cs_time_step_options_t Struct Reference

time step options descriptor More...

#include <cs_time_step.h>

Collaboration diagram for cs_time_step_options_t:

Data Fields
int	iptlro
cs_time_step_type_t	idtvar
double	coumax
double	cflmmx
double	foumax
double	varrdt
double	dtmin
double	dtmax
double	relxst

Detailed Description

time step options descriptor

Members of this time step options descriptor are publicly accessible, to allow for concise syntax.

Field Documentation

cflmmx

double cflmmx

Max. Courant number for the continuity equation in compressible model.

coumax

double coumax

Maximum Courant number (when idtvar is different from CS_TIME_STEP_CONSTANT).

dtmax

double dtmax

Upper limit for the calculated time step when idtvar is different from CS_TIME_STEP_CONSTANT. Take dtmax = max (ld/ud, sqrt(lt/(gdelta rho/rho)), ...).

dtmin

double dtmin

Lower limit for the calculated time step when idtvar is different from CS_TIME_STEP_CONSTANT. Take dtmin = min (ld/ud, sqrt(lt/(gdelta rho/rho)), ...).

foumax

double foumax

Maximum Fourier number (when idtvar is different from CS_TIME_STEP_CONSTANT).

idtvar

cs_time_step_type_t idtvar

Time step type: constant, adaptive, or steady algorithm variants. If the numerical scheme is a second-order in time, only the option CS_TIME_STEP_CONSTANT is allowed.

iptlro

int iptlro

Clip the time step with respect to the buoyant effects
When density gradients and gravity are present, a local thermal time step can be calculated, based on the Brunt-Vaisala frequency. In numerical simulations, it is usually wise for the time step to be lower than this limit, otherwise numerical instabilities may appear.
iptlro indicates whether the time step should be limited to the local thermal time step (=1) or not (=0).
When iptlro=1, the log shows the number of cells where the time step has been clipped due to the thermal criterion, as well as the maximum ratio between the time step and the maximum thermal time step. If idtvar=CS_TIME_STEP_CONSTANT, since the time step is fixed and cannot be clipped, this ratio can be greater than 1. When idtvar > CS_TIME_STEP_CONSTANT, this ratio will be less than 1, except if the constraint dtmin has prevented the code from reaching a sufficiently low value for dt. Useful when density gradients and gravity are present.

relxst

double relxst

Relaxation coefficient for the steady algorithm. relxst = 1 : no relaxation.

varrdt

double varrdt

Maximum allowed relative increase in the calculated time step value between two successive time steps (to ensure stability, any decrease in the time step is immediate and without limit).
Useful when idtvar is different from CS_TIME_STEP_CONSTANT.

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The documentation for this struct was generated from the following files:

• src/base/cs_time_step.h
• src/base/cs_time_step.cpp