[MOAB-dev] Edges at the ends of a periodic mesh?

[Robert Jacob]

This was motivated by a more practical question.  If there are N cells 
in the j-direction, there will be N+1 edges but the last is the same as 
the first.  So in the call to box create, do we specify N vertices in 
the j-direction or N+1?  I'm still not sure.

Rob


On 5/23/12 10:26 PM, Timothy J. Tautges wrote:
> Yes.  But, in parallel, each piece of mesh looks like a serial mesh, so locally it won't appear periodic (the right hand edge will be distinct from the left hand edge).  Logically across processors, though, the right edge on the rightmost processor will be the same as the left edge on the leftmost processor.  If you write the mesh to a single file, there will be a common edge between the rightmost and leftmost quad.
>
> - tim
>
> ----- Original Message -----
> From: "Robert Jacob"<jacob at mcs.anl.gov>
> To: "Timothy J. Tautges"<tautges at mcs.anl.gov>
> Cc: "Iulian Grindeanu"<iulian at mcs.anl.gov>, moab-dev at mcs.anl.gov
> Sent: Wednesday, May 23, 2012 9:13:20 PM
> Subject: Re: [MOAB-dev] Edges at the ends of a periodic mesh?
>
>
>
> On 5/23/12 9:01 PM, Timothy J. Tautges wrote:
>> Be careful about the parallel case though, where on each proc sharing the edge the edge is represented.
>
> So in the parallel case the edge WOULD be represented on both sides if
> there are multiple processors in the j direction?
>
> Rob
>
>>
>> Also, if you're just trying to create all the edges in one big batch, just put all the quads in a range, then call get_adjacencies, with the last argument Interface::UNION, and that should create/return all of them.
>>
>> - tim
>>
>> ----- Original Message -----
>> From: "Iulian Grindeanu"<iulian at mcs.anl.gov>
>> To: "Robert Jacob"<jacob at mcs.anl.gov>
>> Cc: moab-dev at mcs.anl.gov
>> Sent: Wednesday, May 23, 2012 12:34:12 PM
>> Subject: Re: [MOAB-dev] Edges at the ends of a periodic mesh?
>>
>>
>>
>>
>> ----- Original Message -----
>>
>>
>>
>> Hi,
>>
>> If I have a 2D rectangular mesh which is periodic in one direction, lets
>> say the j direction, then the leftmost and rightmost edge of the mesh
>> are really the same edge. Do they both need to be declared in MOAB? Or
>> does the periodic property mean you only need to describe one of the
>> edges and the other end will know its adjacent to it?
>>
>> Thanks,
>> Rob
>> Hi,
>> I assume that you use ScdInterface;
>> If the box is periodic in j direction, the nodes in that direction will be "periodic".
>> Nodes are not duplicated, the edges that you get on the leftmost and rightmost sides are really pointing to the same nodes, they will not be duplicated, either.
>>
>> How do you get edges after you create quads?
>> You can use "get_adjacency" methods, with "create_if_missing" flag true. Only one edge would be created.
>> The problem is that the order in which these are created is not very "structured"
>> Or do you create them with new scd boxes, of dimension 1, in a loop over i (and then j?)? In that case, you have complete control over "order" they are created in.
>> I hope this helps.
>> Iulian
>>
>>
>> Iulian
>>
>