1 #include <petsc/private/tsimpl.h> /*I "petscts.h" I*/ 2 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 PetscErrorCode ierr; 6 PetscReal hcfl,cfltimestep,ccfl; 7 PetscInt ncandidates; 8 const PetscReal *ccflarray; 9 10 PetscFunctionBegin; 11 ierr = TSGetCFLTime(ts,&cfltimestep);CHKERRQ(ierr); 12 ierr = TSAdaptCandidatesGet(adapt,&ncandidates,NULL,NULL,&ccflarray,NULL);CHKERRQ(ierr); 13 ccfl = (ncandidates > 0) ? ccflarray[0] : 1.0; 14 15 if (!adapt->always_accept) SETERRQ(PetscObjectComm((PetscObject)adapt),PETSC_ERR_SUP,"Step rejection not implemented. The CFL implementation is incomplete/unusable"); 16 17 /* Determine whether the step is accepted of rejected */ 18 *accept = PETSC_TRUE; 19 if (h > cfltimestep * ccfl) { 20 if (adapt->always_accept) { 21 ierr = PetscInfo3(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);CHKERRQ(ierr); 22 } else { 23 ierr = PetscInfo3(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);CHKERRQ(ierr); 24 *accept = PETSC_FALSE; 25 } 26 } 27 28 /* The optimal new step based purely on CFL constraint for this step. */ 29 hcfl = adapt->safety * cfltimestep * ccfl; 30 if (hcfl < adapt->dt_min) { 31 ierr = PetscInfo4(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);CHKERRQ(ierr); 32 } 33 34 *next_sc = 0; 35 *next_h = PetscClipInterval(hcfl,adapt->dt_min,adapt->dt_max); 36 *wlte = -1; /* Weighted local truncation error was not evaluated */ 37 *wltea = -1; /* Weighted absolute local truncation error was not evaluated */ 38 *wlter = -1; /* Weighted relative local truncation error was not evaluated */ 39 PetscFunctionReturn(0); 40 } 41 42 /*MC 43 TSADAPTCFL - CFL adaptive controller for time stepping 44 45 Level: intermediate 46 47 .seealso: TS, TSAdapt, TSGetAdapt() 48 M*/ 49 PETSC_EXTERN PetscErrorCode TSAdaptCreate_CFL(TSAdapt adapt) 50 { 51 PetscFunctionBegin; 52 adapt->ops->choose = TSAdaptChoose_CFL; 53 PetscFunctionReturn(0); 54 } 55