Gravity_accelOneBlock(integer, intent(in) :: blockID, integer, intent(in) :: ngcellcomp real(:,:,:,:)),intent(out) :: gvec, integer, intent(in),optional :: potentialIndex)
Compute components of the zone-averaged gravitational acceleration for this block. Include ngcell layers outside block interior. This routine computes the gravitational acceleration for zones in a given block. First-order finite-volume differencing is used everywhere. It is assumed here that the requisite number of guard cells have peen appropriately filled for the variable containting the gravitational potential. Dean Townsley 2008 Contributed to Flash Center at the University of Chicago 2008
blockID - The local identifier of the block to work on gvec(:,:,:,:) - Array to receive gravitational acceleration as as NDIM-dimensional vector. It is assumed the the space provided is the size of the block plus all guard cells. The fist index is the vector component and the latter are cell indices. ngcellcomp - Number of layers outside of block interior to compute gravity potentialIndex - if specified, Variable # to take as potential. Default is GPOT_VAR for the potential stored in the gpot slot of unk, which should correspond to the potential at the current timestep.