DA question

[Sean Dettrick]

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
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>              04/09/2008 04:09
>
>
>              PM
>
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>              Please respond to
>              petsc-users at mcs.a
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>
>
>
>  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
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>  Subject
>  >              Available                 Re: DA question
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>  >
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>  >
>
>  >              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
>  >>
>  >
>  >
>  >
>
>
>
>