[petsc-users] Plex Submesh

[Matthew Knepley]

On Tue, Apr 30, 2013 at 2:57 AM, Dharmendar Reddy
<dharmareddy84 at gmail.com>wrote:

> Hello,
>          I have a doubt about how the node ordering in plex submesh is
> created.
>
> I create a oneD mesh along y-direction from a two dimensional square mesh
> in x-y direction.  In the original mesh the nodes are indexed such that the
> count increase in y-direction first and then in x-direction.
>
> Consider a 5 by 5 square mesh
>
> Now the oneD subdm  has 5 nodes and 4 cells
>
> if the coordinates of the nodes is [0,1.0,2.0,3.0,4.0]   in x and y
> drection
>
> I see that  cells in the subdm for x=1.0 have support:
> Vertex id here is the numbering with respect to subdm.
>
> cellId:     vertexId       ExpectedVertexId (or atleast i want this also
> this will be the
>                                                                    case
> for x = 0.0)
>
>  0            5    4            4  5
>  1            6    5            5  6
>  2            7    6            6  7
>  3            8    7            7   8
>
>  Of course this is consistent with the node ordering in original dm but i
> i use the coordinates of the nodes i get detJacobain negative.
>
> I am not sure if this make sense ....
>
> Should not (or can ) the nodes in the subdm be reoriented such that they
> all have positive orientation ?
>

I am working all of this out now, which is why I have been slow in
replying. I have a code that uses
this call in every possible way, in all dimensions. I should be done this
week.

You are correct that the orientation is likely off. That is what I am
checking.

  Thanks,

     Matt


> Since i am creating the subdm using indexset of a select points in
> original dm, i can see that the connectivity is preserved.
>
> Should i create a new dm using DMcreatefromCellList after fixing the
> orientations ? but then i need maps from this dm to orignal dm to access
> the dof values.
>
> Thanks
> Reddy
> --
> -----------------------------------------------------
> Dharmendar Reddy Palle
> Graduate Student
> Microelectronics Research center,
> University of Texas at Austin,
> 10100 Burnet Road, Bldg. 160
> MER 2.608F, TX 78758-4445
> e-mail: dharmareddy84 at gmail.com
> Phone: +1-512-350-9082
> United States of America.
> Homepage: https://webspace.utexas.edu/~dpr342
>



-- 
What most experimenters take for granted before they begin their
experiments is infinitely more interesting than any results to which their
experiments lead.
-- Norbert Wiener
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.mcs.anl.gov/pipermail/petsc-users/attachments/20130430/9b42143e/attachment.html>