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 > >> > > > > > > > > > >
