Amit, I have a staggered grid with H defined along the edges and E as normals across the block faces. So if you have l x m x n blocks, then you need to define your DA as l+1, m+1, n+1, to handle the extra grid point you need for the staggered grid. I use 3 degrees of freedom (for Hx, Hy, and Hz), and all my local calculations just need the box stencil.
Randy Sean Dettrick wrote: > To elaborate on Matt's suggestion, a staggered grid/Yee mesh code > could use a single DA with one degree-of-freedom per component of H > and E. The extra overlap required for staggered guard cells at the > domain boundaries could be dealt with by having a bigger-than-usual > stencil width. For the 2nd order 3D case, this suggests the > DACreate3d routine would have arguments dof=6, s=2, and > stencil_type=DA_STENCIL_STAR. > > It is just a suggestion - I have not tried it. > > Sean > > On Wed, Apr 9, 2008 at 5:06 PM, <Amit.Itagi at seagate.com> wrote: >> Randy, >> >> I guess, since you are doing a frequency domain calculation, you eventually >> end up with a single matrix equation. >> >> I am planning to work in the time domain. Will that change things ? >> >> Thanks >> >> Rgds, >> Amit >> >> >> >> >> Randall Mackie >> <rlmackie862 at gmai >> l.com> To >> >> Sent by: petsc-users at mcs.anl.gov >> owner-petsc-users cc >> @mcs.anl.gov >> No Phone Info Subject >> Available Re: DA question >> >> >> 04/09/2008 04:09 >> >> >> PM >> >> >> Please respond to >> petsc-users at mcs.a >> nl.gov >> >> >> >> >> >> >> Hi Amit, >> >> Why do you need two staggered grids? I do EM finite difference frequency >> domain modeling on a staggered grid using just one DA. Works perfectly >> fine. >> There are some grid points that are not used, but you just set them to zero >> and put a 1 on the diagonal of the coefficient matrix. >> >> >> Randy >> >> >> Amit.Itagi at seagate.com wrote: >> > Hi Berend, >> > >> > A detailed explanation of the finite difference scheme is given here : >> > >> > http://en.wikipedia.org/wiki/Finite-difference_time-domain_method >> > >> > >> > Thanks >> > >> > Rgds, >> > Amit >> > >> > >> > >> > >> >> > Berend van Wachem >> >> > <berend at chalmers. >> >> > se> >> To >> > Sent by: petsc-users at mcs.anl.gov >> >> > owner-petsc-users >> cc >> > @mcs.anl.gov >> >> > No Phone Info >> Subject >> > Available Re: DA question >> >> > >> >> > >> >> > 04/09/2008 02:59 >> >> > PM >> >> > >> >> > >> >> > Please respond to >> >> > petsc-users at mcs.a >> >> > nl.gov >> >> > >> >> > >> >> > >> > >> > >> > >> > Dear Amit, >> > >> > Could you explain how the two grids are attached? >> > I am using multiple DA's for multiple structured grids glued together. >> > I've done the gluing with setting up various IS objects. From the >> > multiple DA's, one global variable vector is formed. Is that what you >> > are looking for? >> > >> > Best regards, >> > >> > Berend. >> > >> > >> > Amit.Itagi at seagate.com wrote: >> >> Hi, >> >> >> >> Is it possible to use DA to perform finite differences on two staggered >> >> regular grids (as in the electromagnetic finite difference time domain >> >> method) ? Surrounding nodes from one grid are used to update the value >> in >> >> the dual grid. In addition, local manipulations need to be done on the >> >> nodal values. >> >> >> >> Thanks >> >> >> >> Rgds, >> >> Amit >> >> >> > >> > >> > >> >> >> >> >
