VlasovComputeCFL.c File Reference

Contains the function to compute maximum CFL over the domain for the Vlasov equations. More...

#include <float.h>
#include <math.h>
#include <basic.h>
#include <arrayfunctions.h>
#include <physicalmodels/vlasov.h>
#include <mpivars.h>
#include <hypar.h>

Go to the source code of this file.

Functions
double	VlasovAdvectionCoeff (int *, int, void *)
double	VlasovComputeCFL (void *s, void *m, double dt, double t)

Detailed Description

Contains the function to compute maximum CFL over the domain for the Vlasov equations.

Author

John Loffeld

Definition in file VlasovComputeCFL.c.

Function Documentation

VlasovAdvectionCoeff()

double VlasovAdvectionCoeff	(	int *	idx,
		int	dir,
		void *	s
	)

Returns the advection coefficient at a given grid index \(c\), where

\begin{equation} c = v_i, \end{equation}

if dir < Vlasov::ndims_x ( \(i = {\rm dir}\)), and

\begin{equation} c = E_i, \end{equation}

the electric field if dir >= Vlasov::ndims_x ( \(i = \) dir-Vlasov::ndims_x).

Note: this function assumes that the electric field has already been set.

Parameters

idx	grid index
dir	Spatial dimension
s	Solver object of type HyPar

Definition at line 28 of file VlasovAdvectionCoeff.c.

{

  HyPar  *solver = (HyPar*)  s;
  Vlasov *param  = (Vlasov*) solver->physics;

  int* dim    = solver->dim_local;
  int  ghosts = solver->ghosts;

  double retval = DBL_MAX;

  if (dir < param->ndims_x) {

    int veldim = dir + param->ndims_x;
    _GetCoordinate_(veldim,idx[veldim],dim,ghosts,solver->x,retval);

  }  else {

    int ndims_x = param->ndims_x;
    int dim_x[ndims_x]; _ArrayCopy1D_(dim, dim_x, ndims_x);

    int idx_x[ndims_x];
    _ArrayCopy1D_(idx, idx_x, ndims_x);
    int p; _ArrayIndex1D_(ndims_x, dim_x, idx_x, ghosts, p);
    retval = param->e_field[ndims_x*p+(dir-ndims_x)];
    
  }

  return retval;

}

VlasovComputeCFL()

double VlasovComputeCFL	(	void *	s,
		void *	m,
		double	dt,
		double	t
	)

Computes the maximum CFL number over the domain. Note that the CFL is computed over the local domain on this processor only.

Parameters

s	Solver object of type HyPar
m	MPI object of type MPIVariables
dt	Time step size for which to compute the CFL
t	Time

Definition at line 19 of file VlasovComputeCFL.c.

{
  HyPar   *solver = (HyPar*)  s;
  Vlasov  *params = (Vlasov*) solver->physics;

  int     ndims  = solver->ndims;
  int     ghosts = solver->ghosts;
  int     *dim   = solver->dim_local;
  double  *u     = solver->u;

  double max_cfl = 0;
  int done = 0; 
  int index[ndims];
  _ArraySetValue_(index,ndims,0);

  while (!done) {

    for (int dir=0; dir<ndims; dir++) {
      double dxinv;
      _GetCoordinate_(dir,index[dir],dim,ghosts,solver->dxinv,dxinv);
      double eig = VlasovAdvectionCoeff(index, dir, solver);
      double local_cfl = eig*dt*dxinv; 
      if (local_cfl > max_cfl) max_cfl = local_cfl;
    }

    _ArrayIncrementIndex_(ndims,dim,index,done);
  }

  return(max_cfl);
}