully turbulent mesoscale eddy field with a primitive equation numerical model. Although the wind stress is uniform, the near-inertial motion field quickly becomes ...

Eric Danioux; Patrice Klein; Pascal Rivière

2008-10-01T23:59:59.000Z

194

Field synergy principle analysis for reducing natural convection heat loss of a solar cavity receiver  

Science Journals Connector (OSTI)

Abstract Due to the operating temperature from 900 K to 1300 K produced by the concentrating ratio over 2000 in solar parabolic dish-engine system, the natural convection heat loss driven by the buoyancy force of air contributes an important role in the energy loss of cavity receiver. 3-D numerical simulations were performed and the results are analyzed from the novel viewpoint of field synergy principle (FSP) in order to study the heat transfer and fluid flow characteristics in natural convection heat loss of cavity receiver. The effects of geometric parameters, including the inclination angle, aperture size, aperture position and cavity geometric shape on the natural convection heat loss of cavity receiver were examined. The FSP analysis on the simulation results demonstrates that FSP can well explain the reduction mechanism for natural convection heat loss of cavity receiver because the smaller inner production of velocity vector and temperature gradient always corresponds to the lower Nusselt number occurred in the cases with lager inclination angle, smaller aperture size, lower aperture position and frustum-cylinder cavity, respectively. Therefore, the reducing natural convection heat loss attributes to the weakening synergy between velocity vector and temperature gradient. In addition, the local heat transfer performance is studied by the presented distributions of heat transferred via fluid motion, where more interesting natural convection heat loss characteristics of cavity receiver and the detailed explanations were provided. The results of this work offer benefits for the development of theory and technique about reducing natural convection heat loss of cavity receiver.

Yuqiang Li; Gang Liu; Zhenghua Rao; Shengming Liao

2015-01-01T23:59:59.000Z

195

Development of Ensemble Neural Network Convection Parameterizations for Climate Models  

SciTech Connect (OSTI)

The novel neural network (NN) approach has been formulated and used for development of a NN ensemble stochastic convection parametrization for climate models. This fast parametrization is built based on data from Cloud Resolving Model (CRM) simulations initialized with and forced by TOGA-COARE data. The SAM (System for Atmospheric Modeling), developed by D. Randall, M. Khairoutdinov, and their collaborators, has been used for CRM simulations. The observational data are also used for validation of model simulations. The SAM-simulated data have been averaged and projected onto the GCM space of atmospheric states to implicitly define a stochastic convection parametrization. This parametrization is emulated using an ensemble of NNs. An ensemble of NNs with different NN parameters has been trained and tested. The inherent uncertainty of the stochastic convection parametrization derived in such a way is estimated. Due to these inherent uncertainties, NN ensemble is used to constitute a stochastic NN convection parametrization. The developed NN convection parametrization have been validated in a diagnostic CAM (CAM-NN) run vs. the control CAM run. Actually, CAM inputs have been used, at every time step of the control/original CAM integration, for parallel calculations of the NN convection parametrization (CAM-NN) to produce its outputs as a diagnostic byproduct. Total precipitation (P) and cloudiness (CLD) time series, diurnal cycles, and P and CLD distributions for the large Tropical Pacific Ocean for the parallel CAM-NN and CAM runs show similarity and consistency with the NCEP reanalysis. The P and CLD distributions for the tropical area for the parallel runs have been analyzed first for the TOGA-COARE boreal winter season (November 1992 through February 1993) and then for the winter seasons of the follow-up parallel decadal simulations. The obtained results are encouraging and practically meaningful. They show the validity of the NN approach. This constitutes an important practical conclusion of the study: the obtained results on NN ensembles as a stochastic physics parametrization show a realistic possibility of development of NN convection parametrization for climate (and NWP) models based on learning cloud physics from CRM/SAM simulated data.

Fox-Rabinovitz, M. S.; Krasnopolsky, V. M.

2012-05-02T23:59:59.000Z

196

Section 12  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

A Mesoscale Convective System Parameterization Scheme A Mesoscale Convective System Parameterization Scheme for Use in General Circulation Models W. R. Cotton, G. D. Alexander, H. Jiang Colorado State University Fort Collins, Colorado Cloud-resolving simulations of mesoscale convective systems these simulations focuses on conditional sampling of the (MCS) have been used to build a parameterization scheme of stratiform region of each system. The conditional sampling of the thermodynamic forcing by the mesoscale flow branches of the fine grid data attempts to identify mesoscale updrafts and MCSs in models with resolution too coarse to resolve these mesoscale downdrafts within the stratiform region of each flow branches. This thermodynamic portion of the system. The thermodynamic part of the scheme is tested by

197

Realistic Solar Convection Simulations Robert F. Stein  

E-Print Network [OSTI]

Realistic Solar Convection Simulations Robert F. Stein Michigan State University, East Lansing, MIAFG, Juliane Maries Vej 30, Dk­2100 Copenhagen �, Denmark Abstract. We report on realistic simulations of solar and intensity spectra, the p­mode excitation rate, and the depth of the convection zone. We describe how solar

Stein, Robert

198

ARM - Field Campaign - ARM Support for the Plains Elevated Convection...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

convection, and (d) this lack of understanding greatly hampers the ability of numerical weather and climate models to simulate nocturnal convection well which leads to...

199

Coupling a Mesoscale Numerical Weather Prediction Model with Large-Eddy Simulation for Realistic Wind Plant Aerodynamics Simulations (Poster)  

SciTech Connect (OSTI)

Wind plant aerodynamics are influenced by a combination of microscale and mesoscale phenomena. Incorporating mesoscale atmospheric forcing (e.g., diurnal cycles and frontal passages) into wind plant simulations can lead to a more accurate representation of microscale flows, aerodynamics, and wind turbine/plant performance. Our goal is to couple a numerical weather prediction model that can represent mesoscale flow [specifically the Weather Research and Forecasting model] with a microscale LES model (OpenFOAM) that can predict microscale turbulence and wake losses.

Draxl, C.; Churchfield, M.; Mirocha, J.; Lee, S.; Lundquist, J.; Michalakes, J.; Moriarty, P.; Purkayastha, A.; Sprague, M.; Vanderwende, B.

2014-06-01T23:59:59.000Z

200

Non-Boussinesq effects in free thermal convection  

Science Journals Connector (OSTI)

Non-Boussinesq effects in a Rayleigh-Bénard convection system lead to a symmetry breaking between the top and the bottom boundary layers. We have found that the two layers adjust their temperature drops and the thicknesses ? such that their temperature scales ??/g??3 are equal, where ? is the thermal expansion coefficient, g is the gravitational acceleration, and ? and ? are the kinematic viscosity and thermal diffusivity, respectively.

Xiao-Zhong Wu and Albert Libchaber

1991-03-15T23:59:59.000Z

Note: This page contains sample records for the topic "mesoscale convective systems" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

A Climatological Study of Boundary Layer Wind Speed Using a Meso-?-Scale Higher-Order Closure Model  

Science Journals Connector (OSTI)

A mesoscale higher-order closure atmospheric boundary layer model has been used to get more detailed information than is possible from observations regarding horizontal and vertical variations of the wind in an area in southeastern Sweden. To ...

Hans Bergström

1996-08-01T23:59:59.000Z

202

Resolved Turbulence Characteristics in Large-Eddy Simulations Nested within Mesoscale Simulations Using the Weather Research and Forecasting Model  

Science Journals Connector (OSTI)

One-way concurrent nesting within the Weather Research and Forecasting Model (WRF) is examined for conducting large-eddy simulations (LES) nested within mesoscale simulations. Wind speed, spectra, and resolved turbulent stresses and turbulence ...

Jeff Mirocha; Branko Kosovi?; Gokhan Kirkil

2014-02-01T23:59:59.000Z

203

Using stochastic analysis to capture unstable equilibrium in natural convection  

SciTech Connect (OSTI)

A stabilized stochastic finite element implementation for the natural convection system of equations under Boussinesq assumptions with uncertainty in inputs is considered. The stabilized formulations are derived using the variational multiscale framework assuming a one-step trapezoidal time integration rule. The stabilization parameters are shown to be functions of the time-step size. Provision is made for explicit tracking of the subgrid-scale solution through time. A support-space/stochastic Galerkin approach and the generalized polynomial chaos expansion (GPCE) approach are considered for input-output uncertainty representation. Stochastic versions of standard Rayleigh-Benard convection problems are used to evaluate the approach. It is shown that for simulations around critical points, the GPCE approach fails to capture the highly non-linear input uncertainty propagation whereas the support-space approach gives fairly accurate results. A summary of the results and findings is provided.

Asokan, Badrinarayanan Velamur [Materials Process Design and Control Laboratory, Sibley School of Mechanical and Aerospace Engineering, 188 Frank H.T. Rhodes Hall, Cornell University, Ithaca, NY 14853-3801 (United States); Zabaras, Nicholas [Materials Process Design and Control Laboratory, Sibley School of Mechanical and Aerospace Engineering, 188 Frank H.T. Rhodes Hall, Cornell University, Ithaca, NY 14853-3801 (United States)]. E-mail: zabaras@cornell.edu

2005-09-01T23:59:59.000Z

204

CATHARE calculations of Phenix ultimate natural convection test  

SciTech Connect (OSTI)

The Phenix Sodium cooled Fast Reactor (SFR) started operation in 1973 and it was stopped in 2009. Before the reactor was definitively shutdown, in order to collect experimental data for code assessments in the frame of Generation IV an intensive program of ultimate tests was set up. Among these ultimate experiments, two thermal hydraulic tests were performed: an asymmetrical test consisting in a trip on one secondary pump and a natural convection test in the primary circuit. The natural convection test has been used for an international benchmark on system codes in the frame of the IAEA. The CATHARE code - initially developed for water cooled reactors and now extended for safety analyses for other kinds of reactors, including Sodium Fast Reactor - was used by CEA for this benchmark. The paper reminds briefly the Phenix reactor with the main physical parameters and the instrumentation used during the natural convection test. Main test results are also briefly reminded including the evolution of the core and the heat exchangers inlet and outlet temperatures, and some local temperature measurements. The main developments to perform CATHARE SFR computations and the strategy of system code assessment are presented. Then the CATHARE modelling of Phenix reactor is depicted and the various assumptions are pointed out. CATHARE encountered no problem to predict the initial nominal state. Afterwards, the whole transient scenario is calculated and CATHARE calculations are compared to the Phenix measurements. The global trend is rather well predicted by the CATHARE code. Nevertheless, due to complex flow phenomena occurring in large plena and components, the system code encountered physical limitations, leading to remaining discrepancies between code prediction and plant data. Various sensitivity calculations are presented and they bring partial answers. Additional analyses are in progress to understand more deeply the complex 3D phenomena involved during the different phases of the natural convection test. Additional work for coupling CATHARE system code and TRIO-U CFD code is in progress and will bring useful information to better understand the physical phenomena involved during the natural convection test and to improve system modeling for future SFR safety analysis. (authors)

Pialla, D.; Tenchine, D. [CEA, DEN, DM2S/STMF, Grenoble, F-17 rue des Martyrs, 38000 Grenoble (France); Gauthe, P. [CEA, DEN, DER/SESI, Cadarache, F-13108 Saint Paul lez Durance (France); Vasile, A. [CEA, DEN, DER, Cadarache, F-13108 Saint Paul lez Durance (France)

2012-07-01T23:59:59.000Z

205

Convective Cooling and Passive Stack Improvements in Motors (Presentation)  

SciTech Connect (OSTI)

This presentation discusses current research at NREL in convective cooling and passive stack improvements in motors.

Bennion, K.

2014-06-01T23:59:59.000Z

206

Heat Transport by Turbulent Rayleigh-Benard Convection  

SciTech Connect (OSTI)

We have developed a research program dedicated to the quantitative laboratory study of turbulent convection.

None

2008-10-03T23:59:59.000Z

207

Steady, three-dimensional, internally heated convection  

SciTech Connect (OSTI)

Numerical calculations have been carried out of steady, symmetric, three-dimensional modes of convection in internally heated, infinite Prandtl number, Boussinesq fluids at a Rayleigh number of 1.4[times]10[sup 4] in a spherical shell with inner/outer radius of 0.55 and in a 3[times]3[times]1 rectangular box. Multiple patterns of convection occur in both geometries. In the Cartesian geometry the patterns are dominated by cylindrical cold downflows and a broad hot upwelling. In the spherical geometry the patterns consist of cylindrical cold downwellings centered either at the vertices of a tetrahedron or the centers of the faces of a cube. The cold downflow cylinders are immersed in a background of upwelling within which there are cylindrical hot concentrations (plumes) and hot halos around the downflows. The forced hot upflow return plumes of internally heated spherical convection are fundamentally different from the buoyancy-driven plumes of heated from below convection.

Schubert, G. (Department of Earth and Space Sciences and Institute of Geophysics and Planetary Physics, University of California, Los Angeles, California 90024 (United States)); Glatzmaier, G.A.; Travis, B. (Earth and Environmental Sciences, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States))

1993-08-01T23:59:59.000Z

208

Modeling convection in the Greenland Sea  

E-Print Network [OSTI]

A detailed examination of the development of a deep convection event observed in the Greenland Sea in 1988-89 is carried out through a combination of modeling, scale estimates, and data analysis. We develop a prognostic ...

Bhushan, Vikas

1998-01-01T23:59:59.000Z

209

Observations on Buoyant Convection in Reverse Osmosis  

Science Journals Connector (OSTI)

Observations on Buoyant Convection in Reverse Osmosis ... Buoyancy Effects in Dead-End Reverse Osmosis:? Visualization by Holographic Interferometry ... Buoyancy Effects in Dead-End Reverse Osmosis:? Visualization by Holographic Interferometry ...

Terry J. Hendricks; Jean F. Macquin; Forman A. Williams

1972-05-01T23:59:59.000Z

210

Circulation and convection in the Irminger Sea  

E-Print Network [OSTI]

Aspects of the circulation and convection in the Irminger Sea are investigated using a variety of in-situ, satellite, and atmospheric reanalysis products. Westerly Greenland tip jet events are intense, small-scale wind ...

Våge, Kjetil

2010-01-01T23:59:59.000Z

211

An investigation of the rainfall distribution of a mesoscale network in Ecuador  

E-Print Network [OSTI]

provides a preliminary investigation of the mesoscale rainfall distribution of two geographical areas. The spatial distribution of rainfall at San Carlos, Ecuador, is compared with the spatial distribution at Riesel, Texas. This study is based upon..., 1964) at San Carlos and the daily rainfall of the 1960-1964 warm seasons (May through September) at Riesel. The isohyetal patterns and the depth-area relations show that rainfall often varies greatly over short dis- tances. A relationship exists...

Guest, Tommy Dean

2012-06-07T23:59:59.000Z

212

Dynamic Transitions of Surface Tension Driven Convection  

E-Print Network [OSTI]

We study the well-posedness and dynamic transitions of the surface tension driven convection in a three-dimensional (3D) rectangular box with non-deformable upper surface and with free-slip boundary conditions. It is shown that as the Marangoni number crosses the critical threshold, the system always undergoes a dynamic transition. In particular, two different scenarios are studied. In the first scenario, a single mode losing its stability at the critical parameter gives rise to either a Type-I (continuous) or a Type-II (jump) transition. The type of transitions is dictated by the sign of a computable non-dimensional parameter, and the numerical computation of this parameter suggests that a Type-I transition is favorable. The second scenario deals with the case where the geometry of the domain allows two critical modes which possibly characterize a hexagonal pattern. In this case we show that the transition can only be either a Type-II or a Type-III (mixed) transition depending on another computable non-dimensional parameter. We only encountered Type-III transition in our numerical calculations. The second part of the paper deals with the well-posedness and existence of global attractors for the problem.

Henk Dijkstra; Taylan Sengul; Shouhong Wang

2011-05-05T23:59:59.000Z

213

ThermalEngineeringLaboratory,VanderbiltUniversity Convection Heat Transfer of Nanofluids in Commercial  

E-Print Network [OSTI]

in Commercial Electronic Cooling Systems N.A. Roberts and D.G. Walker Department of Mechanical Engineering in real systems · Benefits of nanofluids ­ reduced sedimentation and viscosity ­ reduced damageThermalEngineeringLaboratory,VanderbiltUniversity Convection Heat Transfer of Nanofluids

Walker, D. Greg

214

Convection in magnetic fluids with internal heat generation  

SciTech Connect (OSTI)

The effect of a uniform distribution of heat source on the onset of stationary convection in a horizontal Boussinesq magnetic fluid layer bounded by isothermal nonmagnetic boundary is investigated. Solutions are obtained using a higher order Galerkin expansion technique, considering different isothermal boundary combinations (rigid-rigid, rigid-free, and free-free). It is found that the effect of internal magnetic number, due to a heat source, is to make the system more unstable. The results obtained, in the limiting cases, compare well with the existing literature.

Rudraiah, N.; Sekhar, G.N. (Bangalore Univ. (India))

1991-02-01T23:59:59.000Z

215

Defect Chaos of Oscillating Hexagons in Rotating Convection  

SciTech Connect (OSTI)

Using coupled Ginzburg-Landau equations, the dynamics of hexagonal patterns with broken chiral symmetry are investigated, as they appear in rotating non-Boussinesq or surface-tension-driven convection. We find that close to the secondary Hopf bifurcation to oscillating hexagons the dynamics are well described by a single complex Ginzburg-Landau equation (CGLE) coupled to the phases of the hexagonal pattern. At the band center these equations reduce to the usual CGLE and the system exhibits defect chaos. Away from the band center a transition to a frozen vortex state is found. (c) 2000 The American Physical Society.

Echebarria, Blas; Riecke, Hermann

2000-05-22T23:59:59.000Z

216

Granular fountains: Convection cascade in a compartmentalized granular gas  

Science Journals Connector (OSTI)

This paper extends the two-compartment granular fountain [D. van der Meer, P. Reimann, K. van der Weele, and D. Lohse, Phys. Rev. Lett. 92, 184301 (2004)] to an arbitrary number of compartments: The tendency of a granular gas to form clusters is exploited to generate spontaneous convective currents, with particles going down in the well-filled compartments and going up in the diluted ones. We focus upon the bifurcation diagram of the general K-compartment system, which is constructed using a dynamical flux model and which proves to agree quantitatively with results from molecular dynamics simulations.

Devaraj van der Meer; Ko van der Weele; Peter Reimann

2006-06-22T23:59:59.000Z

217

Origins of convective activity over Panama  

E-Print Network [OSTI]

Satellite-derived outgoing longwave radiation (OLR) data. were used to examine convective variability over the Panama region. Time series analysis of the area- averaged daily OLR data, for 1984 and 1985 revealed a, persistent 12-d oscillation... in convective activity during each season. Composite analyses of OLR data, for the area 120'W-40'W and 35'S-35'N for the 1984 dry (1 January ? 9 May) and wet (10 Msy? 4 December) seasons showed this oscillation extends beyond Panama and the Central America...

Strager, Christopher Stephen

1989-01-01T23:59:59.000Z

218

Triggering Deep Convection with a Probabilistic Plume Model  

Science Journals Connector (OSTI)

A model unifying the representation of the planetary boundary layer and dry, shallow, and deep convection, the probabilistic plume model (PPM), is presented. Its capacity to reproduce the triggering of deep convection over land is analyzed in ...

Fabio D’Andrea; Pierre Gentine; Alan K. Betts; Benjamin R. Lintner

2014-11-01T23:59:59.000Z

219

Heat Transfer by Free Convection in a Liquid Metal  

Science Journals Connector (OSTI)

19 December 1961 research-article Heat Transfer by Free Convection in a Liquid Metal F. J. Bayley...an experimental investigation of the free convection heat transfer process under the special conditions associated with...

1961-01-01T23:59:59.000Z

220

A Moisture-Stratiform Instability for Convectively Coupled Waves  

Science Journals Connector (OSTI)

A simple model of two vertical modes is constructed and analyzed to reveal the basic instability mechanisms of convectively coupled waves. The main novelty of this model is a convective parameterization based on the quasi-equilibrium concept and ...

Zhiming Kuang

2008-03-01T23:59:59.000Z

Note: This page contains sample records for the topic "mesoscale convective systems" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

Radiative–Convective Equilibrium over a Land Surface  

Science Journals Connector (OSTI)

Radiative–convective equilibrium (RCE) describes an idealized state of the atmosphere in which the vertical temperature profile is determined by a balance between radiative and convective fluxes. While RCE has been applied extensively over oceans, ...

Nicolas Rochetin; Benjamin R. Lintner; Kirsten L. Findell; Adam H. Sobel; Pierre Gentine

2014-12-01T23:59:59.000Z

222

Nesting large-eddy simulations within mesoscale simulations for wind energy applications  

SciTech Connect (OSTI)

With increasing demand for more accurate atmospheric simulations for wind turbine micrositing, for operational wind power forecasting, and for more reliable turbine design, simulations of atmospheric flow with resolution of tens of meters or higher are required. These time-dependent large-eddy simulations (LES), which resolve individual atmospheric eddies on length scales smaller than turbine blades and account for complex terrain, are possible with a range of commercial and open-source software, including the Weather Research and Forecasting (WRF) model. In addition to 'local' sources of turbulence within an LES domain, changing weather conditions outside the domain can also affect flow, suggesting that a mesoscale model provide boundary conditions to the large-eddy simulations. Nesting a large-eddy simulation within a mesoscale model requires nuanced representations of turbulence. Our group has improved the Weather and Research Forecasting model's (WRF) LES capability by implementing the Nonlinear Backscatter and Anisotropy (NBA) subfilter stress model following Kosovic (1997) and an explicit filtering and reconstruction technique to compute the Resolvable Subfilter-Scale (RSFS) stresses (following Chow et al, 2005). We have also implemented an immersed boundary method (IBM) in WRF to accommodate complex terrain. These new models improve WRF's LES capabilities over complex terrain and in stable atmospheric conditions. We demonstrate approaches to nesting LES within a mesoscale simulation for farms of wind turbines in hilly regions. Results are sensitive to the nesting method, indicating that care must be taken to provide appropriate boundary conditions, and to allow adequate spin-up of turbulence in the LES domain.

Lundquist, J K; Mirocha, J D; Chow, F K; Kosovic, B; Lundquist, K A

2008-09-08T23:59:59.000Z

223

The Convective Instability Pathway to Warm Season Drought in Texas. Part II: Free-Tropospheric Modulation of Convective Inhibition  

Science Journals Connector (OSTI)

This study is concerned with the modulation by convective instability of summertime precipitation in Texas as a mechanism for maintaining or enhancing drought. The important role of convective inhibition (CIN), its dependence on the temperature ...

Boksoon Myoung; John W. Nielsen-Gammon

2010-09-01T23:59:59.000Z

224

Turbulent convection in liquid metal with and without rotation  

E-Print Network [OSTI]

is the efficiency of convective heat transfer (Nu). In general, we find that the convective behavior of liquid metal=ðkT�, where q is total heat flux and k is the fluid's thermal conductivity. Heat flux q is total heat power P by turbulent, rotating convection in liquid metal. Liquid metals are peculiar in that they diffuse heat more

225

Realistic Solar Surface Convection Simulations Robert F. Stein  

E-Print Network [OSTI]

Realistic Solar Surface Convection Simulations Robert F. Stein Michigan State University, East free simulations with re­ alistic physics of convection near the solar surface. We summarize solar convection is non­local. It is driven from a thin surface thermal boundary layer where radiative

Stein, Robert

226

Testing turbulent convection theory in solar models – I. Structure of the solar convection zone  

Science Journals Connector (OSTI)

......outer envelope of the Sun, low-temperature opacities from Alexander...SSM. Fig. 9 shows the distribution of the temperature gradient in the solar...on the structure of the Sun, especially the temperature gradient in the convection......

Y. Li; J. Y. Yang

2007-02-11T23:59:59.000Z

227

Solar MagnetoConvection David J. Bercik  

E-Print Network [OSTI]

Solar Magneto­Convection David J. Bercik Dept. of Physics and Astronomy, Michigan State University, Michigan State University, East Lansing, MI 48824, U.S.A. š Ake Nordlund Theoretical Astrophysics Center, �ster Voldgade 3, 1350 Copenhagen K, Denmark Robert F. Stein Dept. of Physics and Astronomy, Michigan

Stein, Robert

228

Mantle Convection with Strong Subduction Zones  

E-Print Network [OSTI]

of the oceanic lithosphere within a small region of a nite element grid. By imposing velocity boundary conditions thermal structure. To make the model dynamically consistent, we specify a rate for subduction that balances the energy budget for convection, which includes an expression for the energy needed to bend

Conrad, Clint

229

Non-Boussinesq rolls in 2d thermal convection  

Science Journals Connector (OSTI)

Abstract A study of convection in a circular two dimensional cell is presented. The system is heated and cooled at two diametrically opposed points on the edge of the circle, which are parallel or anti-parallel to gravity. The latter’s role in the plane of the cell can be changed by tilting the cell. When the system is in a horizontal position, a non-trivial analytic solution for the temperature distribution of the quiescent fluid can be found. For a slight inclination, the projection of gravity in the plane of the cell is used as a perturbation parameter in the full hydrodynamic description, as the Boussinesq approximation is unjustified. To first order, the equations are solved for the stationary case and four symmetrical rolls become apparent, showing that a purely conductive state is impossible if gravity–however small–is present; an approximate closed analytical expression is obtained, which describes the four convection rolls. Further analysis is done by a direct numerical integration. Comparison with preliminary observations is mentioned.

C. Málaga; F. Mandujano; R. Peralta-Fabi; C. Arzate

2015-01-01T23:59:59.000Z

230

Non-Boussinesq Rolls in 2d Thermal Convection  

E-Print Network [OSTI]

A study of convection in a circular two dimensional cell is presented. The system is heated and cooled at two diametrically opposed points on the edge of the circle, which are parallel or anti-parallel to gravity. The latter's role in the plane of the cell can be changed by tilting the cell. When the system is in a horizontal position, a non-trivial analytic solution for the temperature distribution of the quiescent fluid can be found. For a slight inclination, the projection of gravity in the plane of the cell is used as a perturbation parameter in the full hydrodynamic description, as the Boussinesq approximation is inadequate. To first order, the equations are solved for the stationary case and four symmetrical rolls become apparent, showing that a purely conductive state is impossible if gravity -however small- is present; an approximate closed analytical expression is obtained, which describes the four convection rolls. Further analysis is done by a direct numerical integration. Comparison with prelimina...

Málaga, C; Peralta-Fabi, R; Arzate, C

2013-01-01T23:59:59.000Z

231

EulerianEulerian two-phase numerical simulation of nanofluid laminar forced convection in a microchannel  

E-Print Network [OSTI]

by a cooling system to guarantee their appropriate performance. One possible way to cool these devises canEulerian­Eulerian two-phase numerical simulation of nanofluid laminar forced convection August 2010 Accepted 5 August 2010 Keywords: Nanofluid Microchannel Two-phase Laminar Heat transfer a b

Harting, Jens

232

Morphology, Intensity, and Rainfall Production of MJO Convection: Observations from DYNAMO Shipborne Radar and TRMM  

Science Journals Connector (OSTI)

This study uses DYNAMO shipborne (R/V Revelle) radar and TRMM Precipitation Radar (PR) datasets to investigate MJO-associated convective systems in specific organizational modes (MCS vs. sub-MCS, linear vs. non-linear). The Revelle radar sampled ...

Weixin Xu; Steven A. Rutledge

233

High-latitude ionospheric convection models derived from Defense Meteorological Satellite Program ion drift  

E-Print Network [OSTI]

Vladimir O. Papitashvili Space Physics Research Laboratory, University of Michigan, Ann Arbor, Michigan to the average solar wind (i.e., the ``quasi-viscous'' interaction) and to changes in the IMF By, Bz 0, and Bz, plasma convection, current systems 1. Introduction [2] Earth's magnetosphere is immersed in the solar

Michigan, University of

234

Relationships between lightning and properties of convective cloud Joanna M. Futyan1,2  

E-Print Network [OSTI]

August 2007. [1] Satellite observations of convective system properties and lightning flash rate are used with the lightning flash rate. A roughly second order power-law fit to the mean radar echo top height above the 0°C isotherm is shown to capture both regional and land-ocean contrasts in lightning occurrence and flash rate

235

Numerical Simulation of the Meso-? Scale Structure and Evolution of the 1977 Johnstown Flood. Part I: Model Description and Verification  

Science Journals Connector (OSTI)

The Pennsylvania State University/NCAR mesoscale model, originally developed by Anthes and Warner, is modified to simulate the meso-? scale structure and evolution of convectively driven weather systems. The modifications include: (i) two-way ...

Da-Lin Zhang; J. Michael Fritsch

1986-09-01T23:59:59.000Z

236

Transport Processes in the Tropical Warm Pool Boundary Layer. Part II: Vertical Structure and Variability  

Science Journals Connector (OSTI)

The structure of the intertropical convergence zone ITCZ cloud-topped marine atmospheric boundary layer away from the most intense mesoscale convective systems during the Tropical Ocean Global Atmosphere Coupled Ocean–Atmosphere Response ...

A. G. Williams; J. M. Hacker; H. Kraus

1997-08-01T23:59:59.000Z

237

Convective equilibrium and mixing-length theory for stellarator reactors  

SciTech Connect (OSTI)

In high ..beta.. stellarator and tokamak reactors, the plasma pressure gradient in some regions of the plasma may exceed the critical pressure gradient set by ballooning instabilities. In these regions, convective cells break out to enhance the transport. As a result, the pressure gradient can rise only slightly above the critical gradient and the plasma is in another state of equilibrium - ''convective equilibrium'' - in these regions. Although the convective transport cannot be calculated precisely, it is shown that the density and temperature profiles in the convective region can still be estimated. A simple mixing-length theory, similar to that used for convection in stellar interiors, is introduced in this paper to provide a qualitative description of the convective cells and to show that the convective transport is highly efficient. A numerical example for obtaining the density and temperature profiles in a stellarator reactor is given.

Ho, D.D.M.; Kulsrud, R.M.

1985-09-01T23:59:59.000Z

238

The Surface Expression of Semidiurnal Internal Tides near a Strong Source at Hawaii. Part II: Interactions with Mesoscale Currents*  

E-Print Network [OSTI]

: the cyclone causes the energy of internal tide rays propagating through its core to increase near the surface with astronomical forcing because of the presence of mesoscale variability. Internal tide energy is mainly affected but not negligible role, inducing energy transfers between the internal tides and background currents. Furthermore

239

Tests of an Ensemble Kalman Filter for Mesoscale and Regional-Scale Data Assimilation. Part II: Imperfect Model Experiments  

E-Print Network [OSTI]

degraded). As in Part I, where the perfect model assumption was utilized, most analysis error reduction of significant model errors due to physical parameterizations by assimilating synthetic sounding and surfaceTests of an Ensemble Kalman Filter for Mesoscale and Regional-Scale Data Assimilation. Part II

Meng, Zhiyong

240

Mesoscale Self-Assembly: Capillary Bonds and Negative Menisci Ned Bowden, Scott R. J. Oliver, and George M. Whitesides*  

E-Print Network [OSTI]

Mesoscale Self-Assembly: Capillary Bonds and Negative Menisci Ned Bowden, Scott R. J. Oliver., Cambridge, Massachusetts 02138 ReceiVed: September 2, 1999 This paper describes the self-assembly) that examined the self-assembly of hexagonal plates of PDMS (F ) 1.05 g/cm3) that had a density close

Prentiss, Mara

Note: This page contains sample records for the topic "mesoscale convective systems" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

Argonne National Laboratory's Natural Convection  

E-Print Network [OSTI]

in large-scale thermal hydraulics facilities. This helps validate advanced simulation tools such as those power. The diagram to the left shows the scaling basis for the NSTF. First, a full-scale nuclear plant Electric's Power Reactor Innovative Small Module (PRISM) Reactor Vessel Auxiliary Cooling System (RVACS

Kemner, Ken

242

Special session: computational predictability of natural convection flows in enclosures  

SciTech Connect (OSTI)

Modern thermal design practices often rely on a ''predictive'' simulation capability--although predictability is rarely quantified and often difficult to confidently achieve in practice. The computational predictability of natural convection in enclosures is a significant issue for many industrial thermal design problems. One example of this is the design for mitigation of optical distortion due to buoyancy-driven flow in large-scale laser systems. In many instances the sensitivity of buoyancy-driven enclosure flows can be linked to the presence of multiple bifurcation points that yield laminar thermal convective processes that transition from steady to various modes of unsteady flow. This behavior is brought to light by a problem as ''simple'' as a differentially-heated tall rectangular cavity (8:1 height/width aspect ratio) filled with a Boussinesq fluid with Pr = 0.71--which defines, at least partially, the focus of this special session. For our purposes, the differentially-heated cavity provides a virtual fluid dynamics laboratory.

Christon, M A; Gresho, P M; Sutton, S B

2000-08-14T23:59:59.000Z

243

ON THE PENETRATION OF MERIDIONAL CIRCULATION BELOW THE SOLAR CONVECTION ZONE. II. MODELS WITH CONVECTION ZONE, THE TAYLOR-PROUDMAN CONSTRAINT, AND APPLICATIONS TO OTHER STARS  

SciTech Connect (OSTI)

The solar convection zone exhibits a strong level of differential rotation, whereby the rotation period of the polar regions is about 25%-30% longer than the equatorial regions. The Coriolis force associated with these zonal flows perpetually 'pumps' the convection zone fluid, and maintains a quasi-steady circulation, poleward near the surface. What is the influence of this meridional circulation on the underlying radiative zone, and in particular, does it provide a significant source of mixing between the two regions? In Paper I, we began to study this question by assuming a fixed meridional flow pattern in the convection zone and calculating its penetration depth into the radiative zone. We found that the amount of mixing caused depends very sensitively on the assumed flow structure near the radiative-convective interface. We continue this hydrodynamic study here by including a simple model for the convection zone 'pump', and calculating in a self-consistent manner the meridional flows generated in the whole Sun. We find that the global circulation timescale depends in a crucial way on two factors: the overall stratification of the radiative zone as measured by the square root of the Prandtl number times the ratio of the Brunt-Vaeisaelae frequency to the rotation rate, and, for weakly stratified systems, the presence or absence of stresses within the radiative zone capable of breaking the Taylor-Proudman constraint. We conclude by discussing the consequences of our findings for the solar interior and argue that a potentially important mechanism for mixing in young main-sequence stars has so far been neglected.

Garaud, P.; Acevedo Arreguin, L. [Department of Applied Mathematics and Statistics, Baskin School of Engineering, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 (United States)

2009-10-10T23:59:59.000Z

244

Thermocapillary convection induced by laser surface heating  

SciTech Connect (OSTI)

Thermocapillary convection was excited by a laser source in experiments on molten paraffin. The parameters of the resultant flow were determined. The nature of the flow was demonstrated to correspond to shear-driven boundary-layer flow at high Reynolds numbers. Correlation dependences of the flow velocity of the melt and its temperature in the surface region were derived theoretically and were shown to agree with the experimental results. When the size of the laser spot was much less than the characteristic convection scales, three regions of flow of the melt could be distinguished: a viscous surface boundary layer, a stagnation zone under the laser spot, and a large-scale region of flow with a homogeneous temperature distribution. (interaction of laser radiation with matter. laser plasma)

Gladush, G G; Drobyazko, S V; Likhanskii, V V; Loboiko, A I; Senatorov, Yu M [State Research Center of Russian Federation 'Troitsk Institute for Innovation and Fusion Research', Troitsk, Moscow Region (Russian Federation)

1998-05-31T23:59:59.000Z

245

Analysis and design of the internal mass transfer in oxygen-hydrogen fuel cell with a capillary membrane and with convective drainage of vaporous reaction products  

Science Journals Connector (OSTI)

The mechanism of mass transfer is analyzed by which water vapor drains convectively from an electrode-condenser system in a fuel cell with a capillary membrane. The problem of optimizing the mass-transfer para...

V. N. Serebryakov; M. V. Mel'nikov; V. S. Ovchinnikov…

1973-01-01T23:59:59.000Z

246

ARM - Field Campaign - Midlatitude Continental Convective Clouds Experiment  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Experiment (MC3E) Experiment (MC3E) Campaign Links Science Plan MC3E Website Related Campaigns Midlatitude Continental Convective Clouds Experiment: 2DVD Support 2011.04.22, Schwaller, SGP Midlatitude Continental Convective Clouds Experiment (MC3E): Airborne Instruments 2011.04.22, Poellot, AAF Midlatitude Continental Convective Clouds Experiment (MC3E): Multi-Frequency Profilers 2011.04.22, Williams, SGP Midlatitude Continental Convective Clouds Experiment: Parsivel Disdrometer Support 2011.04.22, Schwaller, SGP Midlatitude Continental Convective Clouds Experiment (MC3E): Inner Domain Thermodynamic Profiling during MC3E 2011.04.22, Turner, SGP Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Campaign : Midlatitude Continental Convective Clouds Experiment (MC3E)

247

Meridional Circulation in Solar and Stellar Convection Zones  

E-Print Network [OSTI]

We present a series of 3-D nonlinear simulations of solar-like convection, carried out using the Anelastic Spherical Harmonic (ASH) code, that are designed to isolate those processes that drive and shape meridional circulations within stellar convection zones. These simulations have been constructed so as to span the transition between solar-like differential rotation (fast equator/slow poles) and ``anti-solar' differential rotation (slow equator/fast poles). Solar-like states of differential rotation, arising when convection is rotationally constrained, are characterized by a very different convective Reynolds stress than anti-solar regimes, wherein convection only weakly senses the Coriolis force. We find that the angular momentum transport by convective Reynolds stress plays a central role in establishing the meridional flow profiles in these simulations. We find that the transition from single-celled to multi-celled meridional circulation profiles in strong and weak regimes of rotational constraint is lin...

Featherstone, Nicholas A

2015-01-01T23:59:59.000Z

248

Sensitivity of the Simulated Distributions of Water Masses, CFCs, and Bomb 14C to Parameterizations of Mesoscale Tracer Transports in a Model of the North Pacific  

Science Journals Connector (OSTI)

A basinwide ocean general circulation model of the North Pacific Ocean is used to study the sensitivity of the simulated distributions of water masses, chlorofluorocarbons (CFCs), and bomb carbon-14 isotope (14C) to parameterizations of mesoscale ...

Yongfu Xu; Shigeaki Aoki; Koh Harada

2006-03-01T23:59:59.000Z

249

Improving an Accuracy of ANN-Based Mesoscale-Microscale Coupling Model by Data Categorization: With Application to Wind Forecast for Offshore and Complex Terrain Onshore Wind Farms  

Science Journals Connector (OSTI)

The ANN-based mesoscale-microscale coupling model forecasts wind speed and wind direction with high accuracy for wind parks located in complex terrain onshore, yet some weather regimes remains unresolved and f...

Alla Sapronova; Catherine Meissner…

2014-01-01T23:59:59.000Z

250

Tracer Gas Transport under Mixed Convection Conditions in an Experimental  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Tracer Gas Transport under Mixed Convection Conditions in an Experimental Tracer Gas Transport under Mixed Convection Conditions in an Experimental Atrium: Comparison Between Experiments and CFD Predictions Title Tracer Gas Transport under Mixed Convection Conditions in an Experimental Atrium: Comparison Between Experiments and CFD Predictions Publication Type Journal Article Year of Publication 2006 Authors Jayaraman, Buvaneswari, Elizabeth U. Finlayson, Michael D. Sohn, Tracy L. Thatcher, Phillip N. Price, Emily E. Wood, Richard G. Sextro, and Ashok J. Gadgil Journal Atmospheric Environment Volume 40 Start Page Chapter Pagination 5236-5250 Keywords airflow and pollutant transport group, atria, indoor airflow and pollutant transport, indoor environment department, indoor pollutant dispersion, mixed convection, turbulence model

251

Diurnal Cycle of Convection at the ARM SGP Site: Role of Large-Scale Forcing, Surface Fluxes, and Convective Inhibition  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Diurnal Cycle of Convection at the ARM SGP Site: Diurnal Cycle of Convection at the ARM SGP Site: Role of Large-Scale Forcing, Surface Fluxes, and Convective Inhibition G. J. Zhang Center for Atmospheric Sciences Scripps Institution of Oceanography La Jolla, California Introduction Atmospheric convection undergoes strong diurnal variation over both land and oceans (Gray and Jacobson 1977; Dai 2001; Nesbitt and Zipser 2003). Because of the nature of the diurnal variation of solar radiation, the phasing of convection with solar radiation has a significant impact on the atmospheric radiation budget and cloud radiative forcing. A number of studies have investigated the possible mechanisms of the diurnal variation of convection (Gray and Jacobson 1977; Randall et al. 1991; Dai et al. 1999; Dai 2001). Yet, in regional and global climate models, the diurnal variation of

252

A numerical investigation of natural convection heat transfer within horizontal spent-fuel assemblies  

SciTech Connect (OSTI)

A numerical investigation of natural convection heat transfer is carried out for a single, horizontal, spent-fuel assembly in an environment typical of spent-fuel transportation systems as well as some dry storage/disposal scenarios. The objective is to predict computationally the convective heat transfer trends for horizontal spent fuel and to compare the results to data taken in a supporting experimental effort. The predicted data consist of thermal and flow fields throughout the assembly for a wide range of Rayleigh number, as well as numerically obtained Nusselt-number data that are correlated as a function of Rayleigh number. Both laminar and turbulent approaches are examined for a Boussinesq fluid with Pr = 0.7. The data predict the existence of a conduction-dominated regime, a transition regime, and a convection regime. Compared with the laminar approach, a significant improvement in the predicted Nusselt number is obtained for large Rayleigh numbers when a turbulence model is employed. This lends additional support to the experimental evidence that a transition to turbulent flow occurs for Rayleigh numbers greater than 10{sup 7}. Overall, the numerically predicted heat transfer trends compare well with previously obtained experimental data, and the computed assembly Nusselt numbers generally reside within the range of experimental uncertainty. The predicted thermal and flow fields further provide a numerical flow visualization capability that enhances the understanding of natural convection in horizontal spent fuel and allows improved physical interpretation of the experimental data.

Canaan, R.E. [Lawrence Livermore National Lab., CA (United States); Klein, D.E. [Univ. of Texas System, Austin, TX (United States)

1998-08-01T23:59:59.000Z

253

What Goes Up Must Come Down: The Lifecycle of Convective Clouds (492nd Brookhaven Lecture)  

SciTech Connect (OSTI)

Some clouds look like cotton balls and others like anvils. Some bring rain, some snow and sleet, and others, just shade. But, whether big and billowy or dark and stormy, clouds affect far more than the weather each day. Armed with measurements of clouds’ updrafts and downdrafts—which resemble airflow in a convection oven—and many other atmospheric interactions, scientists from Brookhaven Lab and other institutions around the world are developing models that are crucial for understanding Earth’s climate and forecasting future climate change. During his lecture, Dr. Jensen provides an overview of the importance of clouds in the Earth’s climate system before explaining how convective clouds form, grow, and dissipate. His discussion includes findings from the Midlatitude Continental Convective Clouds Experiment (MC3E), a major collaborative experiment between U.S. Department of Energy (DOE) and NASA scientists to document precipitation, clouds, winds, and moisture in 3-D for a holistic view of convective clouds and their environment.

Jensen, Michael [BNL Environmental Sciences

2014-02-19T23:59:59.000Z

254

Internal wave generation by convection in water. Part 2. Numerical simulations  

E-Print Network [OSTI]

Water's density maximum at 4C makes it well suited to study internal gravity wave excitation by convection: an increasing temperature profile is unstable to convection below 4C, but stably stratified above 4C. We present numerical simulations of water near its density maximum in a two dimensional tank, similar to the experiment described in a companion paper (Le Bars et al. 2015). The simulations agree very well with the experiments, despite differences in lateral boundary conditions in the two systems. We successfully model the damping of waves in the simulations using linear theory, provided we do not take the weak damping limit typically used in the literature. In order to isolate the physical mechanism exciting internal waves, we use the novel spectral code Dedalus to run several simulations of the simulation. We use data from the full simulation as source terms in two simplified models of internal wave excitation by convection: bulk excitation by convective Reynolds stresses, and interface forcing via th...

Lecoanet, Daniel; Burns, Keaton J; Vasil, Geoffrey M; Brown, Benjamin P; Quataert, Eliot; Oishi, Jeffrey S

2014-01-01T23:59:59.000Z

255

Transitions between patterns in thermal convection  

SciTech Connect (OSTI)

We present experimental studies of the transitions between conduction, hexagons, and rolls in non-Boussinesq convection of gaseous CO{sub 2} in a cylindrical cell of radius-to-height ratio 86. Except for the transition from conduction to hexagons, transitions occur when the two states involved have nearly the same value of a generalized potential rather than at the stability limits. Conduction gives way to hexagons via the propagation of a front connecting the two states, while the transitions between hexagons and rolls are facilitated at the cell walls which appear to nucleate the minority state.

Bodenschatz, E.; de Bruyn, J.R.; Ahlers, G.; Cannell, D.S. (Department of Physics and Center for Nonlinear Science, University of California, Santa Barbara, Santa Barbara, California (USA) Memorial University of Newfoundland, St. John's, Newfoundland (Canada))

1991-11-25T23:59:59.000Z

256

TURBULENT MIXING AND LAYER FORMATION IN DOUBLE-DIFFUSIVE CONVECTION: THREE-DIMENSIONAL NUMERICAL SIMULATIONS AND THEORY  

SciTech Connect (OSTI)

Double-diffusive convection, often referred to as semi-convection in astrophysics, occurs in thermally and compositionally stratified systems which are stable according to the Ledoux criterion but unstable according to the Schwarzschild criterion. This process has been given relatively little attention so far, and its properties remain poorly constrained. In this paper, we present and analyze a set of three-dimensional simulations of this phenomenon in a Cartesian domain under the Boussinesq approximation. We find that in some cases the double-diffusive convection saturates into a state of homogeneous turbulence, but with turbulent fluxes several orders of magnitude smaller than those expected from direct overturning convection. In other cases, the system rapidly and spontaneously develops closely packed thermo-compositional layers, which later successively merge until a single layer is left. We compare the output of our simulations with an existing theory of layer formation in the oceanographic context and find very good agreement between the model and our results. The thermal and compositional mixing rates increase significantly during layer formation and increase even further with each merger. We find that the heat flux through the staircase is a simple function of the layer height. We conclude by proposing a new approach to studying transport by double-diffusive convection in astrophysics.

Rosenblum, E. [Department of Physics, Stony Brook University, Stony Brook, New York, NY 11794 (United States); Garaud, P.; Traxler, A. [Department of Applied Mathematics and Statistics, Baskin School of Engineering, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95064 (United States); Stellmach, S. [Institut fuer Geophysik, Westfaelische Wilhelms-Universitaet Muenster, Muenster D-48149 (Germany)

2011-04-10T23:59:59.000Z

257

Predicting free laminar convection heat transfer on curvilinear surfaces  

SciTech Connect (OSTI)

Free laminar convection on an isothermal surface of cylindrical and axisymmetric bodies of arbitrary cross section is considered in the Boussinesq approximation. The problem is solved by the method of generalized similarity in its local approximation. Universal formulae are obtained for calculating the local Nusselt number. Prediction of convection on a heated horizontal cylindrical and sphere are given as examples of the method.

Stepanyants, L.G.; Shelukho, S.I.

1989-07-01T23:59:59.000Z

258

EXPERIMENTAL INVESTIGATION OF BOILING HEAT CONVECTION IN A FRACTURE  

E-Print Network [OSTI]

EXPERIMENTAL INVESTIGATION OF BOILING HEAT CONVECTION IN A FRACTURE A REPORT SUBMITTED between heat conduction and heat convection with boiling flow in a rock fracture. An experimental coefficient. This coefficient is the proportionality factor between the heat flux to a fracture surface

Stanford University

259

Deep storage of oceanic crust in a vigorously convecting mantle  

E-Print Network [OSTI]

Deep storage of oceanic crust in a vigorously convecting mantle J. P. Brandenburg1 and P. E. van: Brandenburg, J. P., and P. E. van Keken (2007), Deep storage of oceanic crust in a vigorously convecting cycle of creation, interaction with seawater and subduction may be responsi- ble for the loss of Pb

van Keken, Peter

260

Theoretical analysis of convective heat transfer enhancement of microencapsulated phase change material slurries  

Science Journals Connector (OSTI)

...This paper analyzes the convective heat transfer enhancement mechanism of microencapsulated phase change material slurries based on the analogy between convective ... addition, the conventional Nusselt number ...

Yinping Zhang; Xianxu Hu; Xin Wang

2003-12-01T23:59:59.000Z

Note: This page contains sample records for the topic "mesoscale convective systems" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

Natural convection phenomena in a nuclear power plant during a postulated TMLB' accident  

SciTech Connect (OSTI)

After the TMI (Three Mile Island) accident, there has been significant interest in analyzing and understanding the phenomena that may occur in a PWR (Pressurized Water Reactor) accident which may lead to partial or total core meltdown and degradation. Natural convection is one of the important phenomena. In the present paper the results of two numerical simulations of (1) four-loop PWR and (2) three-loop PWR are presented. The simulations were performed with the COMMIX(2) computer code. Our analysis shows that in severe accident scenarios, natural convection phenomena does occur and that it helps to delay core degradation by transferring decay heat from the reactor core to other internal structures of the reactor system. The amount of heat transfer and delay in core degradation depends on the geometry and internal structures of the system and on the events of an accident.

Domanus, H.M.; Schmitt, R.C.; Sha, W.T.; Shah, V.L.; Han, J.T.

1987-01-01T23:59:59.000Z

262

Mesoscale Data Assimilation for a Local Severe Rainfall Event with the NHM–LETKF System  

Science Journals Connector (OSTI)

This study seeks to improve forecasts of local severe weather events through data assimilation and ensemble forecasting approaches using the local ensemble transform Kalman filter (LETKF) implemented with the Japan Meteorological Agency’s ...

Masaru Kunii

2014-10-01T23:59:59.000Z

263

A numerical study of the mesoscale eddy dynamics of the Leeuwin Current system.  

E-Print Network [OSTI]

??[Truncated abstract] The study of eastern ocean boundary currents has been principally restricted to the Pacific and Atlantic ocean regions. The traditional view of the… (more)

Meuleners, Michael Joseph

2005-01-01T23:59:59.000Z

264

Sensitivity of mesoscale gravity waves to the baroclinicity of jet-front systems  

E-Print Network [OSTI]

energy for five experiments. Stars indicate the timing for each case in Fig. 20. Big circles indicate the timing in Fig. 15. ............................................................................................ 37 xi FIGURE... of mean momentum, energy and potential vorticity allowing the flow to regain a geostrophically balanced state (Cahn 1945; Blumen 1972; Kaplan et al. 1997). In addition, earlier case studies with observational data also revealed a significant impact...

Wang, Shuguang

2006-04-12T23:59:59.000Z

265

Patterns of Convection in the Tropical Western Pacific  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Patterns of Convection in the Tropical Western Pacific Patterns of Convection in the Tropical Western Pacific J. H. Mather Pacific Northwest National Laboratory Richland, Washington Introduction Convection is ubiquitous throughout the maritime continent region. However, the frequency of convec- tion is not uniform. While much of this region does not experience seasons to the same degree as one finds in mid-latitudes, the annual cycle of the sun's passage does have a large impact on convection throughout the maritime continent and the tropical western Pacific. The distribution of islands also affects convection in a variety of ways. Atmospheric Radiation Measurement (ARM) Program has three sites in the Tropical Western Pacific (TWP) region, illustrated in Figure 1. The sites are located on Manus, Nauru, and at Darwin, Australia.

266

ARM - Field Campaign - Year of Tropical Convection (YOTC)  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

govCampaignsYear of Tropical Convection (YOTC) govCampaignsYear of Tropical Convection (YOTC) Campaign Links Year of Tropical Convection Website Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Campaign : Year of Tropical Convection (YOTC) 2008.05.01 - 2010.04.30 Lead Scientist : Sally McFarlane Description Example of a sonde profile available from the ARM Archive The realistic representation of tropical convection in global atmospheric models is a long-standing challenge for weather and global climate models. The lack of fundamental knowledge in this area causes difficulties in modeling and predicting prominent phenomena of the tropical atmosphere such as the inter-tropical convergence zone (ITCZ), El-Nino/Southern Oscillation (ENSO), monsoons, the Madden-Julian Oscillation (MJO), tropical cyclones,

267

Limiting Factors for Convective Cloud Top Height in the Tropics  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Limiting Factors for Convective Cloud Top Limiting Factors for Convective Cloud Top Height in the Tropics M. P. Jensen and A. D. Del Genio National Aeronautics and Space Administration Goddard Institute for Space Studies Columbia University New York, New York Introduction Populations of tropical convective clouds are mainly comprised of three types: shallow trade cumulus, mid-level cumulus congestus and deep convective clouds (Johnson et al. 1999). Each of these cloud types has different impacts on the local radiation and water budgets. For climate model applications it is therefore important to understand the factors which determine the type of convective cloud that will occur. In this study, we concentrate on describing the factors that limit the cloud-top heights of mid-

268

Utilizing CLASIC observations and multiscale models to study the impact of improved Land surface representation on modeling cloud- convection  

SciTech Connect (OSTI)

The CLASIC experiment was conducted over the US southern great plains (SGP) in June 2007 with an objective to lead an enhanced understanding of the cumulus convection particularly as it relates to land surface conditions. This project was design to help assist with understanding the overall improvement of land atmosphere convection initiation representation of which is important for global and regional models. The study helped address one of the critical documented deficiency in the models central to the ARM objectives for cumulus convection initiation and particularly under summer time conditions. This project was guided by the scientific question building on the CLASIC theme questions: What is the effect of improved land surface representation on the ability of coupled models to simulate cumulus and convection initiation? The focus was on the US Southern Great Plains region. Since the CLASIC period was anomalously wet the strategy has been to use other periods and domains to develop the comparative assessment for the CLASIC data period, and to understand the mechanisms of the anomalous wet conditions on the tropical systems and convection over land. The data periods include the IHOP 2002 field experiment that was over roughly same domain as the CLASIC in the SGP, and some of the DOE funded Ameriflux datasets.

Niyogi, Devdutta S. [Purdue

2013-06-07T23:59:59.000Z

269

LOW MACH NUMBER MODELING OF CONVECTION IN HELIUM SHELLS ON SUB-CHANDRASEKHAR WHITE DWARFS. I. METHODOLOGY  

SciTech Connect (OSTI)

We assess the robustness of a low Mach number hydrodynamics algorithm for modeling helium shell convection on the surface of a white dwarf in the context of the sub-Chandrasekhar model for Type Ia supernovae. We use the low Mach number stellar hydrodynamics code, MAESTRO, to perform three-dimensional, spatially adaptive simulations of convection leading up to the point of the ignition of a burning front. We show that the low Mach number hydrodynamics model provides a robust description of the system.

Zingale, M.; Orvedahl, R. J. [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800 (United States)] [Department of Physics and Astronomy, Stony Brook University, Stony Brook, NY 11794-3800 (United States); Nonaka, A.; Almgren, A. S.; Bell, J. B. [Center for Computational Sciences and Engineering, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States)] [Center for Computational Sciences and Engineering, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 (United States); Malone, C. M. [Department of Astronomy and Astrophysics, The University of California, Santa Cruz, Santa Cruz, CA 95064 (United States)] [Department of Astronomy and Astrophysics, The University of California, Santa Cruz, Santa Cruz, CA 95064 (United States)

2013-02-10T23:59:59.000Z

270

Impact of mesoscale eddies on water transport between the Pacific Ocean and the Bering Sea  

E-Print Network [OSTI]

Sea surface height anomalies observed by satellites in 1993--2012 are combined with simulation and observations by surface drifters and Argo floats to study water flow pattern in the Near Strait (NS) connected the Pacific Ocean with the Bering Sea. Daily Lagrangian latitudinal maps, computed with the AVISO surface velocity field, and calculation of the transport across the strait show that the flow through the NS is highly variable and controlled by mesoscale and submesoscale eddies in the area. On the seasonal scale, the flux through the western part of the NR is negatively correlated with the flux through its eastern part ($r=-0.93$). On the interannual time scale, a significant positive correlation ($r=0.72$) is diagnosed between the NS transport and the wind stress in winter. Increased southward component of the wind stress decreases the northward water transport through the strait. Positive wind stress curl over the strait area in winter--spring generates the cyclonic circulation and thereby enhances the...

Prants, S V; Budyansky, M V; Uleysky, M Yu

2013-01-01T23:59:59.000Z

271

Lattice Boltzmann method for double-diffusive natural convection  

Science Journals Connector (OSTI)

A lattice Boltzmann method for double-diffusive natural convection is presented. The model combines a multicomponent lattice Boltzmann scheme with a finite-difference solution of the energy equation to simulate natural convection caused by gradients in temperature and concentration. The model is validated both in two and three dimensions, and the agreement with literature data is satisfactory. A case study of thermosolutal convection of air in a cubical enclosure with horizontal thermal and solutal gradients is presented, exhibiting a rich variety of flow structures.

F. Verhaeghe; B. Blanpain; P. Wollants

2007-04-12T23:59:59.000Z

272

Numerical and Experimental Modeling of Natural Convection for a Cryogenic Prototype of a Titan  

E-Print Network [OSTI]

in Sutherland's law D = diameter g = gravitation acceleration h = convection coefficient k = thermal

Colonius, Tim

273

Convective heat transfer characteristics of China RP-3 aviation kerosene at supercritical pressure  

E-Print Network [OSTI]

Convective heat transfer characteristics of China RP-3 aviation kerosene at supercritical pressure Keywords: Supercritical pressure Aviation kerosene Convective heat transfer Numerical study a b s t r a c convective in kerosene pipe flow is complicated. Here the convective heat transfer characteristics of China

Guo, Zhixiong "James"

274

Penetration of Convective Envelope into Stellar Core and Existence of Neutrino Loss  

Science Journals Connector (OSTI)

......the products of Penetration of Convective Envelope...convective mixing for any rate of the neutrino...superadiabaticity is determined Penetration of Convective Envelope...used.15> 459 the rate of Since the main...energy generation rate is sensitive to...smaller mass stars, penetration of convective envelope......

Ken'ichi Nomoto

1974-08-01T23:59:59.000Z

275

Simulating Flash Flood Events: Importance of the Subgrid Representation of Convection  

Science Journals Connector (OSTI)

The Pennsylvania State University–NCAR Mesoscale Model is used to simulate six flash flood events that occurred in the central and eastern United States. Results suggest that standard model simulations of 24-h accumulated precipitation provide ...

Phillip L. Spencer; David J. Stensrud

1998-11-01T23:59:59.000Z

276

Ensemble Sensitivity Analysis Applied to a Southern Plains Convective Event  

Science Journals Connector (OSTI)

Forecast sensitivity of an April 2012 severe convection event in northern Texas is investigated with a high resolution Weather Research and Forecasting (WRF) model-based Ensemble Kalman Filter (EnKF). Through Ensemble Sensitivity Analysis (ESA), ...

Christopher N. Bednarczyk; Brian C. Ancell

277

Theory for induced convection experiments in the tokamak edge  

E-Print Network [OSTI]

Theory for induced convection experiments in the tokamak edge P. Helander1 , D.D. Ryutov2 , and R National Laboratory, Livermore, USA By biasing alternate divertor plates in a tokamak, one can create

278

Observation of moisture tendencies related to shallow convection  

Science Journals Connector (OSTI)

Tropospheric moisture is a key factor controlling the global climate and its variability. For instance, moistening of the lower troposphere is necessary to trigger the convective phase of a Madden-Julian Oscillation. However, the relative ...

H. Bellenger; K. Yoneyama; M. Katsumata; T. Nishizawa; K. Yasunaga; R. Shirooka

279

Initiating Moist Convection in an Inhomogeneous Layer by Uniform Ascent  

Science Journals Connector (OSTI)

Using aircraft data from the recent Dominica Experiment (DOMEX) project in Dominica, the authors evaluate a modified version of Woodcock’s theory of moist convective initiation. Upstream of Dominica, anticorrelated fluctuations in temperature and ...

Alison D. Nugent; Ronald B. Smith

2014-12-01T23:59:59.000Z

280

Effects of aerosols on deep convective cumulus clouds  

E-Print Network [OSTI]

This work investigates the effects of anthropogenic aerosols on deep convective clouds and the associated radiative forcing in the Houston area. The Goddard Cumulus Ensemble model (GCE) coupled with a spectral-bin microphysics is employed...

Fan, Jiwen

2009-05-15T23:59:59.000Z

Note: This page contains sample records for the topic "mesoscale convective systems" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

Evaluation of Trigger Functions for Convective Parameterization Schemes Using Observations  

Science Journals Connector (OSTI)

Realistic simulation of different modes of atmospheric variability ranging from diurnal cycle to interannual variation in global climate models (GCMs) depends crucially on the convection trigger criteria. In this study, using the data from ...

E. Suhas; Guang J. Zhang

2014-10-01T23:59:59.000Z

282

Scaling Laws for the Heterogeneously Heated Free Convective Boundary Layer  

Science Journals Connector (OSTI)

The heterogeneously heated free convective boundary layer (CBL) is investigated by means of dimensional analysis and results from large-eddy simulations (LES) and direct numerical simulations (DNS). The investigated physical model is a CBL that ...

Chiel C. van Heerwaarden; Juan Pedro Mellado; Alberto De Lozar

2014-11-01T23:59:59.000Z

283

A Unified Convection Scheme (UNICON). Part I: Formulation  

Science Journals Connector (OSTI)

The author develops a unified convection scheme (UNICON) that parameterizes relative (i.e., with respect to the grid-mean vertical flow) subgrid vertical transport by nonlocal asymmetric turbulent eddies. UNICON is a process-based model of subgrid ...

Sungsu Park

2014-11-01T23:59:59.000Z

284

Convective stability of carbon sequestration in anisotropic porous media  

Science Journals Connector (OSTI)

...Convective stability of carbon sequestration in anisotropic porous media...media|stability theory|carbon sequestration| 1. Introduction The world's...processes occurring during carbon dioxide sequestration in underground saline aquifers...

2014-01-01T23:59:59.000Z

285

Land-atmosphere interaction and radiative-convective equilibrium  

E-Print Network [OSTI]

I present work on several topics related to land-atmosphere interaction and radiative-convective equilibrium: the first two research chapters invoke ideas related to land-atmosphere interaction to better understand ...

Cronin, Timothy (Timothy Wallace)

2014-01-01T23:59:59.000Z

286

Physical Characterization of Tropical Oceanic Convection Observed in KWAJEX  

Science Journals Connector (OSTI)

The Tropical Rainfall Measuring Mission (TRMM) Kwajalein Experiment (KWAJEX) was designed to obtain an empirical physical characterization of precipitating convective clouds over the tropical ocean. Coordinated datasets were collected by three ...

Sandra E. Yuter; Robert A. Houze Jr.; Eric A. Smith; Thomas T. Wilheit; Edward Zipser

2005-04-01T23:59:59.000Z

287

A Unified Convection Scheme (UNICON). Part II: Simulation  

Science Journals Connector (OSTI)

A unified convection scheme (UNICON) is implemented into the Community Atmosphere Model, version 5 (CAM5), and tested in single-column and global simulations forced by observed sea surface temperature. Compared to CAM5, UNICON substantially ...

Sungsu Park

2014-11-01T23:59:59.000Z

288

Interaction between surface and atmosphere in a convective boundary layer /  

E-Print Network [OSTI]

heat, and thermal conductivity of the ground and grid sizegrid was stretched uniformly to 0.1 m resolution. The heatheat flux) are friction velocity and convective velocity respectively. The grid

Garai, Anirban

2013-01-01T23:59:59.000Z

289

Mesoscale Simulations of a Wind Ramping Event for Wind Energy Prediction  

SciTech Connect (OSTI)

Ramping events, or rapid changes of wind speed and wind direction over a short period of time, present challenges to power grid operators in regions with significant penetrations of wind energy in the power grid portfolio. Improved predictions of wind power availability require adequate predictions of the timing of ramping events. For the ramping event investigated here, the Weather Research and Forecasting (WRF) model was run at three horizontal resolutions in 'mesoscale' mode: 8100m, 2700m, and 900m. Two Planetary Boundary Layer (PBL) schemes, the Yonsei University (YSU) and Mellor-Yamada-Janjic (MYJ) schemes, were run at each resolution as well. Simulations were not 'tuned' with nuanced choices of vertical resolution or tuning parameters so that these simulations may be considered 'out-of-the-box' tests of a numerical weather prediction code. Simulations are compared with sodar observations during a wind ramping event at a 'West Coast North America' wind farm. Despite differences in the boundary-layer schemes, no significant differences were observed in the abilities of the schemes to capture the timing of the ramping event. As collaborators have identified, the boundary conditions of these simulations probably dominate the physics of the simulations. They suggest that future investigations into characterization of ramping events employ ensembles of simulations, and that the ensembles include variations of boundary conditions. Furthermore, the failure of these simulations to capture not only the timing of the ramping event but the shape of the wind profile during the ramping event (regardless of its timing) indicates that the set-up and execution of such simulations for wind power forecasting requires skill and tuning of the simulations for a specific site.

Rhodes, M; Lundquist, J K

2011-09-21T23:59:59.000Z

290

The Convective Instability Pathway to Warm Season Drought in Texas. Part I: The Role of Convective Inhibition and Its Modulation by Soil Moisture  

Science Journals Connector (OSTI)

This research is designed to investigate how convective instability influences monthly mean precipitation in Texas in the summertime and to examine the modulation of convective instability and precipitation by local and regional forcings. Since ...

Boksoon Myoung; John W. Nielsen-Gammon

2010-09-01T23:59:59.000Z

291

Natural Convection Heat Transfer in a Rectangular Liquid Metal Pool With Bottom Heating and Top Cooling  

SciTech Connect (OSTI)

An experimental study is performed to investigate the natural convection heat transfer characteristics with subcooled coolant to create engineering database for basic applications in a lead alloy cooled reactor. Tests are performed in the ALTOS (Applied Liquid-metal Thermal Operation Study) apparatus as part of MITHOS (Metal Integrated Thermo Hydrodynamic Operation System). A relationship is determined between the Nusselt number Nu and the Rayleigh number Ra in the liquid metal rectangular pool. Results are compared with correlations and experimental data in the literature. Given the similar Ra condition, the present test results for Nu of the liquid metal pool with top subcooling are found to be similar to those predicted by the existing correlations or experiments. The current test results are utilized to develop natural convection heat transfer correlations applicable to low Prandtl number Pr fluids that are heated from below and cooled by the external coolant above. Results from this study are slated to be used in designing BORIS (Battery Optimized Reactor Integral System), a small lead cooled modular fast reactor for deployment at remote sites cycled with MOBIS (Modular Optimized Brayton Integral System) for electricity generation, tied with NAVIS (Naval Application Vessel Integral System) for ship propulsion, joined with THAIS (Thermochemical Hydrogen Acquisition Integral System) for hydrogen production, and coupled with DORIS (Desalination Optimized Reactor Integral System) for seawater desalination. Tests are performed with Wood's metal (Pb-Bi-Sn-Cd) filling a rectangular pool whose lower surface is heated and upper surface cooled by forced convection of water. The test section is 20 cm long, 11.3 cm high and 15 cm wide. The simulant has a melting temperature of 78 deg. C. The constant temperature and heat flux condition was realized for the bottom heating once the steady state had been met. The test parameters include the heated bottom surface temperature of the liquid metal pool, the input power to the bottom surface of the section, and the coolant temperature. (authors)

Lee, Il S.; Yu, Yong H.; Son, Hyoung M.; Hwang, Jin S.; Suh, Kune Y. [Seoul National University, 599 Gwanangno, Gwanak-gu, Seoul, 151-742 (Korea, Republic of)

2006-07-01T23:59:59.000Z

292

Simulation of Rayleigh-Benard convection using a lattice Boltzmann method  

SciTech Connect (OSTI)

Rayleigh-Benard convection is numerically simulated in two and three dimensions using a recently developed two-component lattice Boltzmann equation (LBE) method. The density field of the second component, which evolves according to the advection-diffusion equation of a passive scalar, is used to simulate the temperature field. A body force proportional to the temperature is applied, and the system satisfies the Boussinesq equation except for a slight compressibility. A no-slip, isothermal boundary condition is imposed in the vertical direction, and periodic boundary conditions are used in horizontal directions. The critical Rayleigh number for the onset of the Rayleigh-Benard convection agrees with the theoretical prediction. As the Rayleigh number is increased higher, the steady two-dimensional convection rolls become unstable. The wavy instability and aperiodic motion observed, as well as the Nusselt number as a function of the Rayleigh number, are in good agreement with experimental observations and theoretical predictions. The LBE model is found to be efficient, accurate, and numerically stable for the simulation of fluid flows with heat and mass transfer. {copyright} {ital 1997} {ital The American Physical Society}

Shan, X. [U.S. Air Force Phillips Laboratory, Hanscom Air Force Base, Massachusetts 01731 (United States)] [U.S. Air Force Phillips Laboratory, Hanscom Air Force Base, Massachusetts 01731 (United States); [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

1997-03-01T23:59:59.000Z

293

Does the ECMWF IFS convection parameterisation with stochastic physics correctly reproduce relationships between convection and the large-scale state?  

Science Journals Connector (OSTI)

Important questions concerning parameterisation of tropical convection are how should sub-grid scale variability be represented, and which large-scale variables should be used in the parameterisations? Here we compare the statistics of ...

Peter A. G. Watson; H. M. Christensen; T. N. Palmer

294

Compactification of Patterns by a Singular Convection or Stress  

SciTech Connect (OSTI)

A wide variety of propagating disturbances in physical systems are described by equations whose solutions lack a sharp propagating front. We demonstrate that presence of particular nonlinearities may induce such fronts. To exemplify this idea, we study both dissipative u{sub t}+{partial_derivative}{sub x}f(u)=u{sub xx} and dispersive u{sub t}+{partial_derivative}{sub x}f(u)+u{sub xxx}=0 patterns, and show that a weakly singular convection f(u)=-u{sup {alpha}}+u{sup m}, 0<{alpha}<1

Rosenau, Philip [School of Mathematical Sciences, Tel Aviv University, Tel Aviv 69978 (Israel)

2007-12-07T23:59:59.000Z

295

Layer inflow into precipitating convection over the western tropical Pacific  

E-Print Network [OSTI]

and the relativecoarseness of the TOGA COARE soundings.The available input data from the mesoscale model consist of three wind components(u, v and w), temperature, pressure, water vapour, rain water, cloud water and cloudice. The last two quantities, by de? nition, have zero... by linear interpolation of the hourly supplied MM5 data, to the right-hand side of the u, v, w, temperature, pressure and water vapour equations in a narrowzone near the lateral boundaries. The forcing is strongest at the boundary and decreasesto a ? fth...

Mechem, David B.; Houze, Robert A. Jr.; Chen, Shuyi S.

2002-07-01T23:59:59.000Z

296

CGL Defect Chaos and Bursts in Hexagonal Rotating non-Boussinesq Convection  

E-Print Network [OSTI]

We employ numerical computations of the full Navier-Stokes equations to investigate non-Boussinesq convection in a rotating system using water as a working fluid. We identify two regimes. For weak non-Boussinesq effects the Hopf bifurcation from steady to oscillating (whirling) hexagons is supercritical and typical states exhibit defect chaos that is systematically described by the cubic complex Ginzburg-Landau equation. For stronger non-Boussinesq effects the Hopf bifurcation becomes subcritical and the oscillations exhibit localized chaotic bursting, which can be modeled by a quintic complex Ginzburg-Landau equation.

Santiago Madruga; Hermann Riecke; Werner Pesch

2005-07-26T23:59:59.000Z

297

Convective exergy losses of developing slip flow in microchannels  

Science Journals Connector (OSTI)

A numerical formulation of convective exergy losses in microchannels is developed. Using a new convection model (called Non-Inverted Skew Upwind Scheme (NISUS)), the predicted velocity field is post-processed to determine frictional irreversibilities within the microchannel. Boundary conditions are established from a first-order slip velocity, based on streamwise temperature gradients and transverse velocity gradients at the wall. Parametric studies are conducted for varying flow rates, channel aspect ratios, slip coefficients and pressure ratios across the microchannel. The predicted exergy destruction results provide useful new data, from which design modifications can be made to reduce power input when transporting fluid through a microchannel.

E.O.B. Ogedengbe; G.F. Naterer; M.A. Rosen

2007-01-01T23:59:59.000Z

298

Spiral-pattern formation in Rayleigh-Benard convection  

SciTech Connect (OSTI)

We present a numerical study of the spontaneous formation of spiral patterns in Rayleigh-Benard convection in non-Boussinesq fluids. We solve a generalized two-dimensional Swift-Hohenberg equation that includes a quadratic nonlinearity and coupling to mean flow. We show that this model predicts in quantitative detail many of the features observed experimentally in studies of Rayleigh-Benard convection in CO[sub 2] gas. In particular, we study the appearance and stability of a rotating spiral state obtained during the transition from an ordered hexagonal state to a roll state.

Xi, H.; Gunton, J.D. (Department of Physics, Lehigh University, Bethlehem, Pennsylvania 18015 (United States)); Vinals, J. (Supercomputer Computations Research Institute, B-186, and Department of Chemical Engineering, B-203, Florida State University, Tallahassee, Florida 32306-4052 (United States))

1993-05-01T23:59:59.000Z

299

The Three-Dimensional Morphology of Simulated and Observed Convective Storms over Southern England  

Science Journals Connector (OSTI)

A set of high-resolution radar observations of convective storms has been collected to evaluate such storms in the Met Office Unified Model during the Dynamical and Microphysical Evolution of Convective Storms (DYMECS) project. The 3-GHz ...

Thorwald H. M. Stein; Robin J. Hogan; Kirsty E. Hanley; John C. Nicol; Humphrey W. Lean; Robert S. Plant; Peter A. Clark; Carol E. Halliwell

2014-09-01T23:59:59.000Z

300

Lateral Heat Exchange after the Labrador Sea Deep Convection in 2008  

Science Journals Connector (OSTI)

The mechanisms through which convected water restratifies in the Labrador Sea are still under debate. The Labrador Sea restratification after deep convection in the 2007/08 winter is studied with an eddy-resolving numerical model. The modeled ...

Weiwei Zhang; Xiao-Hai Yan

2014-12-01T23:59:59.000Z

Note: This page contains sample records for the topic "mesoscale convective systems" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

Convective heat transfer in the nonstationary motion of a Maxwellian fluid between parallel planes  

Science Journals Connector (OSTI)

The convective heat-transfer problem is investigated for a Maxwellian fluid in generalized Couette flow in the case...

Z. P. Shul'man; É. A. Zal'tsgendler

1970-06-01T23:59:59.000Z

302

Controllable Organization of Quantum Dots into Mesoscale Wires and Cables via Interfacial Block Copolymer Self-Assembly  

Science Journals Connector (OSTI)

Controllable Organization of Quantum Dots into Mesoscale Wires and Cables via Interfacial Block Copolymer Self-Assembly ... Figure 2b,c shows higher magnification AFM images of interesting features within the branched cable network, including a typical branch point (b) and a QD/polymer ring incorporated into the cable (c). ... It was noted that several of the LB films containing ring/cable structures also contained small planar aggregates along the length of the cables where an elevated rim was present at the edge of a relatively flat surface, similar to a continent as described by Devereaux et al.26 It appears that these flat surfaces tend to rupture by formation of a single central hole in a secondary dewetting process, followed by the radial growth of the hole. ...

Robert B. Cheyne; Matthew G. Moffitt

2007-02-23T23:59:59.000Z

303

North Australian Cloud Lines  

Science Journals Connector (OSTI)

A satellite classification and climatology of propagating mesoscale cloud fines in northern Australia is presented. These cloud fines range from long, narrow lines of shallow convection to extensive deep convective squall lines with mesoscale ...

W. Drosdowsky; G. J. Holland

1987-11-01T23:59:59.000Z

304

Boussinesq convection and motions of boundary spheres in a rotating spherical shell  

E-Print Network [OSTI]

RIMS­1772 Boussinesq convection and motions of boundary spheres in a rotating spherical shell #12; Boussinesq convection and motions of boundary spheres in a rotating spherical shell Keiji Kimura; Abstract Boussinesq thermal convection in rotating spheres or spherical shells has been investigated

305

Boussinesq convection and motions of boundary spheres in a rotating spherical shell  

E-Print Network [OSTI]

RIMS-1772 Boussinesq convection and motions of boundary spheres in a rotating spherical shell #12;Boussinesq convection and motions of boundary spheres in a rotating spherical shell Keiji Kimura Boussinesq thermal convection in rotating spheres or spherical shells has been investigated for over half

306

Evolution du contenu physique 1. Nouveau bloc couche limite convection nuages (nouvelle physique)  

E-Print Network [OSTI]

Evolution du contenu physique 1. Nouveau bloc couche limite ­ convection ­ nuages (nouvelle physique) ON DISPOSE D'UN NOUVEAU CADRE DE TRAVAIL. ?? - Convection /relief (Jean-Yves Grandpeix, Jingmei Yu, Alain Lahelec) ++ - glace dans la convection (Arnaud Jam, Jean-Yves Grandpeix) ?? - Modèle micro-physique

Madeleine, Jean-Baptiste

307

Review of fluid flow and convective heat transfer within rotating disk cavities  

E-Print Network [OSTI]

Review of fluid flow and convective heat transfer within rotating disk cavities with impinging jet * Corresponding author : souad.harmand@univ-valenciennes.fr Abstract Fluid flow and convective heat transfer, are treated in details in this review. The review focuses on convective heat transfer in predominantly outward

Boyer, Edmond

308

A numerical study of convection with an ambient wind field  

E-Print Network [OSTI]

. The citations on the following pages follow the style of the Journal of the Atmos heric Sciences. Orville (1968) constructed a convective model based on the same equations as those used by Assi. He concerned himself with the development of cumulus clouds over...

Cottrell, Kit Garfield

1970-01-01T23:59:59.000Z

309

Constraints on mantle convection from seismic tomography and flow modeling  

E-Print Network [OSTI]

In this thesis I combine high resolution seismic tomography and realistic flow modeling to constrain mantle convection. The bulk of the data used in the tomographic imaging are millions of P, pP and pwP travel time residuals, ...

Kárason, Hrafnkell, 1970-

2002-01-01T23:59:59.000Z

310

The Influence of Wind Speed on Shallow Marine Cumulus Convection  

Science Journals Connector (OSTI)

The role of wind speed on shallow marine cumulus convection is explored using large-eddy simulations and concepts from bulk theory. Focusing on cases characteristic of the trades, the equilibrium trade wind layer is found to be deeper at stronger ...

Louise Nuijens; Bjorn Stevens

2012-01-01T23:59:59.000Z

311

Q.J. R. Meteorol. SOC.(1997),123, pp. 1771-1778 Comments on `On large-scale circulations in convecting atmospheres' by  

E-Print Network [OSTI]

overview of the dynamics of convecting systems and their interaction with larger-scale cir- culations. As such it prompted us to organize a semester-long seminar devoted to the study of these interactions, and to ENB fluxes in generating instability, and go so far as to call it `an influential and lengthy dead-end road

Randall, David A.

312

A Test of the Simulation of Tropical Convective Cloudiness by a Cloud-Resolving Model MARIO A. LOPEZ, DENNIS L. HARTMANN, PETER N. BLOSSEY, ROBERT WOOD,  

E-Print Network [OSTI]

un- certainties in projections of future climates (Bony et al. 2006; Solomon et al. 2007). Clouds solar radiation, although their effect on the net energy balance is often much less than with intense tropical convective systems are known to have long lifetimes and to cover large areas, accounting

Hartmann, Dennis

313

Research Highlight  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Global Variability of Mesoscale Convective System Anvil Structure from Global Variability of Mesoscale Convective System Anvil Structure from A-train Satellite Data Submitter: Yuan, J., University of Washington Houze, R., University of Washington Area of Research: Cloud Distributions/Characterizations Working Group(s): Cloud Properties Journal Reference: Yuan J and RA Houze. 2010. "Global variability of mesoscale convective system anvil structure from A-train satellite data." Journal of Climate, 23, 5864-5888. Figure. 1 Annual mean (2007) climatology of anvil clouds associated with (a) small separated MCSs (<12000 km^2, the smallest 25%), (b) large separated MCSs (>40000 km^2, the largest 25%), and (c) connected MCSs. The color indicates percentage of area covered by MCS anvil clouds for each 5°x5° grid. In the tropics, upper-level clouds containing ice and mixtures of ice and

314

A Comparison of Precipitation Forecast Skill between Small Convection-Allowing and Large Convection-Parameterizing Ensembles  

E-Print Network [OSTI]

Submitted to Weather and Forecasting in October 2008, Accepted in January 2009 * Corresponding author) Weather Research and Forecasting (WRF) model ensemble, which cover a similar domain over the central-convection resolution (PCR) ensembles. Computation of various precipitation skill metrics for probabilistic

Droegemeier, Kelvin K.

315

Modeling the Dynamical Coupling of Solar Convection with the Radiative Interior  

Science Journals Connector (OSTI)

The global dynamics of a rotating star like the Sun involves the coupling of a highly turbulent convective envelope overlying a seemingly benign radiative interior. We use the anelastic spherical harmonic code to develop a new class of three-dimensional models that nonlinearly couple the convective envelope to a deep stable radiative interior. The numerical simulation assumes a realistic solar stratification from r = 0.07 up to 0.97R (with R the solar radius), thus encompassing part of the nuclear core up through most of the convection zone. We find that a tachocline naturally establishes itself between the differentially rotating convective envelope and the solid body rotation of the interior, with a slow spreading that is here diffusively controlled. The rapid angular momentum redistribution in the convective envelope leads to a fast equator and slow poles, with a conical differential rotation achieved at mid-latitudes, much as has been deduced by helioseismology. The convective motions are able to overshoot downward about 0.04R into the radiative interior. However, the convective meridional circulation there is confined to a smaller penetration depth and is directed mostly equatorward at the base of the convection zone. Thermal wind balance is established in the lower convection zone and tachocline but departures are evident in the upper convection zone. Internal gravity waves are excited by the convective overshooting, yielding a complex wave field throughout the radiative interior.

Allan Sacha Brun; Mark S. Miesch; Juri Toomre

2011-01-01T23:59:59.000Z

316

Scaling Laws for Convection with Temperature-dependent Viscosity and Grain-damage  

E-Print Network [OSTI]

Numerical experiments of convection with grain-damage are used to develop scaling laws for convective heat flow, mantle velocity, and plate velocity across the stagnant lid and plate-tectonic regimes. Three main cases are presented in order of increasing complexity: a simple case wherein viscosity is only dependent on grainsize, a case where viscosity depends on temperature and grainsize, and finally a case where viscosity is temperature and grainsize sensitive, and the grain-growth (or healing) is also temperature sensitive. In all cases, convection with grain-damage scales differently than Newtonian convection due to the effects of grain-damage. For the fully realistic case, numerical results show stagnant lid convection, fully mobilized convection that resembles the temperature-independent viscosity case, and partially mobile or transitional convection, depending on damage to healing ratio, Rayleigh number, and the activation energies for viscosity and healing. Applying our scaling laws for the fully reali...

Foley, Bradford J

2014-01-01T23:59:59.000Z

317

Spatio-temporal analysis of Rayleigh-B{acute e}nard convection  

SciTech Connect (OSTI)

The analysis of Rayleigh-B{acute e}nard convection in a thin layer of an incompressible fluid caused by heating from below, is based on the Navier-Stokes equations. In planar geometry the Navier-Stokes equations in Bousinesq-approximation reduce to two nonlinear coupled partial differential equations for the velocity flux function {xi} and the temperature deviation {theta}. These equations are analyzed in form of spatial Fourier modes with time-dependent amplitudes. Only modes corresponding to free-free boundary conditions were selected. In this way, a set of ten coupled nonlinear ordinary differential equations for the mode amplitudes was obtained. These equations were solved numerically for different Rayleigh numbers. The temporal information in the ten dimensional phase space of the mode amplitudes is analyzed with respect to the dimension of the attractor. In addition, a time series of flow patterns in real space is constructed. For this spatio-temporal patterns the empirical orthonormal functions are determined and used to find the temporal evolution from the projection onto the basic vectors. Finally the result of different types of analysis were compared. This should lead to a better understanding how to analyze real systems in terms of observational data, e.g., thermal convection on the surface of the sun. {copyright} {ital 1996 American Institute of Physics.}

Lainscsek, C.S.; Schuerrer, F. [Institut fuer Theoretische Physik, Technische Universitaet Graz, Petersgasse 16, A-8010 Graz, Oesterreich (Austria)

1996-06-01T23:59:59.000Z

318

Inertial and Aerodynamic Tail Steering of a Meso-scale Legged Robot  

E-Print Network [OSTI]

a constant yaw disturbance to a robotic system, but this mayYaw data for the tail and body were recorded using an OptiTrack 1 motion capture system.

Kohut, Nicholas Jospeh

2013-01-01T23:59:59.000Z

319

ARM - Field Campaign - Midlatitude Continental Convective Clouds Experiment  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Experiment Experiment (MC3E): Multi-Frequency Profilers Related Campaigns Midlatitude Continental Convective Clouds Experiment (MC3E) 2011.04.22, Jensen, SGP Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send Campaign : Midlatitude Continental Convective Clouds Experiment (MC3E): Multi-Frequency Profilers 2011.04.22 - 2011.06.06 Lead Scientist : Christopher Williams For data sets, see below. Description The scientific focus was to study the vertical structure of precipitation in a vertical column over the SGP Central Facility. These multi-frequency profiler observations enabled directly measuring the vertical air motion and retrieving the raindrop size distributions from near the surface to just under the freezing level. These profilers were deployed during MC3E

320

ARM - Field Campaign - COPS - Initiation of Convection and the  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

govCampaignsCOPS - Initiation of Convection and the Microphysical govCampaignsCOPS - Initiation of Convection and the Microphysical Properties of Clouds in Orographic Terrain Campaign Links AMF Black Forest Deployment Related Campaigns COPS - AOS Intercomparison 2007.08.09, Jefferson, AMF COPS - ADMIRARI at Black Forest 2007.07.30, Battaglia, AMF COPS - University of Cologne Micromet Station 2007.07.23, Schween, AMF COPS - Cloud Microwave Validation Experiment in Support of CLOWD 2007.06.22, Vogelmann, AMF COPS - WILI Coherent Doppler Wind Lidar at Black Forest 2007.05.10, Althausen, AMF COPS - Multi Wavelength Raman Lidar (MWL) at Black Forest 2007.05.10, Althausen, AMF COPS - 35.5 GHz Cloud Radar Comparison at Black Forest 2007.05.01, Handwerker, AMF COPS - HATPRO at Black Forest 2007.04.01, Crewell, AMF COPS - Micro-Rain Radar at Black Forest

Note: This page contains sample records for the topic "mesoscale convective systems" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

Bifurcation analysis of interacting stationary modes in thermohaline convection  

SciTech Connect (OSTI)

The Boussinesq equations for thermohaline convection in a finite two-dimensional box and with stress-free boundaries are considered. There are critical values of the aspect ratio at which the conduction state becomes unstable to two different roll patterns simultaneously. Near such a critical value a center manifold reduction allows us to reduce the dynamical behavior of the Boussinesq equations to a standard normal form equation that describes the interaction of two stationary modes. We present explicit analytical expressions for the linear and nonlinear coefficients on which the normal form depends. A numerical investigation of these coefficients leads to a division of the space of parameters (Prandtl number, solute Rayleigh number, Lewis number) into various regions that give rise to qualitatively different bifurcation behavior. Besides those encountered in ordinary convection, a variety of further phenomena is found, in particular in a vicinity of double tricritical points.

Neveling, M.; Dangelmayr, G.

1988-09-01T23:59:59.000Z

322

Turbulent equipartitions in two dimensional drift convection  

SciTech Connect (OSTI)

Unlike the thermodynamic equipartition of energy in conservative systems, turbulent equipartitions (TEP) describe strongly non-equilibrium systems such as turbulent plasmas. In turbulent systems, energy is no longer a good invariant, but one can utilize the conservation of other quantities, such as adiabatic invariants, frozen-in magnetic flux, entropy, or combination thereof, in order to derive new, turbulent quasi-equilibria. These TEP equilibria assume various forms, but in general they sustain spatially inhomogeneous distributions of the usual thermodynamic quantities such as density or temperature. This mechanism explains the effects of particle and energy pinch in tokamaks. The analysis of the relaxed states caused by turbulent mixing is based on the existence of Lagrangian invariants (quantities constant along fluid-particle or other orbits). A turbulent equipartition corresponds to the spatially uniform distribution of relevant Lagrangian invariants. The existence of such turbulent equilibria is demonstrated in the simple model of two dimensional electrostatically turbulent plasma in an inhomogeneous magnetic field. The turbulence is prescribed, and the turbulent transport is assumed to be much stronger than the classical collisional transport. The simplicity of the model makes it possible to derive the equations describing the relaxation to the TEP state in several limits.

Isichenko, M.B.; Yankov, V.V. [Univ. of California, Santa Barbara, CA (United States). Inst. for Theoretical Physics

1995-07-25T23:59:59.000Z

323

The CHUVA Project how does convection vary across the Brazil?  

E-Print Network [OSTI]

1 The CHUVA Project ­ how does convection vary across the Brazil? Luiz A. T. Machado1 , Maria A. F de Previsão de Tempo e Estudos Climáticos (CPTEC), Brazil. 2. Universidade de São Paulo. Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Brazil. 3. Departamento de Ciências e Tecnologia Espacial

Chaboureau, Jean-Pierre

324

On free convection heat transfer with well defined boundary conditions  

SciTech Connect (OSTI)

The scaling of free convection heat transfer is investigated. The non-dimensional groups for Boussinesq and fully compressible variable property free convection, driven by isothermal surfaces, are derived using a previously published novel method of dimensional analysis. Both flows are described by a different set of groups. The applicability of each flow description is experimentally investigated for the case of the isothermal horizontal cylinder in an air-filled isothermal enclosure. The approach taken to the boundary conditions differs from that of previous investigations. Here, it is argued that the best definition of the boundary conditions is achieved for heat exchange between the cylinder and the enclosure rather than the cylinder and an arbitrarily chosen fluid region. The enclosure temperature is shown both analytically and experimentally to affect the Nusselt number. The previously published view that the Boussinesq approximation has only a limited range of application is confirmed, and the groups derived for variable property compressible free convection are demonstrated to be correct experimentally. A new correlation for horizontal cylinder Nusselt number prediction is presented.

Davies, M.R.D.; Newport, D.T.; Dalton, T.M.

1999-07-01T23:59:59.000Z

325

AERIAL MEASUREMENTS OF CONVECTION CELL ELEMENTS IN HEATED LAKES  

SciTech Connect (OSTI)

Power plant-heated lakes are characterized by a temperature gradient in the thermal plume originating at the discharge of the power plant and terminating at the water intake. The maximum water temperature discharged by the power plant into the lake depends on the power generated at the facility and environmental regulations on the temperature of the lake. Besides the observed thermal plume, cloud-like thermal cells (convection cell elements) are also observed on the water surface. The size, shape and temperature of the convection cell elements depends on several parameters such as the lake water temperature, wind speed, surfactants and the depth of the thermocline. The Savannah River National Laboratory (SRNL) and Clemson University are collaborating to determine the applicability of laboratory empirical correlations between surface heat flux and thermal convection intensity. Laboratory experiments at Clemson University have demonstrated a simple relationship between the surface heat flux and the standard deviation of temperature fluctuations. Similar results were observed in the aerial thermal imagery SRNL collected at different locations along the thermal plume and at different elevations. SRNL will present evidence that the results at Clemson University are applicable to cooling lakes.

Villa-Aleman, E; Saleem Salaymeh, S; Timothy Brown, T; Alfred Garrett, A; Malcolm Pendergast, M; Linda Nichols, L

2007-12-19T23:59:59.000Z

326

STELLAR DYNAMOS AND CYCLES FROM NUMERICAL SIMULATIONS OF CONVECTION  

SciTech Connect (OSTI)

We present a series of kinematic axisymmetric mean-field ?? dynamo models applicable to solar-type stars, for 20 distinct combinations of rotation rates and luminosities. The internal differential rotation and kinetic helicity profiles required to calculate source terms in these dynamo models are extracted from a corresponding series of global three-dimensional hydrodynamical simulations of solar/stellar convection, so that the resulting dynamo models end up involving only one free parameter, namely, the turbulent magnetic diffusivity in the convecting layers. Even though the ?? dynamo solutions exhibit a broad range of morphologies, and sometimes even double cycles, these models manage to reproduce relatively well the observationally inferred relationship between cycle period and rotation rate. On the other hand, they fail in capturing the observed increase of magnetic activity levels with rotation rate. This failure is due to our use of a simple algebraic ?-quenching formula as the sole amplitude-limiting nonlinearity. This suggests that ?-quenching is not the primary mechanism setting the amplitude of stellar magnetic cycles, with magnetic reaction on large-scale flows emerging as the more likely candidate. This inference is coherent with analyses of various recent global magnetohydrodynamical simulations of solar/stellar convection.

Dubé, Caroline; Charbonneau, Paul, E-mail: dube@astro.umontreal.ca, E-mail: paulchar@astro.umontreal.ca [Département de Physique, Université de Montréal, C.P. 6128 Succ. Centre-ville, Montréal, QC H3C 3J7 (Canada)

2013-09-20T23:59:59.000Z

327

Breakdown of large-scale circulation in turbulent rotating convection  

Science Journals Connector (OSTI)

Turbulent rotating convection in a cylinder is investigated both numerically and experimentally at Rayleigh number Ra=109 and Prandtl number ?=6.4. In this letter we discuss two topics: the breakdown under rotation of the domain-filling large-scale circulation (LSC) typical for confined convection, and the convective heat transfer through the fluid layer, expressed by the Nusselt number. The presence of the LSC is addressed for several rotation rates. For Rossby numbers Ro1.2 no LSC is found (the Rossby number indicates relative importance of buoyancy over rotation, hence small Ro indicates strong rotation). For larger Rossby numbers a precession of the LSC in anticyclonic direction (counter to the background rotation) is observed. It is shown that the heat transfer has a maximal value close to Ro=0.18 being about 15% larger than in the non-rotating case Ro=?. Since the LSC is no longer present at this Rossby value we conclude that the peak heat transfer is independent of the LSC.

R. P. J. Kunnen; H. J. H. Clercx; B. J. Geurts

2008-01-01T23:59:59.000Z

328

The convective desalination of sea ice  

E-Print Network [OSTI]

containing both liquid brine and solid (pure water) ice. Frad is the flux of penetrating solar radiation. Thus the thermal properties of sea ice are composed of those of the solid and liquid phases that make up sea ice. Fixed-salinity models used in older... components of the physical climate system. Evolving in space and time, sea ice has thermal and mechanical properties that must be updated dynamically for a faithful representation within climate models. Such models are vital tools to help people everywhere...

Rees Jones, David

2014-07-01T23:59:59.000Z

329

A numerical study of moist convection  

E-Print Network [OSTI]

by replacing the bubble or by setting the T values equal to zero whenever they became negative. The latter approach was used initially, and testing continued retaining gradual heating of the surface in the entropy field. Stability could be further enhanced... program testing was done using a 3 x 4 grid system with the equivalent of a 1C bubble imposed on the lower portion of the entropy field. The bubble allowed rapid development of the velocity field, and was employed primarily because of economy...

Hatch, James Larrien

2012-06-07T23:59:59.000Z

330

GLOBAL EXISTENCE RESULTS FOR THE ANISOTROPIC BOUSSINESQ SYSTEM IN DIMENSION TWO  

E-Print Network [OSTI]

GLOBAL EXISTENCE RESULTS FOR THE ANISOTROPIC BOUSSINESQ SYSTEM IN DIMENSION TWO RAPHA¨EL DANCHIN1 AND MARIUS PAICU2 Abstract. We study the global existence issue for the two-dimensional Boussinesq system. Introduction The Boussinesq system describes the influence of the convection (or convection

Paris-Sud XI, Université de

331

A three-dimensional numerical model of dry convection in an ambient wind field  

E-Print Network [OSTI]

effects of the ambient wind field on convection. Nost of the numerical results are shown to correspond to empirical observations, while some results are unexpected but reasonable. Nechanical and thermal energy equations have been developed... to investigate the effects on convection of an The citations on the following pages follow the tyl of th J* J of ~At * h ' f ambient wind with a vertical shear He also examined the energy interactions between convective flow and nean flows. There were many...

Burgeson, John Carl

2012-06-07T23:59:59.000Z

332

Comparisons of Two- and Three-Dimensional Convection in Type I X-ray Bursts  

E-Print Network [OSTI]

We perform the first detailed three-dimensional simulation of low Mach number convection preceding thermonuclear ignition in a mixed H/He X-ray burst. Our simulations include a moderate-sized, approximate network that captures hydrogen and helium burning up through rp-process breakout. We look in detail at the difference between two- and three-dimensional convective fields, including the details of the turbulent convection.

Zingale, M; Nonaka, A; Almgren, A S; Bell, J B

2014-01-01T23:59:59.000Z

333

Damping of Type I X-ray Burst Oscillations by Convection  

E-Print Network [OSTI]

I construct a simple model of the convective burning layer during a type I X-ray burst to investigate the effects convection has on the stability of the layer to nonradial oscillations. A linear perturbation analysis demonstrates that the region is stable to nonradial oscillations when energy transport is convection-dominated, but it is unstable when energy transport is radiation-dominated. Thus, efficient convection always dampens oscillations. These results may explain the nondetection of oscillations during the peak of some X-ray bursts.

Randall L. Cooper

2008-03-26T23:59:59.000Z

334

Numerical study of mixed convection between two corotating symmetrically heated disks  

SciTech Connect (OSTI)

This article is concerned with a numerical study of mixed convection between two symmetrically heated corotating disks. Both thermal boundary conditions of constant wall temperature and uniform heat flux are considered. By applying the boundary-layer approximation and a linear relation for density variation in centrifugal force term, the governing equations reduce to a Boussinesq system of parabolic nature. The spatially developing flow and heat transfer are studied numerically. The effects of centrifugal buoyancy, Coriolis force, radial through-flow, and wall-heating on the flow structure and heat transfer performance are examined in detail. The results reveal that the centrifugal buoyancy, which was ignored in prior studies, is indeed a significant effect in this class of rotating flows. 19 refs.

Soong, C.Y.; Yan, W.M. (Chung Cheng Inst. of Technology, Taoyuan (Taiwan, Province of China) Hua Fan Inst. of Technology, Taipei (Taiwan, Province of China))

1993-03-01T23:59:59.000Z

335

Parallel Computations of Natural Convection Flow in a Tall Cavity Using an Explicit Finite Element Method  

SciTech Connect (OSTI)

The Galerkin Finite Element Method was used to predict a natural convection flow in an enclosed cavity. The problem considered was a differentially heated, tall (8:1), rectangular cavity with a Rayleigh number of 3.4 x 10{sup 5} and Prandtl number of 0.71. The incompressible Navier-Stokes equations were solved using a Boussinesq approximation for the buoyancy force. The algorithm was developed for efficient use on massively parallel computer systems. Emphasis was on time-accurate simulations. It was found that the average temperature and velocity values can be captured with a relatively coarse grid, while the oscillation amplitude and period appear to be grid sensitive and require a refined computation.

Dunn, T.A.; McCallen, R.C.

2000-10-17T23:59:59.000Z

336

The Impact of Assimilating Surface Pressure Observations on Severe Weather Events in a WRF Mesoscale Ensemble System  

Science Journals Connector (OSTI)

Surface pressure observations are assimilated into a Weather Research and Forecast ensemble using an ensemble Kalman filter (EnKF) approach and the results are compared with observations for two severe weather events. Several EnKF experiments are ...

Dustan M. Wheatley; David J. Stensrud

2010-05-01T23:59:59.000Z

337

Mesoscale Energy Spectra of the Mei-Yu Front System. Part II: Moist Available Potential Energy Spectra  

Science Journals Connector (OSTI)

In Part II of this study, a new formulation of the spectral energy budget of moist available potential energy (MAPE) and kinetic energy is derived. Compared to previous formulations, there are three main improvements: (i) the Lorenz available ...

Jun Peng; Lifeng Zhang; Yu Luo; Chunhui Xiong

2014-04-01T23:59:59.000Z

338

CONVECTION AND DIFFERENTIAL ROTATION IN F-TYPE STARS  

SciTech Connect (OSTI)

Differential rotation is a common feature of main-sequence spectral F-type stars. In seeking to make contact with observations and to provide a self-consistent picture of how differential rotation is achieved in the interiors of these stars, we use the three-dimensional anelastic spherical harmonic (ASH) code to simulate global-scale turbulent flows in 1.2 and 1.3 M{sub Sun} F-type stars at varying rotation rates. The simulations are carried out in spherical shells that encompass most of the convection zone and a portion of the stably stratified radiative zone below it, allowing us to explore the effects of overshooting convection. We examine the scaling of the mean flows and thermal state with rotation rate and mass and link these scalings to fundamental parameters of the simulations. Indeed, we find that the differential rotation becomes much stronger with more rapid rotation and larger mass, scaling as {Delta}{Omega}{proportional_to}M {sup 3.9}{Omega}{sup 0.6}{sub 0}. Accompanying the growing differential rotation is a significant latitudinal temperature contrast, with amplitudes of 1000 K or higher in the most rapidly rotating cases. This contrast in turn scales with mass and rotation rate as {Delta}T{proportional_to}M {sup 6.4}{Omega}{sup 1.6}{sub 0}. On the other hand, the meridional circulations become much weaker with more rapid rotation and with higher mass, with their kinetic energy decreasing as KE{sub MC}{proportional_to}M {sup -1.2}{Omega}{sup -0.8}{sub 0}. Additionally, three of our simulations exhibit a global-scale shear instability within their stable regions that persists for the duration of the simulations. The flow structures associated with the instabilities have a direct coupling to and impact on the flows within the convection zone.

Augustson, Kyle C.; Toomre, Juri [JILA and Department of Astrophysical and Planetary Sciences, University of Colorado, Boulder, CO 80309 (United States); Brown, Benjamin P. [Department of Astronomy and Center for Magnetic Self-Organization (CMSO) in Laboratory and Astrophysical Plasmas, University of Wisconsin, Madison, WI 53706-1582 (United States); Brun, Allan Sacha [DSM/IRFU/SAp, CEA-Saclay and UMR AIM, CEA-CNRS-Universite Paris 7, F-91191 Gif-sur-Yvette (France); Miesch, Mark S., E-mail: Kyle.Augustson@colorado.edu [High Altitude Observatory, Center Green 1, Boulder, CO 80301 (United States)

2012-09-10T23:59:59.000Z

339

OWLeS White Paper 7/30/09 Ontario Winter Lake-effect Systems (OWLeS) Project  

E-Print Network [OSTI]

on the morphology of mesoscale precipitation; and how does the interplay between dynamics and mixed-phase cloudOWLeS White Paper 7/30/09 Ontario Winter Lake-effect Systems (OWLeS) Project Science Overview dual- polarization hydrometeor type classification of lake-effect snowfall. The proposed experimental

Geerts, Bart

340

Natural convection in high heat flux tanks at the Hanford Waste Site / [by] Mark van der Helm and Mujid S. Kazimi  

E-Print Network [OSTI]

A study was carried out on the potential for natural convection and the effect of natural convection in a High Heat Flux Tank, Tank 241-C-106, at the Hanford Reservation. To determine the existence of natural convection, ...

Van der Helm, Mark Johan, 1972-

1996-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "mesoscale convective systems" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

Generation of large-scale winds in horizontally anisotropic convection  

E-Print Network [OSTI]

We simulate three-dimensional, horizontally periodic Rayleigh-B\\'enard convection between free-slip horizontal plates, rotating about a horizontal axis. When both the temperature difference between the plates and the rotation rate are sufficiently large, a strong horizontal wind is generated that is perpendicular to both the rotation vector and the gravity vector. The wind is turbulent, large-scale, and vertically sheared. Horizontal anisotropy, engendered here by rotation, appears necessary for such wind generation. Most of the kinetic energy of the flow resides in the wind, and the vertical turbulent heat flux is much lower on average than when there is no wind.

von Hardenberg, J; Provenzale, A; Spiegel, E A

2015-01-01T23:59:59.000Z

342

The influence of convective heat transfer on flow stability in rotating disk chemical vapor deposition reactors  

SciTech Connect (OSTI)

Flow and heat transfer of NH{sub 3} and He were studied in a rotating disk system with applications to chemical vapor deposition reactors. Flow field and disk heat flux were obtained over a range of operating conditions. Comparisons of disk convective heat transfer were made to infinite rotating disk results to appraise uniformity of transport to the disk. Important operating variables include disk spin rate, disk and enclosure temperatures, flow rate, composition, pressure, and gas mixture temperature at the reactor inlet. These variables were studied over ranges of the spin Reynolds number, Re{omega}; disk mixed convection parameter, MCP{sub w}; and wall mixed convection parameter, MCP{sub w}. Results obtained for NH{sub 3} show that increasing Re{omega} from 314.5 to 3145 increases the uniformity of rotating disk heat flux and results in thinner thermal boundary layers at the disk surface. At Re{omega}=314.5, increasing MCP{sub d} to 15 leads to significant departure from the infinite disk result with nonuniform disk heat fluxes and recirculating flow patterns; flow becomes increasingly complex at larger values of MCP{sub d}. At Re{omega} of 3145, results are closer to the infinite disk for MCP{sub d} up to 15. For large negative (hot walls) and positive (cold walls) values of MCP{sub w}, flow recirculates and there is significant deviation from the infinite disk result; nonuniformities occur at both values of Re{omega}. The influence of MCP{sub w} on flow stability is increased at larger MCP{sub d} and lower Re{omega}. To determine the influence of viscosity and thermal conductivity variation with temperature, calculations were made with He and NH{sub 3}; He transport property variation is low relative to NH{sub 3}. Results show that the flow of NH{sub 3} is less stable than that of He as MCP{sub d} is increased for MCP{sub w}=0 and Re{omega}=314.5. 16 refs., 15 figs., 1 tab.

Winters, W.S.; Evans, G.H. [Sandia National Labs., Livermore, CA (United States); Grief, R. [Univ. of California, Berkeley, CA (United States). Mechanical Engineering Dept.

1997-06-01T23:59:59.000Z

343

An experimental and numerical investigation of premixed syngas combustion dynamics in mesoscale channels with controlled wall temperature profiles  

Science Journals Connector (OSTI)

Abstract The dynamics in H2/CO/O2/N2 premixed combustion was investigated experimentally and numerically in a 7-mm height mesoscale channel at atmospheric pressure, fuel–lean equivalence ratios 0.25–0.42, volumetric CO:H2 ratios 1:1 to 20:1, and wall temperatures 550–1320 K. Experiments were performed in an optically-accessible channel-flow reactor and involved high-speed (up to 1 kHz) planar laser induced fluorescence (LIF) of the OH radical and thermocouple measurements of the upper and lower channel wall temperatures. Simulations were carried out with a transient 2-D code, which included an elementary syngas reaction mechanism and detailed species transport. Demarcation of the experimentally-observed parameter space separating stationary and oscillatory combustion modes indicated that the former were favored at the higher wall temperatures and higher CO:H2 volumetric ratios, while the latter predominately appeared at the lower wall temperatures and lower CO:H2 ratios. The numerical model reproduced very well all stationary combustion modes, which included V-shaped and asymmetric (upper or lower) modes, in terms of flame shapes and flame anchoring positions. Simulations of the oscillatory flames, which appeared in the form of ignition/extinction events of varying spatial extents, were very sensitive to the specific boundary conditions and reproduced qualitatively the flame topology, the ignition sequence (including the periodic reversion from upper-asymmetric to lower-asymmetric flame propagation), and the range of measured oscillation frequencies. Predicted emissions in the stationary modes ranged from 25 to 94 ppm-mass for CO and from 0.1 to 0.3 ppm-mass for H2, while in the oscillatory modes incomplete combustion of both CO and H2 was attested during their oscillation period.

Andrea Brambilla; Marco Schultze; Christos E. Frouzakis; John Mantzaras; Rolf Bombach; Konstantinos Boulouchos

2014-01-01T23:59:59.000Z

344

Future exploration of the outer solar system  

Science Journals Connector (OSTI)

......the convection cell. (NASA/JPL-Caltech...found in the solar system, and...with relevant technology development...choice, but new technologies combining solar and chemical...crucial, with solar panel technology sufficient for......

Leigh Fletcher

2013-04-01T23:59:59.000Z

345

Variational bounds on energy dissipation in incompressible flows. III. Convection  

SciTech Connect (OSTI)

Building on a method of analysis for the Navier-Stokes equations introduced by Hopf [Math. Ann. {bold 117}, 764 (1941)], a variational principle for upper bounds on the largest possible time averaged convective heat flux is derived from the Boussinesq equations of motion. When supplied with appropriate test background fields satisfying a spectral constraint, reminiscent of an energy stability condition, the variational formulation produces rigorous upper bounds on the Nusselt number (Nu) as a function of the Rayleigh number (Ra). For the case of vertical heat convection between parallel plates in the absence of sidewalls, a simplified (but rigorous) formulation of the optimization problem yields the large Rayleigh number bound Nu{le}0.167 Ra{sup 1/2}{minus}1. Nonlinear Euler-Lagrange equations for the optimal background fields are also derived, which allow us to make contact with the upper bound theory of Howard [J. Fluid Mech. {bold 17}, 405 (1963)] for statistically stationary flows. The structure of solutions of the Euler-Lagrange equations are elucidated from the geometry of the variational constraints, which sheds light on Busse{close_quote}s [J. Fluid Mech. {bold 37}, 457 (1969)] asymptotic analysis of general solutions to Howard{close_quote}s Euler-Lagrange equations. The results of our analysis are discussed in the context of theory, recent experiments, and direct numerical simulations. {copyright} {ital 1996 The American Physical Society.}

Doering, C.R. [Center for Nonlinear Studies, MS-B258, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Center for Nonlinear Studies, MS-B258, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Constantin, P. [Department of Mathematics, University of Chicago, Chicago, Illinois 60637 (United States)] [Department of Mathematics, University of Chicago, Chicago, Illinois 60637 (United States)

1996-06-01T23:59:59.000Z

346

ARM - Midlatitude Continental Convective Clouds (jensen-sonde)  

SciTech Connect (OSTI)

A major component of the Mid-latitude Continental Convective Clouds Experiment (MC3E) field campaign was the deployment of an enhanced radiosonde array designed to capture the vertical profile of atmospheric state variables (pressure, temperature, humidity wind speed and wind direction) for the purpose of deriving the large-scale forcing for use in modeling studies. The radiosonde array included six sites (enhanced Central Facility [CF-1] plus five new sites) launching radiosondes at 3-6 hour sampling intervals. The network will cover an area of approximately (300)2 km2 with five outer sounding launch sites and one central launch location. The five outer sounding launch sites are: S01 Pratt, KS [ 37.7oN, 98.75oW]; S02 Chanute, KS [37.674, 95.488]; S03 Vici, Oklahoma [36.071, -99.204]; S04 Morris, Oklahoma [35.687, -95.856]; and S05 Purcell, Oklahoma [34.985, -97.522]. Soundings from the SGP Central Facility during MC3E can be retrieved from the regular ARM archive. During routine MC3E operations 4 radiosondes were launched from each of these sites (approx. 0130, 0730, 1330 and 1930 UTC). On days that were forecast to be convective up to four additional launches were launched at each site (approx. 0430, 1030, 1630, 2230 UTC). There were a total of approximately 14 of these high frequency launch days over the course of the experiment.

Jensen, Mike; Comstock, Jennifer; Genio, Anthony Del; Giangrande, Scott; Kollias, Pavlos

2012-01-19T23:59:59.000Z

347

Neutrino-driven convection versus advection in core collapse supernovae  

E-Print Network [OSTI]

A toy model is analyzed in order to evaluate the linear stability of the gain region immediately behind a stalled accretion shock, after core bounce. This model demonstrates that a negative entropy gradient is not sufficient to warrant linear instability. The stability criterion is governed by the ratio \\chi of the advection time through the gain region divided by the local timescale of buoyancy. The gain region is linearly stable if \\chi3, perturbations are unstable in a limited range of horizontal wavelengths centered around twice the vertical size H of the gain region. The threshold horizontal wavenumbers k_{min} and k_{max} follow simple scaling laws such that Hk_{min}\\propto 1/{\\chi} and Hk_{max}\\propto \\chi. The convective stability of the l=1 mode in spherical accretion is discussed, in relation with the asymmetric explosion of core collapse supernovae. The advective stabilization of long wavelength perturbations weakens the possible influence of convection alone on a global l=1 mode.

T. Foglizzo; L. Scheck; H. -Th. Janka

2005-07-27T23:59:59.000Z

348

LE JOURNAL DE PHYSIQUE NON BOUSSINESQ CONVECTIVE STRUCTURES IN WATER NEAR 4 C  

E-Print Network [OSTI]

LE JOURNAL DE PHYSIQUE NON BOUSSINESQ CONVECTIVE STRUCTURES IN WATER NEAR 4 °C M. DUBOIS, P. BERGE répondant à l'approximation de Boussinesq. On trouve en particulier des structures convectives hexagonales profile of such a layer produces qualitatively different behaviour from that observed in « Boussinesq

Paris-Sud XI, Université de

349

Pattern formation in binary mixture convection in cylindrical three-dimensional cells  

E-Print Network [OSTI]

present numerical results of pattern selection near the onset of convection for a water-ethanol mixture of the cell is = 11. The onset of convection occurs via a subcritical Hopf bifurcation. Slightly above ratio mixtures, S subcritical and gives rise

Batiste, Oriol

350

Lattice Boltzmann model for melting with natural convection Christian Huber a,*, Andrea Parmigiani b  

E-Print Network [OSTI]

Lattice Boltzmann model for melting with natural convection Christian Huber a,*, Andrea Parmigiani Boltzmann Heat transfer Melting Convection a b s t r a c t We develop a lattice Boltzmann method to couple and Stefan numbers) over which the correlations have been tested remains limited. The lattice Boltzmann

Manga, Michael

351

A LATTICE BOLTZMANN MODEL FOR CONVECTION HEAT TRANSFER IN POROUS MEDIA  

E-Print Network [OSTI]

A LATTICE BOLTZMANN MODEL FOR CONVECTION HEAT TRANSFER IN POROUS MEDIA Zhaoli Guo and T. S. Zhao Kong, China A lattice Boltzmann model for convection heat transfer in porous media is proposed-difference, finite-volume, and finite-element methods (e.g., [2, 3]). The lattice Boltzmann method (LBM

Zhao, Tianshou

352

Review of fluid flow and convective heat transfer within rotating disk cavities  

E-Print Network [OSTI]

1 Review of fluid flow and convective heat transfer within rotating disk cavities with impinging axial direction #12;5 Introduction Fluid flow and convective heat transfer in rotor-stator configuration heat transfer in rotor-stator configurations, which are of great importance in different engineering

Paris-Sud XI, Université de

353

Improving Convection Parameterization Using ARM Observations and NCAR Community Atmosphere Model  

SciTech Connect (OSTI)

Highlight of Accomplishments: We made significant contribution to the ASR program in this funding cycle by better representing convective processes in GCMs based on knowledge gained from analysis of ARM/ASR observations. In addition, our work led to a much improved understanding of the interaction among aerosol, convection, clouds and climate in GCMs.

Zhang, Guang J [Scripps Institution of Oceanography

2013-07-29T23:59:59.000Z

354

HEAT TRANSFERS IN A DOUBLE SKIN ROOF VENTILATED BY NATURAL CONVECTION IN SUMMER TIME  

E-Print Network [OSTI]

1 HEAT TRANSFERS IN A DOUBLE SKIN ROOF VENTILATED BY NATURAL CONVECTION IN SUMMER TIME P. H or in tropical and arid countries. In this work, radiation, convection and conduction heat transfers-dimensional numerical simulation of the heat transfers through the double skin reveals the most important parameters

Boyer, Edmond

355

Numerical study of natural convection in a vertical porous annulus with discrete heating  

E-Print Network [OSTI]

Numerical study of natural convection in a vertical porous annulus with discrete heating M. Sankar online 20 December 2010 Keywords: Natural convection Annulus Discrete heating Porous medium Radii ratio to discrete heating. The outer wall is maintained iso- thermally at a lower temperature, while the top

Lopez, John M.

356

Benchmark solution for a three-dimensional mixed convection flow -Detailed technical report  

E-Print Network [OSTI]

in many industrial applications: thermal and chemical reactors, chimneys, solar collectors, thermal-dimensional mixed convection flow in a horizontal rectangular channel heated from below and cooled from above) configuration (i.e. mixed convection flows in horizontal rectan- gular channels heated from below

Boyer, Edmond

357

THE EFFECT OF A SHEAR FLOW ON CONVECTION NEAR A TWO-DIMENSIONAL HOT-PATCH  

Science Journals Connector (OSTI)

......CONVECTION NEAR A TWO-DIMENSIONAL HOT-PATCH I. C. WALTON Department of Mathematics...takes the form of a two-dimensional hot-patch. Ingersoll's (6) results for uniform...CONVECTION NEAR A TWO-DIMENSIONAL HOT-PATCH By I. C. WALTON (Department of Mathematics......

I. C. WALTON

1985-11-01T23:59:59.000Z

358

THE MAGNETIC CONNECTION BETWEEN THE CONVECTION ZONE AND CORONA IN THE QUIET SUN  

E-Print Network [OSTI]

THE MAGNETIC CONNECTION BETWEEN THE CONVECTION ZONE AND CORONA IN THE QUIET SUN W. P. Abbett Space connection between the convectively unstable layers below the visible surface of the Sun and the overlying application of this numerical model, we present a series of simulations of the quiet Sun in a domain

Abbett, Bill

359

Impact of Convective Organization on the Response of Tropical Precipitation Extremes to Warming  

E-Print Network [OSTI]

Impact of Convective Organization on the Response of Tropical Precipitation Extremes to Warming extremes to warming in organized convection is ex- amined using a cloud-resolving model. Vertical shear, the fractional increase of precipitation extremes is similar to that of surface water vapor, which

Paris-Sud XI, Université de

360

Role of Diurnal Warm Layers in the Diurnal Cycle of Convection over the Tropical Indian Ocean during MISMO  

Science Journals Connector (OSTI)

The role of air–sea interaction in the diurnal variations of convective activity during the suppressed and developing stages of an intraseasonal convective event is analyzed using in situ observations from the Mirai Indian Ocean cruise for the ...

H. Bellenger; Y. N. Takayabu; T. Ushiyama; K. Yoneyama

2010-06-01T23:59:59.000Z

Note: This page contains sample records for the topic "mesoscale convective systems" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

Lipid-Based Nanodiscs as Models for Studying Mesoscale Coalescence A Transport Limited Case  

SciTech Connect (OSTI)

Lipid-based nanodiscs (bicelles) are able to form in mixtures of long- and short-chain lipids. Initially, they are of uniform size but grow upon dilution. Previously, nanodisc growth kinetics have been studied using time-resolved small angle neutron scattering (SANS), a technique which is not well suited for probing their change in size immediately after dilution. To address this, we have used dynamic light scattering (DLS), a technique which permits the collection of useful data in a short span of time after dilution of the system. The DLS data indicate that the negatively charged lipids in nanodiscs play a significant role in disc stability and growth. Specifically, the charged lipids are most likely drawn out from the nanodiscs into solution, thereby reducing interparticle repulsion and enabling the discs to grow. We describe a population balance model, which takes into account Coulombic interactions and adequately predicts the initial growth of nanodiscs with a single parameter i.e., surface potential. The results presented here strongly support the notion that the disc coalescence rate strongly depends on nanoparticle charge density. The present system containing low-polydispersity lipid nanodiscs serves as a good model for understanding how charged discoidal micelles coalesce.

Hu, Andrew [University of Connecticut, Storrs; Fan, Tai-Hsi [University of Connecticut, Storrs; Katsaras, John [ORNL; Xia, Yan [University of Connecticut, Storrs; Li, Ming [University of Connecticut, Storrs; Nieh, Mu-Ping [University of Connecticut, Storrs

2014-01-01T23:59:59.000Z

362

3D Simulation of Convection and Spectral Line Formation in A-type Stars  

E-Print Network [OSTI]

We present first realistic numerical simulations of 3D radiative convection in the surface layers of main sequence A-type stars with Teff = 8000 K and 8500 K, log g = 4.4 and 4.0, recently performed with the CO5BOLD radiation hydrodynamics code. The resulting models are used to investigate the structure of the H+HeI and the HeII convection zones in comparison with the predictions of local and non-local convection theories, and to determine the amount of "overshoot" into the stable layers below the HeII convection zone. The simulations also predict how the topology of the photospheric granulation pattern changes from solar to A-type star convection. The influence of the photospheric temperature fluctuations and velocity fields on the shape of spectral lines is demonstrated by computing synthetic line profiles and line bisectors for some representative examples, allowing us to confront the 3D model results with observations.

M. Steffen; B. Freytag; H. -G. Ludwig

2005-09-15T23:59:59.000Z

363

Convective heat and mass transfer and evolution of the moisture distribution in combined convection and radio frequency drying  

SciTech Connect (OSTI)

In a previous study (Dostie and Navarri, 1994), experiments indicated that a non-uniform moisture distribution could develop in radio frequency drying depending on the applied power and initial conditions, making the design and scale-up of such a dryer a more difficult task. Consequently, a thorough study of the combined convection and RF drying process was undertaken. Experimental results have shown that the values of the heat and mass transfer coefficients decrease with an increase in evaporation rate caused by RF energy. This effect is adequately taken into account by the boundary layer theory. Furthermore, the usual analogy between heat and mass transfer has been verified to apply in RF drying. Experiments have also shown that a different mass transfer resistance on both sides of the product should not result in non-uniform drying. However, it appears that non-uniform drying is dependent upon the initial moisture distribution and the relative intensity of heat transfer by convection and RF. It was shown that the maximum drying rate occurs at a higher average water content and that the total drying time increases with non-uniformity of the initial moisture distribution.

Poulin, A.; Dostie, M.; Kendall, J. [LTEE d`Hydro-Quebec, Shawinigan, Quebec (Canada); Proulx, P. [Univ. de Sherbrooke, Quebec (Canada)

1997-10-01T23:59:59.000Z

364

Orogenic Convection in Subtropical South America as Seen by the TRMM Satellite KRISTEN L. RASMUSSEN AND ROBERT A. HOUZE JR.  

E-Print Network [OSTI]

Orogenic Convection in Subtropical South America as Seen by the TRMM Satellite KRISTEN L. RASMUSSEN storms in southeastern South America are divided into three categories: storms with deep convective cores, the intense storms with wide convective cores over southeastern South America are unlike their Himalayan

Houze Jr., Robert A.

365

NUMERICAL DETERMINATION AND TREATMENT OF CONVECTIVE HEAT TRANSFER COEFFICIENT IN THE COUPLED BUILDING ENERGY AND CFD SIMULATION  

E-Print Network [OSTI]

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

Chen, Qingyan "Yan"

366

Mesoscale Simulations of Particulate Flows with Parallel Distributed Lagrange Multiplier Technique  

SciTech Connect (OSTI)

Fluid particulate flows are common phenomena in nature and industry. Modeling of such flows at micro and macro levels as well establishing relationships between these approaches are needed to understand properties of the particulate matter. We propose a computational technique based on the direct numerical simulation of the particulate flows. The numerical method is based on the distributed Lagrange multiplier technique following the ideas of Glowinski et al. (1999). Each particle is explicitly resolved on an Eulerian grid as a separate domain, using solid volume fractions. The fluid equations are solved through the entire computational domain, however, Lagrange multiplier constrains are applied inside the particle domain such that the fluid within any volume associated with a solid particle moves as an incompressible rigid body. Mutual forces for the fluid-particle interactions are internal to the system. Particles interact with the fluid via fluid dynamic equations, resulting in implicit fluid-rigid-body coupling relations that produce realistic fluid flow around the particles (i.e., no-slip boundary conditions). The particle-particle interactions are implemented using explicit force-displacement interactions for frictional inelastic particles similar to the DEM method of Cundall et al. (1979) with some modifications using a volume of an overlapping region as an input to the contact forces. The method is flexible enough to handle arbitrary particle shapes and size distributions. A parallel implementation of the method is based on the SAMRAI (Structured Adaptive Mesh Refinement Application Infrastructure) library, which allows handling of large amounts of rigid particles and enables local grid refinement. Accuracy and convergence of the presented method has been tested against known solutions for a falling sphere as well as by examining fluid flows through stationary particle beds (periodic and cubic packing). To evaluate code performance and validate particle contact physics algorithm, we performed simulations of a representative experiment conducted at the University of California at Berkley for pebble flow through a narrow opening.

Kanarska, Y

2010-03-24T23:59:59.000Z

367

EHD-based load controllers for \\{R134a\\} convective boiling heat exchangers  

Science Journals Connector (OSTI)

Abstract The objective of this study is to investigate the application of high voltage DC waveforms as a mechanism of load control for convective boiling systems. Electrohydrodynamics (EHD) induces flow pattern redistribution, which directly influences the system performance. EHD can provide a low power (<1 W), fast responding method of enhancing two phase flow systems such as heat exchangers. This study compares the use of EHD for load control with control via changing the refrigerant side flow rate in terms of required power, response time and effect on flow parameters. It was found that EHD responds faster and requires less power when a constant exit condition is required for the heat exchanger. Two EHD based controllers; PI controller and a Smith predictor were established using LabVIEW and compared in terms of their response time and regulation behaviour subject to dynamic loading. The Smith predictor resulted in less overshoot and approximately a 50% reduction in settling time in response to dynamic loading. It has been shown that this EHD based controller can regulate subject to ±25% deviation in load from the designed steady state load condition.

S. Nangle-Smith; J.S. Cotton

2014-01-01T23:59:59.000Z

368

Some properties of convective oscillations in porous medium  

SciTech Connect (OSTI)

Convective oscillations in porous media are studied numerically. A two-dimensional square, differentially heated cavity, filled with a saturated porous medium, is considered subject to linear harmonic oscillations in the vertical direction. The formulation is based on the Darcy-Boussinesq model. The problem includes three nondimensional parameters: the Rayleigh number for porous media Ra, its vibrational analog Ra{sub v}, and the nondimensional frequency f. The time-dependent Darcy-Boussinesq equations have been solved using a pseudo-spectral Chebyshev collocation method. The instantaneous fields of the established oscillatory regimes are presented. Also, some instantaneous and mean characteristics are studied and discussed. The distinctions from the case of viscous fluid alone are emphasized.

Khallouf, H.; Mojitabi, A. [Univ. Paul Sabatier, Toulouse (France); Gershuni, G.Z. [Perm State Univ. (Russian Federation). Dept. of Theoretical Physics

1996-11-08T23:59:59.000Z

369

Energy stability bounds on convective heat transport: Numerical study  

SciTech Connect (OSTI)

The concept of nonlinear energy stability has recently been extended to deduce bounds on energy dissipation and transport in incompressible flows, even for turbulent flows. In this approach an effective stability condition on {open_quotes}background{close_quotes} flow or temperature profiles is derived, which when satisfied ensures that the profile produces a rigorous upper estimate to the bulk dissipation. Optimization of the test background profiles in search of the lowest upper bounds leads to nonlinear Euler-Lagrange equations for the extremal profile. In this paper, in the context of convective heat transport in the Boussinesq equations, we describe numerical solutions of the Euler-Lagrange equations for the optimal background temperature and present the numerical computation of the implied bounds. {copyright} {ital 1997} {ital The American Physical Society}

Doering, C.R. [Department of Mathematics, University of Michigan, Ann Arbor, Michigan 48109-1109 (United States)] [Department of Mathematics, University of Michigan, Ann Arbor, Michigan 48109-1109 (United States); Hyman, J.M. [Theoretical Division and Center for Nonlinear Studies, MS-B284, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Theoretical Division and Center for Nonlinear Studies, MS-B284, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

1997-06-01T23:59:59.000Z

370

Wind reversals in turbulent Rayleigh-Benard convection  

E-Print Network [OSTI]

The phenomenon of irregular cessation and subsequent reversal of the large-scale circulation in turbulent Rayleigh-B\\'enard convection is theoretically analysed. The force and thermal balance on a single plume detached from the thermal boundary layer yields a set of coupled nonlinear equations, whose dynamics is related to the Lorenz equations. For Prandtl and Rayleigh numbers in the range $10^{-2} \\leq \\Pr \\leq 10^{3}$ and $10^{7} \\leq \\Ra \\leq 10^{12}$, the model has the following features: (i) chaotic reversals may be exhibited at Ra $\\geq 10^{7}$; (ii) the Reynolds number based on the root mean square velocity scales as $\\Re_{rms} \\sim \\Ra^{[0.41 ... 0.47]}$ (depending on Pr), and as $\\Re_{rms} \\sim \\Pr^{-[0.66 ... 0.76]}$ (depending on Ra); and (iii) the mean reversal frequency follows an effective scaling law $\\omega / (\

Francisco Fontenele Araujo; S. Grossmann; D. Lohse

2005-08-29T23:59:59.000Z

371

EFFECTS OF ASYMMETRIC FLOWS IN SOLAR CONVECTION ON OSCILLATION MODES  

SciTech Connect (OSTI)

Many helioseismic measurements suffer from substantial systematic errors. A particularly frustrating one is that time-distance measurements suffer from a large center to limb effect which looks very similar to the finite light travel time, except that the magnitude depends on the observable used and can have the opposite sign. This has frustrated attempts to determine the deep meridional flow in the solar convection zone, with Zhao et al. applying an ad hoc correction with little physical basis to correct the data. In this Letter, we propose that part of this effect can be explained by the highly asymmetrical nature of the solar granulation which results in what appears to the oscillation modes as a net radial flow, thereby imparting a phase shift on the modes as a function of observing height and thus heliocentric angle.

Baldner, Charles S.; Schou, Jesper, E-mail: baldner@stanford.edu [W.W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305-4085 (United States)

2012-11-20T23:59:59.000Z

372

Radiative-Convective Equilibrium Revisited: the Greenhouse Effect of Clouds  

Science Journals Connector (OSTI)

A parameterized spectral radiative-convective equilibrium model is built and the heating rates and temperature profiles for various absorbers are calculated and compared with the results of a classical model. Then using an optical depth that is dependent on both the extinction coefficient and the cloud-water path the validity of the black-cloud assumption is tested. It is determined under what conditions one would need to know the liquid or ice water path of the cloud and when one can simply treat the cloud as a black object. A distribution of both ice and water clouds is inputted into the model and the global average surface temperature is obtained. The sensitivity of the surface temperature to a change in either the ice or liquid water path of the cloud is also evaluated.

R. Davies; C. Radley

2009-01-01T23:59:59.000Z

373

Discharge convective instability as modifier of nonlinear hydrodynamic spectrum  

E-Print Network [OSTI]

Discharge source is considered as modifier of flow hydrodynamic spectrum. Characteristic frequency of nonlinear spectrum and spectrum power were determined under conditions of arc sliding discharge in supersonic flow. Two stages of discharge were defined: sliding stage and still stage. It was found that stage transition occurs due to convective instability of discharge. Fraction of sliding stage in overall discharge duration is determined by averaged current that is general stable discharge parameter. This phenomenon gives opportunity to control power of pressure fluctuations spectrum. Theoretical insight of field and hydrodynamic factors influencing on pulsations frequency was achieved. Hydrodynamic resistance of discharge region and holding cathode electric field turned out to be basic factors of frequency modification. Corresponding experimental verification was taken. Basic frequency law was determined for several discharge regimes.

Sergey Kamenshchikov

2012-04-26T23:59:59.000Z

374

guo-99.PDF  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Assimilation of ARM WVIOP-96 Data for an Oklahoma Assimilation of ARM WVIOP-96 Data for an Oklahoma Mesoscale Convective System Y -R. Guo, Y.-H. Kuo, J. Dudhia, and D. B. Parsons National Center for Atmospheric Research Boulder, Colorado Introduction The mesoscale observations collected during the Atmospheric Radiation Measurement (ARM) Water Vapor Intensive Observation Period (WVIOP) from September 10 to 30, 1996, provided a unique opportunity to directly assimilate heterogeneous and high-resolution observations into a state-of-art full-physics mesoscale model. The four-dimensional (4-D) variational data assimilation (4DVAR) system is based on the Pennsylvania State University-National Center for Atmospheric Research (NCAR) non-hydrostatic mesoscale model (MM5). A series of experiments were conducted for a strong

375

Section 10  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Impact of Environmental Conditions on the Mesoscale Impact of Environmental Conditions on the Mesoscale Characteristics of Squall-Line Systems: Toward the Development of Anvil Cirrus Parameterization for General Circulation Models H.-N. S. Chin and M. M. Bradley Atmospheric Sciences Division Lawrence Livermore National Laboratory Livermore, California Introduction Model and Initialization Our earlier studies (Chin 1994; Chin et al. 1995) indicated The model used is an extension of Chin and Ogura's (1989) that in the mesoscale convective systems (MCSs), a strong two-dimensional (2-D) cloud model, which is nonhydrostatic coupling exists between deep convection and its related anvil and fully compressible. The major improvements include ice cloud through the interaction among dynamical, microphysics and radiation transfer schemes for longwave

376

Research Highlight  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

The Role of Microphysics Parameterization in Simulating Tropical Mesoscale The Role of Microphysics Parameterization in Simulating Tropical Mesoscale Convective Systems Download a printable PDF Submitter: Van Weverberg, K., Brookhaven National Laboratory Vogelmann, A. M., Brookhaven National Laboratory Area of Research: Cloud Processes Working Group(s): Cloud Life Cycle Journal Reference: Van Weverberg K, AM Vogelmann, W Lin, EP Luke, AT Cialella, P Minnis, MM Khaiyer, ER Boer, and MP Jensen. 2013. "The role of cloud microphysics parameterization in the simulation of mesoscale convective system clouds and precipitation in the Tropical Western Pacific." Journal of the Atmospheric Sciences, 70(4), doi:10.1175/JAS-D-12-0104.1. The spatial distribution of cloud types at 3 UTC on 27 December 2003 as observed by GOES-9 and as simulated by the three commonly used microphysics

377

Numerical investigation of flow structure and mixed convection heat transfer of impinging radial and axial jets  

SciTech Connect (OSTI)

Mixed convection flow fields and heat transfer of partially enclosed axial and radial laminar jets impinging on a heated flat plate have been investigated from the numerical solution of incompressible unsteady Navier-Stokes and energy equations with a Boussinesq approximation. For mixed convection flow at Re = 200, steady flow has not been observed for either the radial or the axial jet. For the smallest Grashof number (Gr = 10,000), periodic solutions have been obtained. With Gr = 40,000 nonsteady nonperiodic (chaotic) flow appears. Free convection may increase that heat transfer by more than 200%.

Potthast, F.; Laschefski, H.; Mitra, N.K. (Ruhr-Univ. Bochum (Germany). Inst. fuer Thermo- und Fluiddynamik); Biswas, G. (Indian Inst. of Tech., Kanpur (India). Dept. of Mechanical Engineering)

1994-08-01T23:59:59.000Z

378

Towards a new scheme for parametrisation of deep convection in NAME III  

Science Journals Connector (OSTI)

This paper describes an updated scheme for parametrisation of atmospheric convection to be used in the Met Office Atmospheric Dispersion Model (NAME III). In this scheme, the vertical transport of particles due to convection is represented in a 1-dimensional model based on a 'mass-flux' approach. Empirical formulas are used to obtain the mass fluxes and the convective precipitation is used for closure. Results compared with the mass fluxes from the single column version of the Met Office's NWP model show good agreement. Lastly, an alternative method to estimate the mass fluxes by calculating a dilute parcel ascent is also discussed.

Elena Meneguz; David J. Thomson

2014-01-01T23:59:59.000Z

379

Transient natural convection in rectangular enclosures heated from one side and cooled from above  

SciTech Connect (OSTI)

Buoyancy-induced flows in enclosures play an important role in many engineering applications, such as heating and cooling of buildings, electronics cooling, solar energy collection systems, materials processing, energy storage systems, etc. Here, a numerical investigation into two-dimensional transient natural convection of single-phase fluids inside a completely filled square enclosure has been conducted for the Prandtl numbers of 0.71 and 7.1, and the Rayleigh number range 10{sup 3}--10{sup 7}. The fluid is assumed to be initially at a uniform temperature and motionless. Then, at time zero, the flow is driven by instantaneously raising and lowering the temperatures at the left side and the top wall, respectively. Adiabatic boundary conditions are used at the remaining walls. The unsteady Navier-Stokes equations, governing the flow under Boussinesq approximation, are solved with the vorticity-stream function formulation using the finite difference method. The development of the flow and temperature fields following these temperature changes are determined numerically. The transient behavior of the average Nusselt number at the hot wall is traced.

Aydin, O. [Karadeniz Technical Univ., Trabzon (Turkey). Dept. of Mechanical Engineering

1999-01-01T23:59:59.000Z

380

Study of formation and convective transport of aerosols using optical diagnostic technique  

E-Print Network [OSTI]

. To optimize VI performance, the characteristics of convective transport should be identified. This objective is achieved by visualization techniques. The applied visualization techniques are Mie-scattering and laser induced fluorescence (LIF). To investigate...

Kim, Tae-Kyun

2004-09-30T23:59:59.000Z

Note: This page contains sample records for the topic "mesoscale convective systems" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

A Boussinesq Model for the Convection Zone and the Solar Angular Velocity  

Science Journals Connector (OSTI)

We assume that the main mechanism responsible for setting up and driving the circulation is the interaction of rotation with convection. We solve the first-order equations (perturbation of the spherically symmetr...

G. Belvedere; L. Paternò

1976-01-01T23:59:59.000Z

382

Non-Oberbeck-Boussinesq Effects in Rayleigh-Bénard Convection of Liquids  

Science Journals Connector (OSTI)

The influence of temperature-dependent material properties on Rayleigh–Bénard convection is investigated in three different liquids, ranging from a very small Prandtl number for mercury with Pr?=?0.0232, over a m...

Susanne Horn; Olga Shishkina; Claus Wagner

2014-01-01T23:59:59.000Z

383

The excitation of solar-like oscillations in a delta Scuti star by efficient envelope convection  

E-Print Network [OSTI]

Delta Scuti (delta Sct) stars are opacity-driven pulsators with masses of 1.5-2.5M$_{\\odot}$, their pulsations resulting from the varying ionization of helium. In less massive stars such as the Sun, convection transports mass and energy through the outer 30 per cent of the star and excites a rich spectrum of resonant acoustic modes. Based on the solar example, with no firm theoretical basis, models predict that the convective envelope in delta Sct stars extends only about 1 per cent of the radius, but with sufficient energy to excite solar-like oscillations. This was not observed before the Kepler mission, so the presence of a convective envelope in the models has been questioned. Here we report the detection of solar-like oscillations in the delta Sct star HD 187547, implying that surface convection operates efficiently in stars about twice as massive as the Sun, as the ad hoc models predicted.

Antoci, V; Campante, T L; Thygesen, A O; Moya, A; Kallinger, T; Stello, D; Grigahcène, A; Kjeldsen, H; Bedding, T R; Lüftinger, T; Christensen-Dalsgaard, J; Catanzaro, G; Frasca, A; De Cat, P; Uytterhoeven, K; Bruntt, H; Houdek, G; Kurtz, D W; Lenz, P; Kaiser, A; Van Cleve, J; Allen, C; Clarke, B D

2011-01-01T23:59:59.000Z

384

Properties of a Simulated Convective Boundary Layer in an Idealized Supercell Thunderstorm Environment  

Science Journals Connector (OSTI)

Nearly all previous numerical simulations of supercell thunderstorms have neglected surface fluxes of heat, moisture, and momentum. This choice precludes horizontal inhomogeneities associated with dry boundary layer convection in the near-storm ...

Christopher J. Nowotarski; Paul M. Markowski; Yvette P. Richardson; George H. Bryan

2014-11-01T23:59:59.000Z

385

Natural convection and radiation in small enclosures with a non-attached obstruction  

E-Print Network [OSTI]

Numerical simulations were used to investigate natural convection and radiation interactions in small enclosures of both two and three-dimensional geometries. The objectives of the research were to (1) determine the relative importance of natural...

Lloyd, Jimmy Lynn

2004-09-30T23:59:59.000Z

386

Role of Convective Entrainment in Spatial Distributions of and Temporal Variations in Precipitation over Tropical Oceans  

Science Journals Connector (OSTI)

The authors demonstrate that an appropriate treatment of convective entrainment is essential for determining spatial distributions of and temporal variations in precipitation. Four numerical experiments are performed using atmospheric models with ...

Nagio Hirota; Yukari N. Takayabu; Masahiro Watanabe; Masahide Kimoto; Minoru Chikira

2014-12-01T23:59:59.000Z

387

Sensitivity of Tropical Cyclones to Parameterized Convection in the NASA GEOS5 Model  

Science Journals Connector (OSTI)

The sensitivity of tropical cyclones (TCs) to changes in parameterized convection is investigated to improve the simulation of TCs in the North Atlantic. Specifically, the impact of reducing the influence of the Relaxed Arakawa-Schubert (RAS) ...

Young-Kwon Lim; Siegfried D. Schubert; Oreste Reale; Myong-In Lee; Andrea M. Molod; Max J. Suarez

388

Urban Aerosol Impacts on Downwind Convective Storms SUSAN C. VAN DEN HEEVER AND WILLIAM R. COTTON  

E-Print Network [OSTI]

Urban Aerosol Impacts on Downwind Convective Storms SUSAN C. VAN DEN HEEVER AND WILLIAM R. COTTON. 2004; Givati and Rosenfeld 2004; Molders and Olson 2004; Jirak and Cotton 2006); 2) increased surface

Collett Jr., Jeffrey L.

389

Lattice Boltzmann Simulation of Mixed Convection in a Driven Cavity Packed with Porous Medium  

Science Journals Connector (OSTI)

The problem of mixed convection in a driven cavity packed with porous medium is studied with lattice Boltzmann method. A lattice Boltzmann model for incompressible flow in porous media and another thermal lattice

Zhenhua Chai; Zhaoli Guo; Baochang Shi

2007-01-01T23:59:59.000Z

390

Convective heat transfer in a locally heated plane incompressible fluid layer  

Science Journals Connector (OSTI)

The problem of convection in a plane horizontal layer of incompressible fluid with rigid boundaries when the temperature is ... . Together with the wellknown solutions which describe heat transfer for the linear ...

S. N. Aristov; K. G. Shvarts

2013-05-01T23:59:59.000Z

391

Unsteady hydromagnetic free-convection flow with radiative heat transfer in a rotating fluid  

Science Journals Connector (OSTI)

We study the unsteady free-convection flow near a moving infinite flat plate in a totating medium by imposing a time-dependent perturbation on a constant plate temperature. The temperatures involved are assume...

A. R. Bestman; S. K. Adjepong

392

Rheology and Convective Heat Transfer of Colloidal Gas Aphrons in Horizontal Minichannels  

E-Print Network [OSTI]

Single-phase convective heat transfer in microchannels: aand Newell, M. E. , 1967. Heat transfer in fully developed3 /s at 130 W. Water CGA Heat Transfer Coefficient, h (W/m 2

Tseng, H.; Pilon, L.; Warrier, G.

2006-01-01T23:59:59.000Z

393

Natural convection in shallow porous cavities near the density maximum: the conduction and intermediate regimes  

Science Journals Connector (OSTI)

......and to the design of solar energy collectors. Convection in shallow...where x and y are the horizontal and vertical coordinates, and u and v are the horizontal and vertical Darcy...central core regions horizontal changes will occur......

D. M. Leppinen; D. A. S. Rees

2014-06-01T23:59:59.000Z

394

Physica D 143 (2000) 169186 Surface tension-driven convection patterns in two liquid layers  

E-Print Network [OSTI]

Physica D 143 (2000) 169­186 Surface tension-driven convection patterns in two liquid layers Anne a liquid layer with a free surface is heated from below, both surface tension gradients and buoyancy may

Texas at Austin. University of

395

Tropical Cyclogenesis Sensitivity to Environmental Parameters in Radiative-Convective Equilibrium  

E-Print Network [OSTI]

In this study, the relationship between the likelihood of tropical cyclogenesis and external environmental forcings is explored in the simplest idealized modelling framework possible: radiative-convective equilibrium on a ...

Nolan, David S.

396

Changes in convective properties over the solar cycle: effect on p-mode damping rates  

Science Journals Connector (OSTI)

......Grundforskningsfond, Denmark 5 Institute for Fysik og Astronomi, Aarhus Universitet, Denmark...of 1997). 2 Computational details The basic model calculations were carried out essentially...173, Workshop on Stellar Structure: Theory and Tests of Convective Energy Transport......

G. Houdek; W.J. Chaplin; T. Appourchaux; J. Christensen-Dalsgaard; W. Däppen; Y. Elsworth; D.O. Gough; G.R. Isaak; R. New; M.C. Rabello-Soares

2001-10-21T23:59:59.000Z

397

A Multisatellite Investigation of the Convective Properties of Developing and Nondeveloping Tropical Disturbances  

Science Journals Connector (OSTI)

A comprehensive passive microwave satellite dataset is analyzed to quantify and compare the time evolution of convective properties of the pregenesis stage of developing disturbances (12 cases) and nondeveloping disturbances (3 cases), to ...

Jonathan Zawislak; Edward J. Zipser

2014-12-01T23:59:59.000Z

398

Computation of electric-arc parameters taking account of convective and radiant losses  

Science Journals Connector (OSTI)

An approximate solution of the problem of an electrical arc in a turbulent argon stream is obtained, taking into account convective and radiant energy losses in the discharge channel at atmospheric pressure.

N. A. Zyrichev

1971-10-01T23:59:59.000Z

399

Study of natural convection heat transfer above a horizontal heated plate using a laser specklegram technique  

E-Print Network [OSTI]

Heat transfer by free convection in air from an isothermal horizontal heated flat plate facing upward has been experimentally studied by using a non intrusive and accurate optical technique, Speckle photography or a specklegram technique. The local...

Cheeti, Satish K.R.

2012-06-07T23:59:59.000Z

400

Using CASA IP1 to Diagnose Kinematic and Microphysical Interactions in a Convective Storm  

Science Journals Connector (OSTI)

Data from the Collaborative Adaptive Sensing of the Atmosphere (CASA) Integrated Project I (IP1) network of polarimetric X-band radars are used to observe a convective storm. A fuzzy logic hydrometeor identification algorithm is employed to study ...

Brenda Dolan; Steven A. Rutledge

2010-05-01T23:59:59.000Z

Note: This page contains sample records for the topic "mesoscale convective systems" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

Geodynamic and seismic constraints on the thermochemical structure and dynamics of convection in the deep mantle  

Science Journals Connector (OSTI)

...Brodholt and B. J. Wood Geodynamic and seismic constraints on the thermochemical structure...by this viscosity peak. geodynamics|seismic tomography|mantle viscosity|three-dimensional...anomalies|mantle convection| Geodynamic and seismic constraints on the thermochemical structure...

2002-01-01T23:59:59.000Z

402

Numerical analysis of binary solid-liquid phase change with buoyancy and surface tension driven convection  

SciTech Connect (OSTI)

The effects of thermo/diffusocapillary convection on the solidification of aqueous NH{sub 4}Cl in a rectangular cavity have been simulated numerically using a newly developed continuum model. Diffusocapillary convection is negligible relative to thermocapillary convection, and for a 20 {times} 20 mm cavity in a one-gravity environment, thermocapillary effects are most pronounced during the early stages of solidification, when flow conditions are characterized by three major cells. One cell, driven by solutal buoyancy forces, extends from the mush region to the melt and separates top and bottom melt region cells driven primarily by surface tension and buoyancy forces, respectively. With increasing time, however, the top cell strengthens and eventually envelops the entire melt. In terms of the strength of the flow, the liquidus front morphology, and the amount of solid formed, final conditions differ only slightly from those predicted for pure thermal/solutal convection.

Incropera, F.P.; Engel, A.H.H. (Purdue Univ., Lafayette, IN (USA). Heat Transfer Lab.); Bennon, W.D. (Alcoa Technical Center, Alcoa Center, PA (US))

1989-01-01T23:59:59.000Z

403

Stratiform and Convective Precipitation Observed by Multiple Radars during the DYNAMO/AMIE Experiment  

Science Journals Connector (OSTI)

In this study, methods of convective/stratiform precipitation classification and surface rain-rate estimation based on the Atmospheric Radiation Measurement Program (ARM) cloud radar measurements were developed and evaluated. Simultaneous and ...

Min Deng; Pavlos Kollias; Zhe Feng; Chidong Zhang; Charles N. Long; Heike Kalesse; Arunchandra Chandra; Vickal V. Kumar; Alain Protat

2014-11-01T23:59:59.000Z

404

A visualization comparison of convective flow boiling heat transfer augmentation devices  

E-Print Network [OSTI]

The qualitative effects of inset-table heat transfer phics. augmentation devices on vertical in-tube convective flow boiling flow regimes, transition mechanisms, and heat transfer are presented in this study. Three twisted tapes with twist ratios...

Lundy, Brian Franklin

2012-06-07T23:59:59.000Z

405

Experimental Investigation of Forced Convection Heat Transfer of Nanofluids in a Microchannel using Temperature Nanosensors  

E-Print Network [OSTI]

Experiments were performed to study forced convective heat transfer of de-ionized water (DI water) and aqueous nanofluids flowing in a microchannel. An array of temperature nanosensors, called “Thin Film Thermocouples (TFT)”, was utilized...

Yu, Jiwon 1982-

2012-12-03T23:59:59.000Z

406

Short-wavelength geoid, bathymetry and the convective pattern beneath the Pacific Ocean  

Science Journals Connector (OSTI)

......convective pattern beneath the Pacific Ocean L. Fleitout C. Moriceau aboratoire...geoid and bathymetry data in the Pacific Ocean are used to shed new light on...various wavebands on the Central Pacific Ocean: constraints on the origin of......

L. Fleitout; C. Moriceau

1992-07-01T23:59:59.000Z

407

The Relationship between Height and Precipitation Characteristics of Summertime Convective Cells in South Florida  

Science Journals Connector (OSTI)

Radar volume scan studies employed two radars simultaneously to measure heights and other echo characteristics of convective cells. Maps produced from the date were used to identify and track cells, whose properties were then related to one ...

A. Gagin; D. Rosenfeld; R. E. López

1985-01-01T23:59:59.000Z

408

A Satellite-Based Parameter to Monitor the Aerosol Impact on Convective Clouds  

Science Journals Connector (OSTI)

A method to monitor the aerosol impact on convective clouds using satellite data is presented. The impacts of forest fires and highly polluting megacities on cloud precipitation formation processes are quantified by the vertical extent above ...

Itamar M. Lensky; Ron Drori

2007-05-01T23:59:59.000Z

409

Organization of Oceanic Convection during the Onset of the 1998 East Asian Summer Monsoon  

Science Journals Connector (OSTI)

The organizational modes of convection over the northern South China Sea (SCS) during the onset of the summer monsoon are documented using radar and sounding data from the May–June 1998 South China Sea Monsoon Experiment (SCSMEX). The onset ...

Richard H. Johnson; Steven L. Aves; Paul E. Ciesielski; Thomas D. Keenan

2005-01-01T23:59:59.000Z

410

The Distribution of Deep Convection over Ocean and Land during the Asian Summer Monsoon  

Science Journals Connector (OSTI)

Tle highly reflective cloud (HRC) dataset is a daily index of organized deep convection, at one degree resolution, from 17 years of polar-orbiting, satellite imagery. These data are used to analyze and discuss the climatological geographical ...

Robert L. Grossman; Oswaldo Garcia

1990-09-01T23:59:59.000Z

411

Multiscale Variability of Deep Convection In Realation to Large-Scale Circulation in TOGA COARE  

Science Journals Connector (OSTI)

Deep convection over the Indo–Pacific oceanic warm pool in the Tropical Ocean Global Atmosphere Coupled Ocean–Atmosphere Response Experiment (TOGA COARE) occurred in cloud clusters, which grouped together in regions favoring their occurrence. ...

Shuyi S. Chen; Robert A. Houze Jr.; Brian E. Mapes

1996-05-01T23:59:59.000Z

412

Feature-Point Detection Using Distance Transforms: Application to Tracking Tropical Convective Complexes  

Science Journals Connector (OSTI)

The identification, tracking, and statistical analysis of tropical convective complexes using satellite imagery is explored in the context of identifying feature points suitable for tracking. The feature points are determined based on the shape ...

K. I. Hodges

1998-03-01T23:59:59.000Z

413

Convective cloud and rainfall processes over the Maritime Continent : simulation and analysis of the diurnal cycle  

E-Print Network [OSTI]

The Maritime Continent experiences strong moist convection, which produces significant rainfall and drives large fluxes of heat and moisture to the upper troposphere. Despite the importance of these processes to global ...

Gianotti, Rebecca L. (Rebecca Louise)

2013-01-01T23:59:59.000Z

414

Hadley Circulations in Radiative–Convective Equilibrium in an Axially Symmetric Atmosphere  

Science Journals Connector (OSTI)

Hadley circulations in radiative–convective equilibrium are investigated using an idealistic axially symmetric model. Calculations show that the distribution of temperature in the Hadley cell is controlled by the moist process; the vertical ...

Masaki Satoh

1994-07-01T23:59:59.000Z

415

Turbulent convection in the anelastic rotating sphere : a model for the circulation on the giant planets  

E-Print Network [OSTI]

This thesis studies the dynamics of a rotating compressible gas sphere, driven by internal convection, as a model for the dynamics on the giant planets. We develop a new general circulation model for the Jovian atmosphere, ...

Kaspi, Yohai

2008-01-01T23:59:59.000Z

416

MJO and Convectively Coupled Equatorial Waves Simulated by CMIP5 Climate Models  

Science Journals Connector (OSTI)

This study evaluates the simulation of the Madden–Julian oscillation (MJO) and convectively coupled equatorial waves (CCEWs) in 20 models from the Coupled Model Intercomparison Project (CMIP) phase 5 (CMIP5) in the Intergovernmental Panel on ...

Meng-Pai Hung; Jia-Lin Lin; Wanqiu Wang; Daehyun Kim; Toshiaki Shinoda; Scott J. Weaver

2013-09-01T23:59:59.000Z

417

Pre-convective environmental conditions indicative of non-tornadic severe thunderstorm winds over Southeast Florida  

E-Print Network [OSTI]

PRE-CONVECTIVE ENVIRONMENTAL CONDITIONS INDICATIVE OF NON-TORNADIC SEVERE THUNDERSTORM WINDS OVER SOUTHEAST FLORIDA A Thesis by JEFFREY MICHAEL WILHELM Submitted to the Graduate College of Texas ARM University in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE May 1987 Major Subject: Meteorology PRE-CONVECTIVE ENVIRONMENTAL CONDITIONS INDICATIVE OF NON-TORNADIC SEVERE THUNDERSTORM WINDS OVER SOUTHEAST FLORIDA A Thesis by JEFFREY MICHAEL WILHELM Approved...

Wilhelm, Jeffrey Michael

2012-06-07T23:59:59.000Z

418

Highly Unstable Double-Diffusive Finger Convection in a Hele-Shaw Cell: Baseline Experimental Data for Evaluation of Numerical Models  

SciTech Connect (OSTI)

An experimental investigation was conducted to study double-diffusive finger convection in a Hele-Shaw cell by layering a sucrose solution over a more-dense sodium chloride (NaCl) solution. The solutal Rayleigh numbers were on the order of 60,000, based upon the height of the cell (25 cm), and the buoyancy ratio was 1.2. A full-field light transmission technique was used to measure a dye tracer dissolved in the NaCl solution. They analyze the concentration fields to yield the temporal evolution of length scales associated with the vertical and horizontal finger structure as well as the mass flux. These measures show a rapid progression through two early stages to a mature stage and finally a rundown period where mass flux decays rapidly. The data are useful for the development and evaluation of numerical simulators designed to model diffusion and convection of multiple components in porous media. The results are useful for correct formulation at both the process scale (the scale of the experiment) and effective scale (where the lab-scale processes are averaged-up to produce averaged parameters). A fundamental understanding of the fine-scale dynamics of double-diffusive finger convection is necessary in order to successfully parameterize large-scale systems.

PRINGLE,SCOTT E.; COOPER,CLAY A.; GLASS JR.,ROBERT J.

2000-12-21T23:59:59.000Z

419

Natural convection heat transfer analysis of ATR fuel elements  

SciTech Connect (OSTI)

Natural convection air cooling of the Advanced Test Reactor (ATR) fuel assemblies is analyzed to determine the level of decay heat that can be removed without exceeding the melting temperature of the fuel. The study was conducted to assist in the level 2 PRA analysis of a hypothetical ATR water canal draining accident. The heat transfer process is characterized by a very low Rayleigh number (Ra {approx} 10{sup {minus}5}) and a high temperature ratio. Since neither data nor analytical models were available for Ra < 0.1, an analytical approach is presented based upon the integral boundary layer equations. All assumptions and simplifications are presented and assessed and two models are developed from similar foundations. In one model, the well-known Boussinesq approximations are employed, the results from which are used to assess the modeling philosophy through comparison to existing data and published analytical results. In the other model, the Boussinesq approximations are not used, thus making the model more general and applicable to the ATR analysis.

Langerman, M.A.

1992-05-01T23:59:59.000Z

420

Convective Heating of the LIFE Engine Target During Injection  

SciTech Connect (OSTI)

Target survival in the hostile, high temperature xenon environment of the proposed Laser Inertial Fusion Energy (LIFE) engine is critical. This work focuses on the flow properties and convective heat load imposed upon the surface of the indirect drive target while traveling through the xenon gas. While this rarefied flow is traditionally characterized as being within the continuum regime, it is approaching transition where conventional CFD codes reach their bounds of operation. Thus ANSYS, specifically the Navier-Stokes module CFX, will be used in parallel with direct simulation Monte Carlo code DS2V and analytically and empirically derived expressions for heat transfer to the hohlraum for validation. Comparison of the viscous and thermal boundary layers of ANSYS and DS2V were shown to be nearly identical, with the surface heat flux varying less than 8% on average. From the results herein, external baffles have been shown to reduce this heat transfer to the sensitive laser entrance hole (LEH) windows and optimize target survival independent of other reactor parameters.

Holdener, D S; Tillack, M S; Wang, X R

2011-10-24T23:59:59.000Z

Note: This page contains sample records for the topic "mesoscale convective systems" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

Radial convection of finite ion temperature, high amplitude plasma blobs  

SciTech Connect (OSTI)

We present results from simulations of seeded blob convection in the scrape-off-layer of magnetically confined fusion plasmas. We consistently incorporate high fluctuation amplitude levels and finite Larmor radius (FLR) effects using a fully nonlinear global gyrofluid model. This is in line with conditions found in tokamak scrape-off-layers (SOL) regions. Varying the ion temperature, the initial blob width, and the initial amplitude, we found an FLR dominated regime where the blob behavior is significantly different from what is predicted by cold-ion models. The transition to this regime is very well described by the ratio of the ion gyroradius to the characteristic gradient scale length of the blob. We compare the global gyrofluid model with a partly linearized local model. For low ion temperatures, we find that simulations of the global model show more coherent blobs with an increased cross-field transport compared to blobs simulated with the local model. The maximal blob amplitude is significantly higher in the global simulations than in the local ones. When the ion temperature is comparable to the electron temperature, global blob simulations show a reduced blob coherence and a decreased cross-field transport in comparison with local blob simulations.

Wiesenberger, M., E-mail: Matthias.Wiesenberger@uibk.ac.at; Kendl, A. [Institute for Ion Physics and Applied Physics, Association EURATOM-ÖAW, University of Innsbruck, A-6020 Innsbruck (Austria); Madsen, J. [Association EURATOM-DTU, Department of Physics, Technical University of Denmark, 2800 Kgs. Lyngby (Denmark)

2014-09-15T23:59:59.000Z

422

Natural convection heat transfer from two horizontal cylinders  

SciTech Connect (OSTI)

Natural convection heat transfer from a single horizontal cylinder and a pair of vertically aligned horizontal cylinders is investigated. Surface heat transfer distributions around the circumference of the cylinders are presented for Rayleigh numbers of 2 x 10{sup 6}, 4 x 10{sup 6} and 6 x 10{sup 6} and a range of cylinder spacings of 1.5, 2 and 3 diameters. With a cylinder pairing the lower cylinder is unaffected by the presence of the second cylinder; the same is true of the upper cylinder if the lower one is not heated. However, when both cylinders are heated it has been found that a plume rising from the heated lower cylinder interacts with the upper cylinder and significantly affects the surface heat transfer distribution. Spectral analysis of surface heat transfer signals has established the influence of the plume oscillations on the heat transfer. Thus, when the plume from the lower cylinder oscillates out of phase with the flow around the upper cylinder it increases the mixing and results in enhanced heat transfer. (author)

Reymond, Olivier; Murray, Darina B. [Department of Mechanical and Manufacturing Engineering, Trinity College Dublin (Ireland); O'Donovan, Tadhg S. [School of Engineering and Physical Sciences, Heriot-Watt University, Nasmyth Building, Edinburgh EH14 4AS (United Kingdom)

2008-09-15T23:59:59.000Z

423

Quantitative Differences between Lightning and Nonlightning Convective Rainfall Events as Observed with Polarimetric Radar and MSG Satellite Data  

Science Journals Connector (OSTI)

To increase understanding of the relationships between lightning and nonlightning convective storms, lightning observations from the National Aeronautics and Space Administration (NASA) African Monsoon Multidisciplinary Analyses (NAMMA) campaign ...

Retha Matthee; John R. Mecikalski; Lawrence D. Carey; Phillip M. Bitzer

2014-10-01T23:59:59.000Z

424

Numerical study of natural convection in fully open tilted cavities  

SciTech Connect (OSTI)

A numerical simulation of two-dimensional laminar natural convection in a fully open tilted square cavity with an isothermally heated back wall is conducted. The remaining two walls of the cavity are adiabatic. Steady-state solutions are presented for Grashof numbers between 10{sup 2} and 10{sup 5} and for tilt angles ranging from {minus}60{degree} to 90{degree} (where 90{degree} represents a cavity with the opening facing down). The fluid properties are assumed to be constant except for the density variation with temperature that gives rise to the buoyancy forces, which is treated by the Boussinesq approximation. The fluid concerned is air with Prandtl number fixed at 0.71. The governing equations are expressed in a normalized primitive variables formulation. Numerical predictions of the velocity and temperature fields are obtained using the finite-volume-based power law (SIMPLER: Semi-Implicit Method for Pressure-Linked Equations Revised) algorithm. For a vertical open cavity ({alpha} = 0{degree}), the algorithm generated results that were in good agreement with those previously published. Flow patterns and isotherms are shown in order to give a better understanding of the heat transfer and flow mechanisms inside the cavity. Effects of the controlling parameters-Grashof number and tilt angle-on the heat transfer (average Nusselt number) are presented and analyzed. The results also revealed that the open-cavity Nusselt number approaches the flat-plate solution when either Grashof number or tilt angle increases. In addition, a correlation of the Nusselt number in terms of the Grashof number and tilt angle is developed and presented; a comparison is made with available data from other literature.

Elsayed, M.M.; Al-Najem, N.M.; El-Refaee, M.M.; Noor, A.A.

1999-09-01T23:59:59.000Z

425

A multi-scale framework for CFD modelling of multi-phase complex systems based on the EMMS approach  

Science Journals Connector (OSTI)

The averaged conservative equations in CFD modelling are inadequate to achieve a complete description of the multi-scale structures in multiphase complex systems. By considering the relationship between meso-scale structures and meso-scale energy consumption, stability conditions mathematically expressed as a mutually constrained extremum are proposed in the Energy-Minimization Multi-Scale (EMMS) approach and indispensable to reflect the compromise of different dominant mechanisms for various multiphase systems. The approach is first applied to global systems to predict and physically interpret the macro-scale structure evolution, i.e., regime transition. Then when applied to computational cells, it corrects interphase momentum transfer and greatly improves the accuracy of coarse-grid CFD simulation.

Ning Yang

2012-01-01T23:59:59.000Z

426

Numerical Modeling Studies of The Dissolution-Diffusion-Convection ProcessDuring CO2 Storage in Saline Aquifers  

SciTech Connect (OSTI)

For purposes of geologic storage, CO2 would be injected into saline formations at supercritical temperature and pressure conditions, and would form a separate phase that is immiscible with the aqueous phase (brine). At typical subsurface temperature and pressure conditions, supercritical CO2 (scCO2) has lower density than the aqueous phase and would experience an upward buoyancy force. Accordingly, the CO2 is expected to accumulate beneath the caprock at the top of the permeable interval, and could escape from the storage formation wherever (sub-)vertical pathways are available, such as fractures or faults through the caprock, or improperly abandoned wells. Over time, an increasing fraction of CO2 may dissolve in the aqueous phase, and eventually some of the aqueous CO2 may react with rock minerals to form poorly soluble carbonates. Dissolution into the aqueous phase and eventual sequestration as carbonates are highly desirable processes as they would increase permanence and security of storage. Dissolution of CO2 will establish phase equilibrium locally between the overlying CO2 plume and the aqueous phase beneath. If the aqueous phase were immobile, CO2 dissolution would be limited by the rate at which molecular diffusion can remove dissolved CO2 from the interface between CO2-rich and aqueous phases. This is a slow process. However, dissolution of CO2 is accompanied by a small increase in the density of the aqueous phase, creating a negative buoyancy force that can give rise to downward convection of CO2-rich brine, which in turn can greatly accelerate CO2 dissolution. This study explores the process of dissolution-diffusion-convection (DDC), using high-resolution numerical simulation. We find that geometric features of convection patterns are very sensitive to small changes in problem specifications, reflecting self-enhancing feedbacks and the chaotic nature of the process. Total CO2 dissolution rates on the other hand are found to be quite robust against modest changes in problem parameters, and are essentially constant as long as no dissolved CO2 reaches the lower boundary of the system.

Pruess, Karsten; Zhang, Keni

2008-11-17T23:59:59.000Z

427

Critical role for mesoscale eddy diffusion in supplying oxygen to hypoxic ocean waters1 Anand Gnanadesikan*3  

E-Print Network [OSTI]

by the current generation of Earth System Models. Using satellite-based22 estimate of oxygen consumption 1000 m2 /s. Varying Aredi across a suite24 of Earth System Models yields a broadly consistent result with about 1/3 of these waters39 dropping below 10 M (solid black line, Fig. 1c,d).40 The Earth System Models

Gnanadesikan, Anand

428

Inverse natural convection problem of estimating wall heat flux using a moving sensor  

SciTech Connect (OSTI)

Inverse heat transfer problems have many applications in various branch of science and engineering. Here, the inverse problem of determining heat flux at the bottom wall of a two-dimensional cavity from temperature measurement in the domain is considered. The Boussinesq equation is used to model the natural convection induced by the wall heat flux. The inverse natural convection problem is posed as a minimization problem of the performance function, which is the sum of square residuals between calculated and observed temperature, by means of a conjugate gradient method. Instead of employing several fixed sensors, a single sensor is used which is moving at a given frequency over the bottom wall. The present method solves the inverse natural convection problem accurately without a priori information about the unknown function to be estimated.

Park, H.M.; Chung, O.Y.

1999-11-01T23:59:59.000Z

429

Natural convection with mixed insulating and conducting boundary conditions: low and high Rayleigh numbers regimes  

E-Print Network [OSTI]

We investigate the stability and dynamics of natural convection in two dimensions, subject to inhomogeneous boundary conditions. In particular, we consider a Rayleigh-B\\`enard (RB) cell, where the horizontal top boundary contains a periodic sequence of alternating thermal insulating and conducting patches, and we study the effects of the heterogeneous pattern on the global heat exchange, both at low and high Rayleigh numbers. At low Rayleigh numbers, we determine numerically the transition from a regime characterized by the presence of small convective cells localized at the inhomogeneous boundary to the onset of bulk convective rolls spanning the entire domain. Such a transition is also controlled analytically in the limit when the boundary pattern length is small compared with the cell vertical size. At higher Rayleigh number, we use numerical simulations based on a lattice Boltzmann method to assess the impact of boundary inhomogeneities on the fully turbulent regime up to $Ra \\sim 10^{10}$.

Ripesi, P; Sbragaglia, M; Wirth, A

2014-01-01T23:59:59.000Z

430

On the Features of Radiative and Convective Regimes Under the Cumulus Cloudiness  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

On the Features of Radiative and Convective Regimes On the Features of Radiative and Convective Regimes Under the Cumulus Cloudiness B. M. Koprov, V. M. Koprov, G. S. Golitsyn A.M. Oboukhov Institute of Atmospheric Physics Moscow, Russia E. N. Kadygrov, A. V. Koldaev Central Aerological Observatory Dolgoprudny, Russia Introduction The study of instant temperature field transformation, convective and radiative regime perturbation within the layer of 0 to 650 m was fulfilled as caused by cloud modulation of solar radiation flux. It was made within the scope of Zvenigorod Atmospheric Radiation Measurement (ARM) experiments in 2001 and 2002. Instrumentation The equipment used: 1. Microwave temperature profiler designed in Central Aerological Observatory (CAO) and manufactured by Russian company ATTEX (Kadygrov and Pick 1998).

431

Non-Oberbeck-Boussinesq Effects in Gaseous Rayleigh-Bénard Convection  

Science Journals Connector (OSTI)

Non-Oberbeck-Boussinesq (NOB) effects are measured experimentally and calculated theoretically for strongly turbulent Rayleigh-Bénard convection of ethane gas under pressure where the material properties strongly depend on the temperature. Relative to the Oberbeck-Boussinesq case we find a decrease of the central temperature as compared to the arithmetic mean of the top- and bottom-plate temperature and an increase of the Nusselt number. Both effects are of opposite sign and greater magnitude than those for NOB convection in liquids like water.

Guenter Ahlers; Francisco Fontenele Araujo; Denis Funfschilling; Siegfried Grossmann; Detlef Lohse

2007-01-29T23:59:59.000Z

432

Statistics and scaling properties of temperature field in symmetrical non-Oberbeck-Boussinesq turbulent convection  

E-Print Network [OSTI]

The influence of symmetrical non-Oberbeck-Boussinesq (SNOB) effect on statistical and scaling properties of temperature field in turbulent convection is investigated experimentally in $SF_{6}$ in the vicinity of its gas-liquid critical point (CP). The main conclusion of the studies is that besides the strong $Ra$ and $Pr$ dependence of the rms of temperature fluctuations normalized by the temperature difference across the cell, different from the Oberbeck-Boussinesq (OB) case of turbulent convection, all rest of statistical and scaling properties of temperature field discussed in details are the same as in the OB case.

Yuri Burnishev; Victor Steinberg

2011-08-31T23:59:59.000Z

433

Numerical study of pattern formation following a convective instability in non-Boussinesq fluids  

Science Journals Connector (OSTI)

We present a numerical study of a model of pattern formation following a convective instability in a non-Boussinesq fluid. It is shown that many of the features observed in convection experiments conducted on CO2 gas can be reproduced by using a generalized two-dimensional Swift-Hohenberg equation. The formation of hexagonal patterns, rolls, and spirals is studied, as well as the transitions and competition among them. We also study nucleation and growth of hexagonal patterns and find that the front velocity in this two-dimensional model is consistent with the prediction of marginal stability theory for one-dimensional fronts.

Hao-wen Xi; Jorge Viñals; J. D. Gunton

1992-10-15T23:59:59.000Z

434

Atmospheric structure and variability in areas of convective storms determined from 3-h rawinsonde data  

E-Print Network [OSTI]

changes in TTI determined from charts in Fig. 58. . 101 60 61 62 Cumulative frequency distributions of changes in TTI in AVE II . . ~ . . . . . ~ Surface analysis at 2100 GMT, 11 May 1974 Satellite and radar composite at 2200 GMT, 11 May 1974 102... change in the probability of convective activity by a factor of 8 or more in 3 h. Between 30% and 60% of the total changes in parameters associated with convective activity over a 12-h period is shown to take place during a 3-h period. These large...

Wilson, Gregory Sims

2012-06-07T23:59:59.000Z

435

A new predictive dynamic model describing the effect of1 the ambient temperature and the convective heat transfer2  

E-Print Network [OSTI]

and the convective heat transfer2 coefficient on bacterial growth3 4 H. Ben Yaghlenea,b* , I. Leguerinela , M. Hamdib Ratkowsky "square root" model and a simplified two-parameter20 heat transfer model regarding an infinite air temperature, the convective heat transfer22 coefficient and the growth parameters of the micro

Paris-Sud XI, Université de

436

Magnetic buoyancy instabilities in the presence of magnetic flux pumping at the base of the solar convection zone  

Science Journals Connector (OSTI)

......in a model of the solar tachocline. In particular...therefore the kinetic energy of the shear is not...for a primordial solar magnetic field...similar mean kinetic energy density as the convection...convection zone and to the solar surface. One important...be seen as a pilot project which has the limited......

Adrian J. Barker; Lara J. Silvers; Michael R. E. Proctor; Nigel O. Weiss

2012-07-21T23:59:59.000Z

437

CRYSTALLINE SILICON THIN-FILM SOLAR CELLS FROM THE POROUS SILICON PROCESS APPLYING CONVECTION ASSISTED CHEMICAL VAPOR DEPOSITION  

E-Print Network [OSTI]

CRYSTALLINE SILICON THIN-FILM SOLAR CELLS FROM THE POROUS SILICON PROCESS APPLYING CONVECTION ASSISTED CHEMICAL VAPOR DEPOSITION Barbara Terheiden,1* Thomas Kunz,2 Ingo Burkert2 , Renate Horbelt,1, D-91058 Erlangen, Germany ABSTRACT: Convection assisted chemical vapor deposition (CoCVD) is applied

438

Unsteady MHD combined convection over a moving vertical sheet in a fluid saturated porous medium with uniform surface heat flux  

Science Journals Connector (OSTI)

The group transformation method is applied for solving the combined convection problem in an unsteady, two-dimensional, laminar, boundary-layer flow of a viscous, incompressible and electrically-conducting fluid along a vertical continuous moving plate ... Keywords: Flow, Group transformation method, MHD, Natural convection, Porous medium

S. M. M. El-Kabeir; A. M. Rashad; Rama Subba Reddy Gorla

2007-08-01T23:59:59.000Z

439

Group solution for unsteady free-convection flow from a vertical moving plate subjected to constant heat flux  

Science Journals Connector (OSTI)

The problem of heat and mass transfer in an unsteady free-convection flow over a continuous moving vertical sheet in an ambient fluid is investigated for constant heat flux using the group theoretical method. The nonlinear coupled partial differential ... Keywords: 22E05, 35Q53, 54H15, Free convective flow, Group theoretic method, Prandtl number, Thermal boundary layer

M. Kassem

2006-03-01T23:59:59.000Z

440

Measurements of Heavy Convective Rainfall in the Presence of Hail in Flood-Prone Areas Using an X-Band Polarimetric Radar  

Science Journals Connector (OSTI)

The utility of X-band polarimetric radar to provide rainfall estimations with high spatial and temporal resolution in heavy convective precipitation in the presence of hail is explored. A case study involving observations of strong convective ...

Sergey Y. Matrosov; Robert Cifelli; David Gochis

2013-02-01T23:59:59.000Z

Note: This page contains sample records for the topic "mesoscale convective systems" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

VoLUME 57, NUM@BR 16 PHYSICAL REVIEW LETTERS 20 OcToBER 1986 Competing Patterns in a Convective Binary Mixture  

E-Print Network [OSTI]

of convection in ethanol-water mixtures at positive values of the separation ratio Q are presented. Close-driven convection in ethanol-water mixtures. The Soret effect is a mechanism by which an externally imposed tempera

Moses, Elisha

442

Proceedings of the ASME Heat Transfer Division. Volume 4: Natural convection within a horizontal circular cylinder heated from below and cooled from above; Numerical methods for coupled fluid-thermal-structural interaction; Thermal analysis in waste processing and disposal; Heat transfer in fire and combustion systems; HTD-Volume 335  

SciTech Connect (OSTI)

The first two sections as listed in the title contain 7 papers. The third section on thermal analysis contains 18 papers arranged into the following topical areas: Thermal treatment and municipal wastes; Thermal hydraulics in hazardous and nuclear waste processing and disposal; and Waste processing. Heat transfer in fire and combustion systems contains 17 papers arranged into the following topical sections: Soot/radiation; Combustion systems; Multiphase combustion; and Flames and fires. Most papers have been processed separately for inclusion on the data base.

Pepper, D.W. [ed.] [Univ. of Nevada, Las Vegas, NV (United States); Douglass, R.W. [ed.] [Idaho National Engineering Lab., Idaho Falls, ID (United States); Heinrich, J.C. [ed.] [Univ. of Arizona, Tucson, AZ (United States)] [and others

1996-12-31T23:59:59.000Z

443

NREL: Systems Engineering - 2013 Wind Energy Systems Engineering...  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

with creating a multi-fidelity framework for optimization of onshore and offshore wind farms. The second involves mesoscale wake effects for studying the effects of entire...

444

Natural circulating passive cooling system for nuclear reactor containment structure  

DOE Patents [OSTI]

A passive cooling system for the contaminant structure of a nuclear reactor plant providing protection against overpressure within the containment attributable to inadvertent leakage or rupture of the system components. The cooling system utilizes natural convection for transferring heat imbalances and enables the discharge of irradiation free thermal energy to the atmosphere for heat disposal from the system.

Gou, Perng-Fei (Saratoga, CA); Wade, Gentry E. (Saratoga, CA)

1990-01-01T23:59:59.000Z

445

Passive cooling system for nuclear reactor containment structure  

DOE Patents [OSTI]

A passive cooling system for the contaminant structure of a nuclear reactor plant providing protection against overpressure within the containment attributable to inadvertent leakage or rupture of the system components. The cooling system utilizes natural convection for transferring heat imbalances and enables the discharge of irradiation free thermal energy to the atmosphere for heat disposal from the system.

Gou, Perng-Fei (Saratoga, CA); Wade, Gentry E. (Saratoga, CA)

1989-01-01T23:59:59.000Z

446

Latent heating contribution from precipitation systems with different sizes, depths and intensities in the tropics  

Science Journals Connector (OSTI)

Latent Heating (LH) from precipitation systems with different sizes, depths and convective intensities are quantified with 15 years of LH retrievals from Version 7 Precipitation Radar (PR) products of the Tropical Rainfall Measuring Mission (TRMM)...

Chuntao Liu; Shoichi Shige; Yukari N. Takayabu; Edward Zipser

447

Effect of a horizontal magnetic field on convective instabilities in mercury  

E-Print Network [OSTI]

L-455 Effect of a horizontal magnetic field on convective instabilities in mercury S. Fauve, C on the three-dimensional instabilities which occur in a Rayleigh-Bénard experiment with mercury is studied which occur in a Rayleigh-Benard experi- ment in mercury, a low Prandtl number fluid. (The Prandtl

Boyer, Edmond

448

Non-Oberbeck-Boussinesq Effects in Gaseous Rayleigh-Benard Convection Guenter Ahlers,1  

E-Print Network [OSTI]

Non-Oberbeck-Boussinesq Effects in Gaseous Rayleigh-Be´nard Convection Guenter Ahlers,1 Francisco December 2006; published 29 January 2007) Non-Oberbeck-Boussinesq (NOB) effects are measured experimentally where the material properties strongly depend on the temperature. Relative to the Oberbeck-Boussinesq

Ahlers, Guenter

449

Non-Oberbeck-Boussinesq effects in three-dimensional Rayleigh-Bénard convection  

Science Journals Connector (OSTI)

To study the classical problem of Rayleigh-Bénard convection, i.e. a fluid layer confined between a heating-plate at the bottom and a cooling-plate at the top, a common assumption is that all material properti...

Susanne Horn; Olga Shishkina; Claus Wagner

2011-01-01T23:59:59.000Z

450

Dynamic RadiativeConvective Equilibria Using GCM Column Physics ISAAC M. HELD  

E-Print Network [OSTI]

Dynamic Radiative­Convective Equilibria Using GCM Column Physics ISAAC M. HELD NOAA and Oceanic Sciences, Department of Geosciences, Princeton University, Princeton, New Jersey BRUCE WYMAN NOAA author address: Dr. Isaac M. Held, NOAA/Geo- physical Fluid Dynamics Laboratory, Princeton University

451

Compact fluorescent lamp using horizontal and vertical insulating septums and convective venting geometry  

DOE Patents [OSTI]

A novel design is described for a compact fluorescent lamp, including a lamp geometry which will increase light output and efficacy of the lamp in a base down operating position by providing horizontal and vertical insulating septums positioned in the ballast compartment of the lamp to provide a cooler coldspot. Selective convective venting provides additional cooling of the ballast compartment. 9 figs.

Siminovitch, M.

1998-02-10T23:59:59.000Z

452

Lattice Boltzmann simulations of a time-dependent natural convection problem  

E-Print Network [OSTI]

Lattice Boltzmann simulations of a time-dependent natural convection problem Beno^it Trouette September 2, 2013 Abstract A two-dimensional double Multiple-Relaxation-Time thermal lattice Boltzmann-dependent flows as well as the space and time convergence orders. Keywords: Thermal lattice Boltzmann method

Boyer, Edmond

453

TACKLEY ET AL.:THERMO-CHEMICAL PHILOSOPHY Numerical and laboratory studies of mantle convection: Philosophy,  

E-Print Network [OSTI]

TACKLEY ET AL.:THERMO-CHEMICAL PHILOSOPHY 1 Numerical and laboratory studies of mantle convection: Philosophy, accomplishments and thermo-chemical structure and evolution Paul J. Tackley Department of Earth how the solid parts of Earth and other terrestrial planets work. Here, the general philosophy

Tackley, Paul J.

454

Numerical computation of 3D heat transfer in complex parallel convective exchangers using generalized Graetz modes  

E-Print Network [OSTI]

Numerical computation of 3D heat transfer in complex parallel convective exchangers using insights into the most con- tributing structure to exchanges and transfers. Several examples of heat, whilst many other can be found in a recent review [12]. As quoted in [12] conjugate heat transfer

Paris-Sud XI, Université de

455

Natural convection in tunnels at Yucca Mountain and impact on drift seepage  

SciTech Connect (OSTI)

The decay heat from radioactive waste that is to be disposed in the once proposed geologic repository at Yucca Mountain (YM) will significantly influence the moisture conditions in the fractured rock near emplacement tunnels (drifts). Additionally, large-scale convective cells will form in the open-air drifts and will serve as an important mechanism for the transport of vaporized pore water from the fractured rock in the drift center to the drift end. Such convective processes would also impact drift seepage, as evaporation could reduce the build up of liquid water at the tunnel wall. Characterizing and understanding these liquid water and vapor transport processes is critical for evaluating the performance of the repository, in terms of water-induced canister corrosion and subsequent radionuclide containment. To study such processes, we previously developed and applied an enhanced version of TOUGH2 that solves for natural convection in the drift. We then used the results from this previous study as a time-dependent boundary condition in a high-resolution seepage model, allowing for a computationally efficient means for simulating these processes. The results from the seepage model show that cases with strong natural convection effects are expected to improve the performance of the repository, since smaller relative humidity values, with reduced local seepage, form a more desirable waste package environment.

Halecky, N.; Birkholzer, J.T.; Peterson, P.

2010-04-15T23:59:59.000Z

456

Marangoni convection induced by a nonlinear temperature-dependent surface tension  

E-Print Network [OSTI]

23 Marangoni convection induced by a nonlinear temperature-dependent surface tension A. Cloot and G'instabilité de Marangoni dans une mince lame horizontale de fluide lorsque la tension de surface est une fonction ofthe surface- tension with respect to the temperature is studied. This behaviour is typical of some

Paris-Sud XI, Université de

457

Time-independent square patterns in surface-tension-driven Benard convection  

E-Print Network [OSTI]

Time-independent square patterns in surface-tension-driven Be´nard convection Michael F. Schatza The transition between hexagonal and square patterns is investigated in laboratory experiments on surface-tension, the transition from hexagons to other patterns was unexplored for the surface-tension-driven regime of Be

Texas at Austin. University of

458

Convection in Arc Weld Pools Electromagnetic and surface tension forces are shown to  

E-Print Network [OSTI]

Convection in Arc Weld Pools Electromagnetic and surface tension forces are shown to dominate flow tension forces. It is shown that the electromag- netic and surface tension forces domi- nate the flow by experimental measurements of segrega- tion in the weld pool. It is also shown that the surface tension driven

Eagar, Thomas W.

459

Simulation and Cryogenic Experiments of Natural Convection for the Titan Montgolfiere  

E-Print Network [OSTI]

Simulation and Cryogenic Experiments of Natural Convection for the Titan Montgolfiere Yuri Feldman for prediction of the buoyancy of single- and double- walled balloons in a cryogenic environment such as Titan at cryogenic conditions. The predicted buoyancy and temperature fields compare favorably with experiments

Dabiri, John O.

460

Lightning flash rate and chemistry simulation of tropical island convection using a cloud-resolved model  

E-Print Network [OSTI]

Lightning flash rate and chemistry simulation of tropical island convection using a cloud schemes (FRPSs) and estimating the average NO production per lightning flash in this unique storm type network (LINET) provided lightning flash data for the model and a lightning placement scheme injected

Maryland at College Park, University of

Note: This page contains sample records for the topic "mesoscale convective systems" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


461

Three-dimensional simulations of the upper radiation–convection transition layer in subgiant stars  

Science Journals Connector (OSTI)

......University of Science Technology, Hong Kong...subgiant of one solar mass and a lower-gravity...of convection cell sizes. Differences...contrast with 2 106 cells observed on the solar surface. Observations...800 times the solar radius (Gray...approximately 600 cells would be needed......

F. J. Robinson; P. Demarque; L. H. Li; S. Sofia; Y.-C. Kim; K. L. Chan; D. B. Guenther

2004-02-01T23:59:59.000Z

462

Testing turbulent convection theory in solar models – II. Solar p-mode oscillations  

Science Journals Connector (OSTI)

......Reynolds number in the solar convection zone makes the turbulent energy spectrum greatly...and concluded that solar models considering...turbulent kinetic energy could result in better...turbulence in our solar models in the present...of China through project number 10303007......

J. Y. Yang; Y. Li

2007-02-11T23:59:59.000Z

463

Eects of convection instability due to incompatibility between ocean dynamics and surface forcings  

E-Print Network [OSTI]

- bility between a surface temperature climatology and a given ocean model, into which the climatology by thermal and wind forcing only. Initially, the temperature climatology is forcefully assimilated climatology. In areas characterized by sharp oceanic fronts and high convective activity, the OGCM, due

Paris-Sud XI, Université de

464

Three Dimensional Simulation of Rayleigh-Bénard Convection for Rapid Microscale Polymerase Chain Reaction  

E-Print Network [OSTI]

Rayleigh-Bénard convection has been extensively studied in literature owing to its ubiquitous nature. However, most of the studies have been confined to geometries where the aspect ratio of the cylinder was less than 1. Here we study the motion...

Muddu, Radha Malini Gowri

2012-02-14T23:59:59.000Z

465

Using CASA IP1 to Diagnose Kinematic and Microphysical Interactions in a Convective Storm  

E-Print Network [OSTI]

bulk hydrometeor identification and dual-Doppler wind retrievals. Comparisons are made with the nearby-band radars are used to observe a convective storm. A fuzzy logic hydrometeor identification algorithm the type of echoes in the network based on storm identification al- gorithms, then allocates radars

Rutledge, Steven

466

Can a Convective Cloud Feedback Help to Eliminate Winter Sea Ice at High CO2 Concentrations?  

E-Print Network [OSTI]

have remote effects on global climate as well. Accurate forecasting of winter sea ice has significantCan a Convective Cloud Feedback Help to Eliminate Winter Sea Ice at High CO2 Concentrations? DORIAN) ABSTRACT Winter sea ice dramatically cools the Arctic climate during the coldest months of the year and may

Tziperman, Eli

467

Influence of Sea Surface Temperature on Humidity and Temperature in the Outflow of Tropical Deep Convection  

E-Print Network [OSTI]

-Service Aircraft (MOZAIC) project are analyzed in the vicinity of deep convective outflow to study the variationsInfluence of Sea Surface Temperature on Humidity and Temperature in the Outflow of Tropical Deep upper-tropospheric temperature and humidity by the Mea- surement of Ozone and Water Vapor by Airbus In

Johnson, Richard H.

468

Do the Tallest Convective Cells over the Tropical Ocean Have Slow Updrafts?  

Science Journals Connector (OSTI)

Far from continents, a few storms lift precipitation-size ice particles into the stratosphere, 17 to 18 km above the tropical ocean. This study is the first to examine the observed properties of a large sample of these extremely tall convective ...

Owen A. Kelley; John Stout; Michael Summers; Edward J. Zipser

2010-05-01T23:59:59.000Z

469

10.12 CONVECTION INITIATION AND MISOCYCLONE DEVELOMENT: IS THERE A LINK ?  

E-Print Network [OSTI]

Kingsmill·, and Carl Young £ · University of Colorado, CIRES, Boulder, Colorado Desert Research Institute to horizontal shear instabilities can produce wave pattern that produce small scale ( 4 km) vertical vortic- ity with the initiation of deep convection along the Florida Peninsula using a net- work of anemometers. Since

470

Magneto-convective models of red dwarfs: constraints imposed by the lithium abundance  

E-Print Network [OSTI]

Magnetic fields impede the onset of convection, thereby altering the thermal structure of a convective envelope in a low mass star: this has an effect on the amount of lithium depletion in a magnetized star. In order to quantify this effect, we have applied a magneto-convective model to two low mass stars for which lithium abundances and precise structural parameters are known: YY Gem and CU Cnc. For both stars, we have obtained models which satisfy empirical constraints on the following parameters: R, L, surface magnetic field strength, and Li abundance. In the case of YY Gem, we have obtained a model which satisfies the empirical constraints with an internal magnetic field of several megagauss: such a field strength is within the range of a dynamo where the field energy is in equipartition with rotational energy deep inside the convection zone. However, in the case of CU Cnc, the Li requires an internal magnetic field which is probably too strong for a dynamo origin: we suggest possible alternatives which m...

MacDonald, J

2015-01-01T23:59:59.000Z

471

The performance of PEM fuel cells fed with oxygen through the free-convection mode  

E-Print Network [OSTI]

The performance of PEM fuel cells fed with oxygen through the free-convection mode Pei-Wen Li; accepted 27 September 2002 Abstract The feasibility and restrictions of feeding oxygen to a PEM fuel cell in the fuel cell. Experimental tests were conducted for one PEM fuel cell stack and two single PEM fuel cell

472

A FULL SCALE ROOM FOR THE EXPERIMENTAL STUDY OF INTERIOR BUILDING CONVECTIVE HEAT TRANSFER  

E-Print Network [OSTI]

air flow measurement. A water source heat pump provided chilled water to a fan-coil unit which in turn on volumetric air flow measurement and an overall room heat balance. Analysis was directed at results fromA FULL SCALE ROOM FOR THE EXPERIMENTAL STUDY OF INTERIOR BUILDING CONVECTIVE HEAT TRANSFER: DESIGN

473

Mantle convection with strong subduction zones Clinton P. Conrad* and Bradford H. Hager  

E-Print Network [OSTI]

for convection, which includes an expression for the energy needed to deform the oceanic lithosphere the entire oceanic lithosphere, subduction is an ef®cient mechanism for converting the signi®cant negative method for implementing subduction that parametrizes the deformation of the oceanic lithosphere within

Conrad, Clint

474

BUBBLE CHARACTERISTICS AND CONVECTIVE EFFECTS IN THE FLOW BOILING HEAT TRANSFER OF BINARY MIXTURES  

E-Print Network [OSTI]

BUBBLE CHARACTERISTICS AND CONVECTIVE EFFECTS IN THE FLOW BOILING HEAT TRANSFER OF BINARY MIXTURES on the bubble growth and associated heat transfer phenomena. The present work focuses on obtaining the bubble. The bubble growth is observed using a high speed camera (1000 fps) under a magnification of 290X. The bubble

Kandlikar, Satish

475

Movement of oxygen from the atmosphere to the mitochondria occurs via several convective and diffusive steps  

E-Print Network [OSTI]

4111 Movement of oxygen from the atmosphere to the mitochondria occurs via several convective and diffusive steps (Weibel et al., 1981). In mammals, maximal rate of oxygen consumption (VOmax) is not limited by any one step of the oxygen cascade; rather limitations to VOmax are distributed across all steps

Bennett, Albert F.

476

Noise-Induced Intermittency in a Convecting Dilute Solution of He3 in Superfluid He4  

Science Journals Connector (OSTI)

Measurements on a convecting dilute He3-superfluid-He4 solution show a transition from periodic to chaotic behavior via intermittency. In a region near but below the onset of intermittency, injection of external noise greater than some threshold value induces chaos.

H. Haucke; R. E. Ecke; Y. Maeno; J. C. Wheatley

1984-11-26T23:59:59.000Z

477

An experimental investigation of convection heat transfer to supercritical carbon dioxide in miniature tubes  

E-Print Network [OSTI]

as an onboard coolant. Highly charged machine elements such as gas turbine blades, supercomputer elements of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China Received 22 December 2001; received on the experimental data, correlations were developed for the axially-averaged Nusselt number of convection heat

Zhao, Tianshou

478

Experimental study of free and mixed convective flow of air in a heated cavity  

SciTech Connect (OSTI)

Free and mixed convection in a strongly-heated rectangular open cavity have been investigated experimentally, to observe the effects of cavity shape and inclination, and of ambient wind, on the velocity and temperature distribution were observed. The long edges of the cavity were horizontal, and parallel to an axis around which the cavity could be rotated. The aperture plane was either vertical (..cap alpha.. = 0/sup 0/), or inclined downward at ..cap alpha.. - 20/sup 0/ or ..cap alpha.. = 45/sup 0/. The height of the aperture, b, was always 0.0947 m, while the depth of the cavity, a, was set so that a/b = 0.5, 1.0, or 1.46. The bottom and back walls were electrically heated - the top wall was indirectly heated by conduction, radiation and convection. The average wall temperature and the ambient temperature were used to define the dimensionless overheat and Grashof numbers. The Prandtl number was that of air. In the studies of mixed convection, the axis of rotation was horizontal and normal to the ambient wind. The Reynolds number was varied from Re = 120 - 1100 to Re = 2000 - 8740. For both free and mixed convection, wall and gas temperature were measured with thermocouples, and shadowgraph pictures were taken. For pure free convection, three time-averaged velocity components, the corresponding normal Reynolds stress components, and one off-diagonal Reynolds stress component were measured with a two-color laser-Doppler velocimeter. A PDP-11/34 minicomputer controlled the sequence of automatic data acquisition, the statistical data reduction and its storage. Statistical results are presented numerically and graphically for two averaging procedures. The principal quantitative result for free convection is that the rate of convective heat loss across the cavity aperture plane is reduced both by increasing a/b and by increasing ..cap alpha... Qualitative observations are recorded and discussed. The most striking observation was the appearance of a periodic oscillation of frequency 2 to 5.5 Hz.

Humphrey, J.A.C.; Sherman, F.S.

1985-04-01T23:59:59.000Z

479

The Chuva Project: How Does Convection Vary across Brazil?  

Science Journals Connector (OSTI)

CHUVA, meaning “rain” in Portuguese, is the acronym for the Cloud Processes of the Main Precipitation Systems in Brazil: A Contribution to Cloud-Resolving Modeling and to the Global Precipitation Measurement (GPM). The CHUVA project has conducted five ...

Luiz A. T. Machado; Maria A. F. Silva Dias; Carlos Morales; Gilberto Fisch; Daniel Vila; Rachel Albrecht; Steven J. Goodman; Alan J. P. Calheiros; Thiago Biscaro; Christian Kummerow; Julia Cohen; David Fitzjarrald; Ernani L. Nascimento; Meiry S. Sakamoto; Christopher Cunningham; Jean-Pierre Chaboureau; Walter A. Petersen; David K. Adams; Luca Baldini; Carlos F. Angelis; Luiz F. Sapucci; Paola Salio; Henrique M. J. Barbosa; Eduardo Landulfo; Rodrigo A. F. Souza; Richard J. Blakeslee; Jeffrey Bailey; Saulo Freitas; Wagner F. A. Lima; Ali Tokay

2014-09-01T23:59:59.000Z

480

Mixed convection and heat management in the Mars gravity biosatellite  

E-Print Network [OSTI]

The Mars Gravity Biosatellite will house fifteen mice in a low Earth orbit satellite spinning about its longitudinal axis. The satellite's payload thermal control system will reject heat through the base of the payload ...

Marsh, Jesse B. (Jesse Benjamin)

2007-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "mesoscale convective systems" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


481

Northern Meltwater Pulses, CO2, and Changes in Atlantic Convection  

Science Journals Connector (OSTI)

...thermohaline circulation system, or “salinity conveyor belt” (10, 11), which is not revealed...researchers estimate where and how fast the conveyor has moved. Today, it appears that a deepwater parcel that forms in the North Atlantic will reach...

Michael Sarnthein

2011-01-14T23:59:59.000Z

482

Growth of Spread in Convection-Allowing and Convection-Parameterizing Ensembles ADAM J. CLARK AND WILLIAM A. GALLUS JR.  

E-Print Network [OSTI]

the 2007 NOAA Hazardous Weather Testbed Spring Experiment, a 10-member 4-km grid-spacing Storm-Scale Ensemble Forecast (SSEF) system was run in real time to provide experimental severe weather forecasting-error metrics for the two SSEF system configurations are compared to similarly configured 20-km grid

Xue, Ming

483

Cloud system resolving model simulations of tropical cloud systems observed during the Tropical  

E-Print Network [OSTI]

the Weather Research and Forecasting (WRF) model. The WRF model is configured with a highest-resolving domain convection. The second regime is a monsoon break, which contains intense localized systems that are rep-based observational systems including a polarimetric weather radar, cloud radar, wind profilers, radi- ation

Jakob, Christian

484

Technical Sessions  

Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

Numerical Simulations of an Idealized ConvE~ctive Numerical Simulations of an Idealized ConvE~ctive System: Comparisons Between Parameteriized and Explicitly Resolved Clouds C.-Y. J. Kao J. E. Bossert Earth and Environmental Sciences Division Los Alamos National Laboratory Los Alamos, NM 87545 Introduction in reproducing the growth and life cyclE~ of a cloud system can then be evaluated. The numeric,al model we have recently acquired from Colorado State University, Regional Atmospheric Modeling System (CSU-RAMS) (Cotton et al. 1988), is used in this research. Since a modified Kuo scheme (Tremback 1990) is built in the RAMS, a by- product of this research is a comparison between two established cumulus parameterizations through the methodology described above. The RAMS MesoscalE~ Model The RAMS mesoscale model is a highl1' flexible modeling

485

Effect of alumina nanoparticles in the fluid on heat transfer in double-pipe heat exchanger system  

Science Journals Connector (OSTI)

This study was performed to investigate the convective heat transfer coefficient of nanofluids made of several alumina ... transformer oil which flow through a double pipe heat exchanger system in the laminar flo...

Byung-Hee Chun; Hyun Uk Kang; Sung Hyun Kim

2008-09-01T23:59:59.000Z

486

Characterization of initiation and growth of selected severe convective storms over Central Europe with MSG-SEVIRI  

Science Journals Connector (OSTI)

The early development of severe convective storms over Central Europe was investigated based on nine cases from the year 2012. Using data from the SEVIRI imaging radiometer aboard the geostationary Meteosat satellite, dynamical and microphysical ...

Fabian Senf; Felix Dietzsch; Anja Hünerbein; Hartwig Deneke

487

Application of a ratiometric laser induced fluorescence (LIF) thermometry for micro-scale temperature measurement for natural convection flows  

E-Print Network [OSTI]

A ratiometric laser induced fluorescence (LIF) thermometry applied to micro-scale temperature measurement for natural convection flows. To eliminate incident light non-uniformity and imperfection of recording device, two fluorescence dyes are used...

Lee, Heon Ju

2004-11-15T23:59:59.000Z

488

The Effect of Heavy Oil Viscosity Reduction by Solvent Dissolution on Natural Convection in the Boundary Layer of VAPEX  

Science Journals Connector (OSTI)

We have studied the effect of viscosity on natural convection in the boundary layer of the vapor extraction (VAPEX) process. VAPEX is a heavy oil recovery method that uses solvents to reduce oil viscosity, and...

Mohammad Javaheri; Jalal Abedi

2013-09-01T23:59:59.000Z

489

An Analytical Model for Determination of the Solvent Convective Dispersion Coefficient in the Vapor Extraction Heavy Oil Recovery Process  

Science Journals Connector (OSTI)

In this article, a new model is developed to determine the solvent convective dispersion coefficient in a solvent vapor extraction (VAPEX) heavy oil recovery process. It is assumed that solvent mass transfer b...

Mohammad Derakhshanfar; Yongan Gu

2012-03-01T23:59:59.000Z

490

List of Publications A Numerical Study of Transient Mixed Convection Flows in a Thermal Storage Tank, J. Solar  

E-Print Network [OSTI]

List of Publications A Numerical Study of Transient Mixed Convection Flows in a Thermal Storage Tank, J. Solar Energy Eng. 105, 246­253 (1983) (with A.M.C. Chan & D. Giusti) An Approximate Analytical

Smereka, Peter

491

Rfrences bibliographiques [1] R. E. Kelly, The onset and development of Rayleigh-Bnard convection in shear flows: a  

E-Print Network [OSTI]

1 Références bibliographiques [1] R. E. Kelly, The onset and development of Rayleigh Publication, London, 1977, pp. 65-79. [2] R. E. Kelly, The onset and development of thermal convection

Paris-Sud XI, Université de

492

Mixed convection and high-pressure low-flow steam cooling data from a 64-rod bundle  

SciTech Connect (OSTI)

Heat transfer data were obtained from low flow steam cooling experiments in a partially uncovered 64-rod bundle. These tests indicated that free convection effects were superimposed on the laminar and turbulent forced convection heat transfer. This paper describes the influence of buoyancy on laminar and turbulent forced convection heat transfer coefficients. Mechanisms due to buoyancy which alter the local heat transfer are summarized. Criteria indicating the importance of buoyancy on laminar and turbulent upflow in a vertical pipe were developed and compared to other criteria found in the literature. These criteria were used to determine the steam cooling data with significant buoyancy influence. Data with buoyancy influence were compared to mixed convection correlations and to a numerical study for rod bundles.

Sozer, A.

1984-01-01T23:59:59.000Z

493

Distribution of Liposomes into Brain and Rat Brain Tumor Models by Convection-Enhanced Delivery Monitored with Magnetic Resonance Imaging  

Science Journals Connector (OSTI)

...Convection-Enhanced Delivery Monitored with Magnetic Resonance Imaging Ryuta Saito...B, T 1-weighted coronal magnetic resonance image of a 9L-2 rat...assistance, Dr. David Newitt (Magnetic Resonance Science Center, University of California...

Ryuta Saito; John R. Bringas; Tracy R. McKnight; Michael F. Wendland; Christoph Mamot; Daryl C. Drummond; Dmitri B. Kirpotin; John W. Park; Mitchel S. Berger; and Krys S. Bankiewicz

2004-04-01T23:59:59.000Z

494

Chaotic flow in a 2D natural convection loop with heat flux boundaries William F. Louisos a,b,  

E-Print Network [OSTI]

- clear reactors, and gas turbine blade cooling among many others [4­6]. The nonlinear dynamics. Examples of natural convection cells occurring in engineering devices include solar water heaters, nu

Danforth, Chris

495

A Synthetic Aperture Radar–Based Climatology of Open-Cell Convection over the Northeast Pacific Ocean  

Science Journals Connector (OSTI)

This paper presents an 8-yr (1999–2006) climatology of the frequency of open-cell convection over the northeastern Pacific Ocean and the thermodynamic and kinematic environment associated with its development. The climatology is based on ...

Todd D. Sikora; George S. Young; Caren M. Fisher; Matthew D. Stepp

2011-03-01T23:59:59.000Z

496

Dependence of Tropospheric Temperature on the Parameterization of Cumulus Convection in the GLAS Model of the General Circulation  

Science Journals Connector (OSTI)

Analysis of the simulation of seasonal change by the GLAS model of the general circulation reveals deficiencies in the simulation of tropospheric temperature and of convective cloud cover. These interrelated deficiencies are due to a spurious ...

H. Mark Helfand

1981-01-01T23:59:59.000Z

497

An Alternative Mass Flux Profile in the Kain–Fritsch Convective Parameterization and Its Effects in Seasonal Precipitation  

Science Journals Connector (OSTI)

The authors have altered the vertical profile of updraft mass flux detrainment in an implementation of the Kain–Fritsch2 (KF2) convective parameterization within the fifth-generation Pennsylvania State University–National Center for Atmospheric ...

Christopher J. Anderson; Raymond W. Arritt; John S. Kain

2007-10-01T23:59:59.000Z

498

Quarterly Journal of the Royal Meteorological Society Q. J. R. Meteorol. Soc. (2013) Phenomenology of Sahelian convection observed in Niamey  

E-Print Network [OSTI]

Quarterly Journal of the Royal Meteorological Society Q. J. R. Meteorol. Soc. (2013) Phenomenology SM. 2013. Phenomenology of Sahelian convection observed in Niamey during the early monsoon. Q. J. R

Guichard, Francoise

499

Numerical study of convection heat transfer during the melting of ice in a porous layer  

SciTech Connect (OSTI)

A numerical study is made of the melting of ice in a rectangular porous cavity heated from above. The Landau transformation is used to immobilize the ice-water interface, and the Darcy-Boussinesq equations are solved by a finite-difference technique. Results are analyzed in terms of the heating temperature and the aspect ratio of the cavity. A comparison is made with the case of melting from below. It was found that melting from above is more effective than melting from below when the heating temperature is between 0 and 8 C: convection arises earlier, the melting process is faster, and the total melt at steady state is thicker. The critical time for onset of convection is minimum when the upper boundary is heated at 6 C. At this heating temperature, one also obtains a maximum heat transfer rate (Nusselt number).

Zhang, X.; Nguyen, T.H. (Ecole Polytechnique de Montreal, Quebec (Canada). Dept. of Mechanical Engineering)

1994-05-01T23:59:59.000Z

500

Numerical investigation of transient flow-mode transition of laminar natural convection in an inclined enclosure  

SciTech Connect (OSTI)

The present work is concerned with a numerical investigation of transient laminar natural convection and the associated flow-mode transition in a two-dimensional rectangular enclosure. Navier-Stokes/Boussinesq equations for fluid flow and energy balance are solved by using the SIMPLE-C algorithm. Air of Pr = 0.71 in a differentially heated enclose of length-to-height aspect ratio As = 4 and at Ra = 5,000 is chosen as the flow model to examine the influences of the inclination. Calculations of time accuracy are performed to investigate the transient procedure of the flow-mode transition with increasing or decreasing inclination. The present results reveal that, at some critical situations, natural convection in inclined enclosures is very sensitive to the change in tilt angle, and the associated heat transfer rates are closely related to the correspondent cellular flow patterns.

Tzeng, P.Y.; Soong, C.Y.; Sheu, T.S. [Chung Cheng Inst. of Tech., Taoyuan (Taiwan, Province of China). Dept. of Aeronautical Engineering

1997-02-07T23:59:59.000Z