[petsc-users] Plex Submesh

[Dharmendar Reddy]

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 ?

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
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