Actual source code: adaptcfl.c

      1: #include <petsc/private/tsimpl.h>

      3: static PetscErrorCode TSAdaptChoose_CFL(TSAdapt adapt,TS ts,PetscReal h,PetscInt *next_sc,PetscReal *next_h,PetscBool *accept,PetscReal *wlte,PetscReal *wltea,PetscReal *wlter)
      4: {
      5:   PetscReal       hcfl,cfltimestep,ccfl;
      6:   PetscInt        ncandidates;
      7:   const PetscReal *ccflarray;

      9:   TSGetCFLTime(ts,&cfltimestep);
     10:   TSAdaptCandidatesGet(adapt,&ncandidates,NULL,NULL,&ccflarray,NULL);
     11:   ccfl = (ncandidates > 0) ? ccflarray[0] : 1.0;

     15:   /* Determine whether the step is accepted of rejected */
     16:   *accept = PETSC_TRUE;
     17:   if (h > cfltimestep * ccfl) {
     18:     if (adapt->always_accept) {
     19:       PetscInfo(adapt,"Step length %g with scheme of CFL coefficient %g did not satisfy user-provided CFL constraint %g, proceeding anyway\n",(double)h,(double)ccfl,(double)cfltimestep);
     20:     } else {
     21:       PetscInfo(adapt,"Step length %g with scheme of CFL coefficient %g did not satisfy user-provided CFL constraint %g, step REJECTED\n",(double)h,(double)ccfl,(double)cfltimestep);
     22:       *accept  = PETSC_FALSE;
     23:     }
     24:   }

     26:   /* The optimal new step based purely on CFL constraint for this step. */
     27:   hcfl = adapt->safety * cfltimestep * ccfl;
     28:   if (hcfl < adapt->dt_min) {
     29:     PetscInfo(adapt,"Cannot satisfy CFL constraint %g (with %g safety) at minimum time step %g with method coefficient %g, proceding anyway\n",(double)cfltimestep,(double)adapt->safety,(double)adapt->dt_min,(double)ccfl);
     30:   }

     32:   *next_sc = 0;
     33:   *next_h  = PetscClipInterval(hcfl,adapt->dt_min,adapt->dt_max);
     34:   *wlte    = -1;   /* Weighted local truncation error was not evaluated */
     35:   *wltea   = -1;   /* Weighted absolute local truncation error was not evaluated */
     36:   *wlter   = -1;   /* Weighted relative local truncation error was not evaluated */
     37:   return 0;
     38: }

     40: /*MC
     41:    TSADAPTCFL - CFL adaptive controller for time stepping

     43:    Level: intermediate

     45: .seealso: TS, TSAdapt, TSGetAdapt()
     46: M*/
     47: PETSC_EXTERN PetscErrorCode TSAdaptCreate_CFL(TSAdapt adapt)
     48: {
     49:   adapt->ops->choose = TSAdaptChoose_CFL;
     50:   return 0;
     51: }