BurgersUpwind.c File Reference

Contains functions to compute the upwind flux at grid interfaces for the Burgers equations. More...

#include <stdlib.h>
#include <math.h>
#include <basic.h>
#include <arrayfunctions.h>
#include <mathfunctions.h>
#include <physicalmodels/burgers.h>
#include <hypar.h>

Go to the source code of this file.

Functions
int	BurgersUpwind (double *fI, double *fL, double *fR, double *uL, double *uR, double *u, int dir, void *s, double t)

Detailed Description

Contains functions to compute the upwind flux at grid interfaces for the Burgers equations.

Author

John Loffeld

Definition in file BurgersUpwind.c.

Function Documentation

BurgersUpwind()

int BurgersUpwind	(	double *	fI,
		double *	fL,
		double *	fR,
		double *	uL,
		double *	uR,
		double *	u,
		int	dir,
		void *	s,
		double	t
	)

Upwinding scheme for the Burgers equations

Parameters

fI	Computed upwind interface flux
fL	Left-biased reconstructed interface flux
fR	Right-biased reconstructed interface flux
uL	Left-biased reconstructed interface solution
uR	Right-biased reconstructed interface solution
u	Cell-centered solution
dir	Spatial dimension
s	Solver object of type HyPar
t	Current solution time

Definition at line 15 of file BurgersUpwind.c.

{
  HyPar   *solver = (HyPar*)   s;
  Burgers *param  = (Burgers*) solver->physics;
  int     done,v;

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

  int index_outer[ndims], index_inter[ndims], bounds_outer[ndims], bounds_inter[ndims];
  _ArrayCopy1D_(dim,bounds_outer,ndims); bounds_outer[dir] =  1;
  _ArrayCopy1D_(dim,bounds_inter,ndims); bounds_inter[dir] += 1;

  done = 0; _ArraySetValue_(index_outer,ndims,0);
  while (!done) {
    _ArrayCopy1D_(index_outer,index_inter,ndims);
    for (index_inter[dir] = 0; index_inter[dir] < bounds_inter[dir]; index_inter[dir]++) {

      int p; _ArrayIndex1D_(ndims,bounds_inter,index_inter,0,p);
      int indexL[ndims]; _ArrayCopy1D_(index_inter,indexL,ndims); indexL[dir]--;
      int indexR[ndims]; _ArrayCopy1D_(index_inter,indexR,ndims);
      int pL; _ArrayIndex1D_(ndims,dim,indexL,ghosts,pL);
      int pR; _ArrayIndex1D_(ndims,dim,indexR,ghosts,pR);

      for (v = 0; v < nvars; v++) {
        double eigL = u[nvars*pL+v],
               eigR = u[nvars*pR+v];

        if ((eigL > 0) && (eigR > 0)) {
           fI[nvars*p+v] = fL[nvars*p+v];
        } else if ((eigL < 0) && (eigR < 0)) {
           fI[nvars*p+v] = fR[nvars*p+v];
        } else { 
           double alpha = max(absolute(eigL), absolute(eigR));
           fI[nvars*p+v] = 0.5 * (fL[nvars*p+v] + fR[nvars*p+v] - alpha * (uR[nvars*p+v] - uL[nvars*p+v]));
        }
      }

    }
    _ArrayIncrementIndex_(ndims,bounds_outer,index_outer,done);

  }

  return(0);
}