If you set the mesh to not renumber nodes and elements before reading the mesh the element numbers will correspond to those from the file (just remember that libmesh is 0 based whole your mesh format might not be)
Derek Sent from my iPhone On May 21, 2013, at 12:09 PM, Robert Blake <[email protected]> wrote: > Do you have any idea on how best to populate that constant monomial field? > > Ideally I'd like that constant monomial field to have the same value > Elem->id() in a serial mesh. This would help when checkpointing said > external data structure in parallel. However, I can't fill in the > constant monomial term until the mesh has been partitioned, and once the > mesh has been partitioned Elem->id() changes. > > This is not a problem for the subdomain_id() route, as I can set those > ids serially then distribute them appropriately in parallel. However > based on my amateur digging in the code base, certain mesh > readers/writers will produce horribly inefficient outputs if > n_subdomains = n_elem. > > On 05/21/2013 01:51 PM, Derek Gaston wrote: >> If you don't want to go the subdomain_id route then I would create an >> explicit system with ONE monomial that has it's value set to a key >> value (ie just store an int per element) then use that to index into >> your datastructure. That value will be prolonged to child elements >> under refinement and work in parallel etc. >> >> A float stores an int just fine. And constant monomial fields just >> retain their values in AMR. >> >> Derek >> >> Sent from my iPhone >> >> On May 21, 2013, at 11:14 AM, Robert Blake <[email protected]> wrote: >> >>> Does anyone have any advice on this question? John, maybe? >>> >>> >>> On 04/30/2013 11:29 AM, Robert Blake wrote: >>>> I am trying to run a FEM simulation wherein every element has a >>>> variable-length C data structure defined in an external non-libmesh file >>>> format. What is the easiest way to get this data into libmesh and use >>>> it in parallel? >>>> >>>> I see only a couple of ways of doing this: >>>> >>>> 1.) I can easily do this using MeshData and foreign_id_for_elem(). This >>>> works serially, but MeshData is deprecated and doesn't work in parallel. >>>> >>>> 2.) I can create my own data structure that indexes off of Elem->id(). >>>> Is this possible? Based on my cursory glance at the code, I fear that >>>> Elem->id() will change after partitioning in parallel. If this happens, >>>> this technique won't work. In addition, I'm not sure how this will work >>>> if I decide to use AMR >>>> >>>> 3.) I can give each mesh a unique subdomain_id(), and create my own data >>>> structure that uses that subdomain_id() as an index. This should work >>>> in parallel and for AMR, but it seems like a horrible abuse of the >>>> subdomain_id() and might cause problems for parts of the code that >>>> assume n_subdomains << n_elems. >>>> >>>> 4.) I can create an ExplicitSystem with a (CONSTANT,MONOMIAL) term, fill >>>> that data with an integer ID, and then use that ID to index into an >>>> external data structure of my choosing. I know that this is now the >>>> preferred way of storing element data, but >>>> a.) It seems like a hack to use a floating point field to store integer >>>> data >>>> b.) I'd have to take extra care to ensure the variable is NOT >>>> interpolated when doing AMR >>>> c.) I'm still not sure how to populate these data values. All the code >>>> I've seen for populating variables for ExplicitSystems uses >>>> FunctionBase<> which takes point data as it's argument. I'm not quite >>>> sure how to easily access an element's data using (x,y,z) coordinates as >>>> an argument. >>>> >>>> Is there something I've missed? Help! >>>> >>>> Rob >>>> >>>> >>> >>> ------------------------------------------------------------------------------ >>> Try New Relic Now & We'll Send You this Cool Shirt >>> New Relic is the only SaaS-based application performance monitoring service >>> that delivers powerful full stack analytics. Optimize and monitor your >>> browser, app, & servers with just a few lines of code. Try New Relic >>> and get this awesome Nerd Life shirt! http://p.sf.net/sfu/newrelic_d2d_may >>> _______________________________________________ >>> Libmesh-users mailing list >>> [email protected] >>> https://lists.sourceforge.net/lists/listinfo/libmesh-users > ------------------------------------------------------------------------------ Try New Relic Now & We'll Send You this Cool Shirt New Relic is the only SaaS-based application performance monitoring service that delivers powerful full stack analytics. Optimize and monitor your browser, app, & servers with just a few lines of code. Try New Relic and get this awesome Nerd Life shirt! http://p.sf.net/sfu/newrelic_d2d_may _______________________________________________ Libmesh-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/libmesh-users
