From: Joa L. <li...@jo...> - 2009-10-13 15:36:28
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Hi, The problem is that I have to solve my equation on the same domain with very different boundary conditions, making a uniform refinement very inefficient and a waste of time, and worse in my case, RAM. So I do need to start with a very course mesh and refine. cheers Joa On Tue, Oct 13, 2009 at 09:55:54AM -0400, David Knezevic wrote: > If you generate a mesh in gmsh that is sufficiently fine that a mesh > of second order elements captures the geometry well enough, then you > can read that mesh into libMesh, and just use libMesh's adaptive > refinement as in the examples. In that situation, libMesh's adaptive > refinement will interpolate the quadratic boundaries when you refine > the boundary elements... > > But if you want to start with a very coarse mesh, then you might > have to move boundary nodes around etc. I've never had to do that > myself, so perhaps someone else on the list can offer you some > choice advice. > > - Dave > > > Joa Ljungvall wrote: > >Hi, > > > >I'm not sure I understood the answer. I want to start with a very > >course mesh, and refine it based on the solution on the course(r) > >mesh, i.e. adaptive > >refinment. So using gmsh I would have to communicate the solution > >in each step and tell gmsh which regions to refine, or? And if so, > >how? Further more, my domain have some regions where a cylinder it > >cut by a hexagonal, so a quadratic approximation would not do so > >well, would it? > > > > > >cheers > > > > > >Joa > > > >On Tue, Oct 13, 2009 at 09:24:53AM -0400, David Knezevic wrote: > >>I think the simplest thing to do is use second order elements in gmsh. Then > >>when you refine the new nodes will interpolate the quadratic > >>approximation to > >>the boundary of your domain. > >> > >>- Dave > >> > >> > >> > >>Joa Ljungvall wrote: > >>>Hi all, > >>> > >>>I would like to use libmesh to solve a rather simple equation (Laplace/poisson) > >>>but in a domain with a somewhat funny shape of the boundary. To do > >>>this I created a mesh using gmsh, modified example 14 a bit so it > >>>reads my mesh > >>>instead of the l-shaped domain. My problem is that when I refine I get "flat" > >>>surfaces that does not follow my boundary (which is not flat;). How do I go > >>>about and move the new boundary vertices of my tets (I use tets) to the real > >>>boundary? As for the geometry etc. I now how to do it, I`m just not so familiar > >>>with libmesh. > >>> > >>> > >>>kind regards > >>> > >>>Joa Ljungvall > >>> > >>> > >>>------------------------------------------------------------------------------ > >>>Come build with us! The BlackBerry(R) Developer Conference in SF, CA > >>>is the only developer event you need to attend this year. Jumpstart your > >>>developing skills, take BlackBerry mobile applications to market > >>>and stay ahead of the curve. Join us from November 9 - 12, 2009. > >>>Register now! > >>>http://p.sf.net/sfu/devconference > >>>_______________________________________________ > >>>Libmesh-users mailing list > >>>Lib...@li... > >>>https://lists.sourceforge.net/lists/listinfo/libmesh-users |