An efficient discretization for a family of Time Relaxation models

2022 ◽  
Vol 391 ◽  
pp. 114510
Author(s):  
Jeffrey Belding ◽  
Monika Neda ◽  
Rihui Lan
Keyword(s):  
Time Relaxation ◽  
Relaxation Models

scholarly journals Discontinuous Time Relaxation Method for the Time-Dependent Navier-Stokes Equations

2010 ◽  
Vol 2010 ◽  
pp. 1-21 ◽  
Author(s):  
Monika Neda
Keyword(s):  
Stokes Equations ◽  
Relaxation Method ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Time Relaxation ◽  
Optimal Velocity ◽  
Fully Discrete ◽  
Velocity Error ◽  
Approximate Deconvolution ◽  
Relaxation Models

A high-order family of time relaxation models based on approximate deconvolution is considered. A fully discrete scheme using discontinuous finite elements is proposed and analyzed. Optimal velocity error estimates are derived. The dependence of these estimates with respect to the Reynolds number Re is , which is an improvement with respect to the continuous finite element method where the dependence is .

scholarly journals Numerical Study of a Cooling System Using Phase Change of a Refrigerant in a Thermosyphon

Energies ◽  
2021 ◽  
Vol 14 (12) ◽  
pp. 3634
Author(s):  
Grzegorz Czerwiński ◽  
Jerzy Wołoszyn
Keyword(s):  
Mass Transfer ◽  
Phase Change ◽  
Heat Dissipation ◽  
Cooling System ◽  
Numerical Study ◽  
Relaxation Parameter ◽  
Phase Changes ◽  
Transfer Time ◽  
Two Phase ◽  
Time Relaxation

With the increasing trend toward the miniaturization of electronic devices, the issue of heat dissipation becomes essential. The use of phase changes in a two-phase closed thermosyphon (TPCT) enables a significant reduction in the heat generated even at high temperatures. In this paper, we propose a modification of the evaporation–condensation model implemented in ANSYS Fluent. The modification was to manipulate the value of the mass transfer time relaxation parameter for evaporation and condensation. The developed model in the form of a UDF script allowed the introduction of additional source equations, and the obtained solution is compared with the results available in the literature. The variable value of the mass transfer time relaxation parameter during condensation rc depending on the density of the liquid and vapour phase was taken into account in the calculations. However, compared to previous numerical studies, more accurate modelling of the phase change phenomenon of the medium in the thermosyphon was possible by adopting a mass transfer time relaxation parameter during evaporation re = 1. The assumption of ten-fold higher values resulted in overestimated temperature values in all sections of the thermosyphon. Hence, the coefficient re should be selected individually depending on the case under study. A too large value may cause difficulties in obtaining the convergence of solutions, which, in the case of numerical grids with many elements (especially three-dimensional), significantly increases the computation time.

Long time relaxation of resistance in La0.8Sr0.2MnO3 ceramics and La0.65Ca0.35 MnO3 films on ferroelectric substrates

2004 ◽  
Vol 1 (12) ◽  
pp. 3614-3618 ◽  
Author(s):  
Yu.V. Medvedev ◽  
N.I. Mezin ◽  
Yu.M. Nikolaenko ◽  
A.E. Pigur ◽  
N.V. Shishkova ◽  
...  
Keyword(s):  
Time Relaxation ◽  
Long Time

Experimental study of low-temperature long-time relaxation in epoxy resin

1987 ◽  
Vol 68 (3-4) ◽  
pp. 285-299 ◽  
Author(s):  
M. Koláč ◽  
B. S. Neganov ◽  
A. Sahling ◽  
S. Sahling
Keyword(s):  
Experimental Study ◽  
Low Temperature ◽  
Epoxy Resin ◽  
Time Relaxation ◽  
Long Time
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