Time integration

D 9 June 2009

Time integration methods are implemented for all solvers. It can be defined in BLOCK:TIME_PARAM set of options.

One can specify

method to compute time step by iteration in the cycle
time integration method

End of cycle

For unsteady computations, the end of cycle is triggered when time integration reaches cycle duration.

For steady computations, the end of cycle is triggered by

a residual criterion which can be optionally specified with RESIDUALS=<value> (if not, project criterion is used).
a maximum number of iterations through CYCLE_MAX_IT=<value> parameter

Note that an existing typhon_stop file triggers end of cycle and end of computation. A maximum total number of iterations can be specified through MAX_IT=<value> parameter

Timestep

Three methods are implemented

the time step is specified DTCALC=GIVEN and given with
DT=<value>
A global time step (default) can be computed according to a stability condition: DTCALC=STABILITY_CONDITION. The stabilty condition is given according to the solver
- heat transfer: FOURIER=<value>
- compressible fluid: CFL=<value>. The optional parameter CFLMAX=<value> can be specified in order to automatically increase the CFL number with convergence up to CFLMAX.
A local time step can be computed according the a stability condition as in previous point with DTCALC=LOCAL_STABILITY_CONDITION. Note that this method is not consistent for unsteady problems.