Von Neumann stability of the WONDY wavecode for thermodynamic equations of state
Abstract
Previous analyses of the von Neumann stability of the WONDY wavecode (based on the von Neumann--Richtmyer artificial viscosity method) assumed a mechanical stress--strain relation; i.e., they assumed the stress, p, to depend only on the mass density, rho. In a thermodynamic equation of state p is allowed to depend also on the specific entropy, S (or on the specific internal energy, epsilon). If p does not depend on epsilon (or S), then the Grueneisen parameter, GAMMA, is zero. Herein a von Neumann stability analysis of WONDY is done for the more general case when GAMMA is not equal to 0. The result of this analysis is the requirement that the timestep be less than the product of the material increment and a certain function f of the acoustic impedance (a); artificial viscosity coefficient, ..lambda..; and GAMMA. In a region of compression, if ..lambda.. GAMMA is greater than 0, then f(a,..lambda..,GAMMA) is smaller than f(a,..lambda..,0). Therefore, the more general stability analysis yields the result that the timestep restriction now in WONDY may be insufficient for stability in certain regions of certain calculations.
- Authors:
- Publication Date:
- Research Org.:
- Sandia Labs., Albuquerque, NM (USA)
- OSTI Identifier:
- 5299156
- Report Number(s):
- SAND-77-0934
- DOE Contract Number:
- EY-76-C-04-0789
- Resource Type:
- Technical Report
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; COMPUTER CODES; W CODES; HYDRODYNAMICS; ENERGY; ENTROPY; EQUATIONS OF STATE; ONE-DIMENSIONAL CALCULATIONS; RELIABILITY; SHOCK WAVES; STABILITY; STRESSES; THERMODYNAMICS; EQUATIONS; FLUID MECHANICS; MECHANICS; PHYSICAL PROPERTIES; THERMODYNAMIC PROPERTIES; 640410* - Fluid Physics- General Fluid Dynamics
Citation Formats
Hicks, D.L. Von Neumann stability of the WONDY wavecode for thermodynamic equations of state. United States: N. p., 1977.
Web. doi:10.2172/5299156.
Hicks, D.L. Von Neumann stability of the WONDY wavecode for thermodynamic equations of state. United States. doi:10.2172/5299156.
Hicks, D.L. Tue .
"Von Neumann stability of the WONDY wavecode for thermodynamic equations of state". United States.
doi:10.2172/5299156. https://www.osti.gov/servlets/purl/5299156.
@article{osti_5299156,
title = {Von Neumann stability of the WONDY wavecode for thermodynamic equations of state},
author = {Hicks, D.L.},
abstractNote = {Previous analyses of the von Neumann stability of the WONDY wavecode (based on the von Neumann--Richtmyer artificial viscosity method) assumed a mechanical stress--strain relation; i.e., they assumed the stress, p, to depend only on the mass density, rho. In a thermodynamic equation of state p is allowed to depend also on the specific entropy, S (or on the specific internal energy, epsilon). If p does not depend on epsilon (or S), then the Grueneisen parameter, GAMMA, is zero. Herein a von Neumann stability analysis of WONDY is done for the more general case when GAMMA is not equal to 0. The result of this analysis is the requirement that the timestep be less than the product of the material increment and a certain function f of the acoustic impedance (a); artificial viscosity coefficient, ..lambda..; and GAMMA. In a region of compression, if ..lambda.. GAMMA is greater than 0, then f(a,..lambda..,GAMMA) is smaller than f(a,..lambda..,0). Therefore, the more general stability analysis yields the result that the timestep restriction now in WONDY may be insufficient for stability in certain regions of certain calculations.},
doi = {10.2172/5299156},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Nov 01 00:00:00 EST 1977},
month = {Tue Nov 01 00:00:00 EST 1977}
}
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Computational stability of the Von Neumann--Richtmyer method for the case of the ideal gas law
Two stability concepts are of interest for partial difference equations--one arises in theory--the other in practice. The theoretical kind, referred to here as asymptotic stability, is essentially just asymptotic (as ..delta..t, ..delta..x ..-->.. 0) boundedness of the discrete solution. The other kind, referred to here as computational stability, is stability for a fixed ..delta..t and ..delta..x--computational instability is indicated in practice by oscillatory behavior of the discrete approximation--in particular, oscillations of period 2..delta..x. This report is concerned with computational stability. Only approximate stability analyses of the von Neumann-Richtmyer scheme have been done for the case of the ideal gas law.more »