PetscIFunctionImpl.cpp File Reference

Compute the right-hand-side for implicit time integration. More...

#include <stdlib.h>
#include <basic.h>
#include <arrayfunctions.h>
#include <mpivars_cpp.h>
#include <simulation_object.h>
#include <petscinterface.h>

Go to the source code of this file.

Macros
#define	__FUNCT__   "PetscIFunctionImpl"

Functions
PetscErrorCode	PetscIFunctionImpl (TS ts, PetscReal t, Vec Y, Vec Ydot, Vec F, void *ctxt)

Detailed Description

Compute the right-hand-side for implicit time integration.

Author

Debojyoti Ghosh

Definition in file PetscIFunctionImpl.cpp.

Macro Definition Documentation

#define __FUNCT__   "PetscIFunctionImpl"

Definition at line 16 of file PetscIFunctionImpl.cpp.

Function Documentation

PetscErrorCode PetscIFunctionImpl	(	TS	ts,
		PetscReal	t,
		Vec	Y,
		Vec	Ydot,
		Vec	F,
		void *	ctxt
	)

Compute the left-hand-side for the implicit time integration of the governing equations: The spatially discretized ODE can be expressed as

\begin{equation} \frac {d{\bf U}} {dt} = {\bf F}\left({\bf U}\right). \end{equation}

This function computes \(\dot{\bf U} - {\bf F}\left({\bf U}\right)\), given \({\bf U},\dot{\bf U}\).

See Also

TSSetIFunction (https://petsc.org/release/docs/manualpages/TS/TSSetIFunction.html)

Note:

• \({\bf U}\) is Y in the code.
• See https://petsc.org/release/docs/manualpages/TS/index.html for documentation on PETSc's time integrators.
• All functions and variables whose names start with Vec, Mat, PC, KSP, SNES, and TS are defined by PETSc. Refer to the PETSc documentation (https://petsc.org/release/docs/). Usually, googling with the function or variable name yields the specific doc page dealing with that function/variable.

Parameters

ts	Time integration object
t	Current simulation time
Y	State vector (input)
Ydot	Time derivative of the state vector (input)
F	The computed right-hand-side vector
ctxt	Object of type PETScContext

Definition at line 37 of file PetscIFunctionImpl.cpp.

{
  PETScContext* context = (PETScContext*) ctxt;
  SimulationObject* sim = (SimulationObject*) context->simobj;
  int nsims = context->nsims;

  PetscFunctionBegin;
  for (int ns = 0; ns < nsims; ns++) {

    HyPar* solver = &(sim[ns].solver);
    MPIVariables* mpi = &(sim[ns].mpi);
  
    solver->count_RHSFunction++;
  
    int size = solver->npoints_local_wghosts;
    double* u = solver->u;
    double* rhs = solver->rhs;
  
    /* copy solution from PETSc vector */
    TransferVecFromPETSc(u,Y,context,ns,context->offsets[ns]);
    /* apply boundary conditions and exchange data over MPI interfaces */
    solver->ApplyBoundaryConditions(solver,mpi,u,NULL,t);
    MPIExchangeBoundariesnD(  solver->ndims,
                              solver->nvars,
                              solver->dim_local,
                              solver->ghosts,
                              mpi,
                              u );
  
    /* Evaluate hyperbolic, parabolic and source terms  and the RHS */
    solver->HyperbolicFunction(solver->hyp,u,solver,mpi,t,1,solver->FFunction,solver->Upwind);
    solver->ParabolicFunction (solver->par,u,solver,mpi,t);
    solver->SourceFunction    (solver->source,u,solver,mpi,t);
  
    _ArraySetValue_(rhs,size*solver->nvars,0.0);
    _ArrayAXPY_(solver->hyp   ,-1.0,rhs,size*solver->nvars);
    _ArrayAXPY_(solver->par   , 1.0,rhs,size*solver->nvars);
    _ArrayAXPY_(solver->source, 1.0,rhs,size*solver->nvars);
  
    /* save a copy of the solution and RHS for use in IJacobian */
    _ArrayCopy1D_(u  ,solver->uref  ,(size*solver->nvars));
    _ArrayCopy1D_(rhs,solver->rhsref,(size*solver->nvars));
  
    /* Transfer RHS to PETSc vector */
    TransferVecToPETSc(rhs,F,context,ns,context->offsets[ns]);

  }

  /* LHS = Ydot - F(u) */
  VecAYPX(F,-1.0,Ydot);

  PetscFunctionReturn(0);
}