Nonequilibrium flows with smooth particle applied mechanics

Kum, Oyeon

doi:10.2172/105054

Title: Nonequilibrium flows with smooth particle applied mechanics

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Abstract

Smooth particle methods are relatively new methods for simulating solid and fluid flows through they have a 20-year history of solving complex hydrodynamic problems in astrophysics, such as colliding planets and stars, for which correct answers are unknown. The results presented in this thesis evaluate the adaptability or fitness of the method for typical hydrocode production problems. For finite hydrodynamic systems, boundary conditions are important. A reflective boundary condition with image particles is a good way to prevent a density anomaly at the boundary and to keep the fluxes continuous there. Boundary values of temperature and velocity can be separately controlled. The gradient algorithm, based on differentiating the smooth particle expression for (uρ) and (Tρ), does not show numerical instabilities for the stress tensor and heat flux vector quantities which require second derivatives in space when Fourier`s heat-flow law and Newton`s viscous force law are used. Smooth particle methods show an interesting parallel linking to them to molecular dynamics. For the inviscid Euler equation, with an isentropic ideal gas equation of state, the smooth particle algorithm generates trajectories isomorphic to those generated by molecular dynamics. The shear moduli were evaluated based on molecular dynamics calculations for the three weighting functions,more »« less

Authors:

Kum, Oyeon ^[1]

Univ. of California, Davis, CA (United States)

Publication Date:: Sat Jul 01 00:00:00 EDT 1995

Research Org.:: Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

Sponsoring Org.:: USDOE

OSTI Identifier:: 105054

Report Number(s):: UCRL-LR-121751
ON: DE95017266; TRN: 95:006897

DOE Contract Number:: W-7405-ENG-48

Resource Type:: Thesis/Dissertation

Resource Relation:: Other Information: DN: Thesis submitted by Oyeon Kum to University of California, Davis; TH: Thesis (Ph.D.); PBD: Jul 1995

Country of Publication:: United States

Language:: English

Subject:: 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; MATTER; FLUID MECHANICS; SHOCK WAVES; ALGORITHMS; INSTABILITY; TURBULENCE; HYDRODYNAMICS; VISCOSITY; MATHEMATICAL MODELS; CLASSICAL MECHANICS

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                    Kum, Oyeon. Nonequilibrium flows with smooth particle applied mechanics.  United States: N. p., 1995. 
        Web.  doi:10.2172/105054.

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                    Kum, Oyeon. Nonequilibrium flows with smooth particle applied mechanics.  United States.  https://doi.org/10.2172/105054

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                    Kum, Oyeon. 1995.  
        "Nonequilibrium flows with smooth particle applied mechanics".  United States.  https://doi.org/10.2172/105054.  https://www.osti.gov/servlets/purl/105054.

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@article{osti_105054,

  title        = {Nonequilibrium flows with smooth particle applied mechanics},

  author       = {Kum, Oyeon},

  abstractNote = {Smooth particle methods are relatively new methods for simulating solid and fluid flows through they have a 20-year history of solving complex hydrodynamic problems in astrophysics, such as colliding planets and stars, for which correct answers are unknown. The results presented in this thesis evaluate the adaptability or fitness of the method for typical hydrocode production problems. For finite hydrodynamic systems, boundary conditions are important. A reflective boundary condition with image particles is a good way to prevent a density anomaly at the boundary and to keep the fluxes continuous there. Boundary values of temperature and velocity can be separately controlled. The gradient algorithm, based on differentiating the smooth particle expression for (uρ) and (Tρ), does not show numerical instabilities for the stress tensor and heat flux vector quantities which require second derivatives in space when Fourier`s heat-flow law and Newton`s viscous force law are used. Smooth particle methods show an interesting parallel linking to them to molecular dynamics. For the inviscid Euler equation, with an isentropic ideal gas equation of state, the smooth particle algorithm generates trajectories isomorphic to those generated by molecular dynamics. The shear moduli were evaluated based on molecular dynamics calculations for the three weighting functions, B spline, Lucy, and Cusp functions. The accuracy and applicability of the methods were estimated by comparing a set of smooth particle Rayleigh-Benard problems, all in the laminar regime, to corresponding highly-accurate grid-based numerical solutions of continuum equations. Both transient and stationary smooth particle solutions reproduce the grid-based data with velocity errors on the order of 5%. The smooth particle method still provides robust solutions at high Rayleigh number where grid-based methods fails.},

  doi          = {10.2172/105054},

  url          = {https://www.osti.gov/biblio/105054},
  journal      = {},
number       = ,

  volume       = ,

  place        = {United States},

  year         = {Sat Jul 01 00:00:00 EDT 1995},

  month        = {Sat Jul 01 00:00:00 EDT 1995}

}

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Thesis/Dissertation:

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https://doi.org/10.2172/105054

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