static void diffusion_term (FttCell * cell, DataDif * data)
{
/* fixme: I need to account for the metric */
gdouble size, sizenext, size_ratio;
gdouble un, unext, unprev;
FttDirection d0;
for (d0 = 0; d0 < FTT_NEIGHBORS; d0++) {
FttCellFace face = gfs_cell_face(cell, d0);
gdouble flux = 0.;
gdouble invdens = data->alpha ? gfs_function_face_value (data->alpha, &face) : 1.;
gdouble visc = gfs_diffusion_cell (data->d->D, cell);
GfsStateVector * s = GFS_STATE (cell);
FttDirection od = FTT_OPPOSITE_DIRECTION(d0);
un = interpolate_value_skew (cell, d0, NULL, data->fd);
if ((d0 % 2) != 0) {
unext = interpolate_value_skew (cell, od , NULL, data->fd);
unprev = interpolate_value_skew (cell, d0 , &(d0) , data->fd);
sizenext = ftt_cell_size (cell);
size = get_size_next (cell, d0);
}
else {
unext = interpolate_value_skew (cell, d0, &(d0), data->fd);
unprev = interpolate_value_skew (cell, od, NULL, data->fd);
size = ftt_cell_size (cell);
sizenext = get_size_next (cell, d0);
}
size_ratio = ( 1. + sizenext / size ) / 2;
flux = ( (unext - un)/sizenext - (un - unprev)/size );
FttComponent c = d0/2;
#if FTT_2D
FttComponent oc = FTT_ORTHOGONAL_COMPONENT (c);
flux += size_ratio * transverse_diffusion(cell, oc, d0, un, data->fd);
#else
static FttComponent orthogonal[FTT_DIMENSION][2] = {
{FTT_Y, FTT_Z}, {FTT_X, FTT_Z}, {FTT_X, FTT_Y}
};
flux += size_ratio * transverse_diffusion(cell, orthogonal[c][0], d0, un, data->fd);
flux += size_ratio * transverse_diffusion(cell, orthogonal[c][1], d0, un, data->fd);
#endif
s->f[d0].v -= invdens*visc*flux;
}
}
static void darcy_coefficients (GfsSourceDarcy * sd, FttCell * cell, GfsVariable ** u, FttComponent c1, gdouble f[2])
{
GfsPorous * por = GFS_POROUS (gfs_object_simulation (sd));
GfsDomain * domain = GFS_DOMAIN(por);
GfsFunction * porosity = por->porosity;
GfsFunction * K = por->K;
gdouble viscosity = 0.001;
GfsVariable ** U = gfs_domain_velocity (domain);
GfsSourceVelocity * sv = GFS_SOURCE_VELOCITY (domain);
GfsSourceDiffusion * d = source_diffusion_viscosity (U[0]);
if (d)
viscosity = gfs_diffusion_cell (d->D, cell);
f[0] = (viscosity * gfs_function_value (porosity,cell))/gfs_function_value (K,cell);
gdouble modu;
modu = fabs(sqrt(GFS_VALUE (cell, sv->v[0])*GFS_VALUE (cell, sv->v[0]) +
GFS_VALUE (cell, sv->v[1])*GFS_VALUE (cell, sv->v[1])));
f[1] = (gfs_function_value (porosity,cell))/sqrt(gfs_function_value (K,cell))*modu;
}