Dear Davide,
First, I would say that in my opinion, a coupling 1D-3D is risky, because, normally, the effect of the coupling should vanish when the mesh size decreases for order two PDEs. So the main risk is to construct a model which is mesh-size dependent. But anyway, this is not so easy to couple 1D and 3D problems in GetFEM, except with the interpolate transformation techniques (see http://getfem.org/userdoc/gasm_high.html#interpolate-transformations). In that case, you should define a 1D mesh and a 3D mesh, use the identity interpolate transformation and you can add some interaction terms between the 1D and the 3D variables in a model, for instance. Best regards, Yves ----- Mail original ----- De: "Davide Manfredo" <manfredo.dav...@gmail.com> À: "getfem-users" <getfem-users@nongnu.org> Envoyé: Mercredi 2 Octobre 2019 11:05:32 Objet: [Getfem-users] Problem interface embedded domain Dear GetFem++ users, I am trying to solve a system concerning blood flow in a tissue and a blood vessel, so I have a coupled 3D (tissue)-1D(vessel) problem, using Matlab interface. My unknowns are velocity u and pressure p either in the tissue and in the vessel, we will call them ut, pt, uv, pv. The first one is a 3D vector field, while the other three are scalar fields. Clearly they are defined on different functional spaces, and so their test functions. I managed to obtain some of the sub-matrices contained in the complete tangent matrix, but when I have to evaluate the interpolation matrix on the boundary of the vessel I find myself stuck. In particular I need to evaluate the interpolation matrix on the boundary of the vessel, that is composed by the surrounding points of each node of the vessel. Now my questions are: 1) How can i define a 1D region in a 3D domain as a set of points and not of convexes nor faces? 2) Since my vessel is a 1D line, how can I define for each node the "ring" of the surrounding points that will be useful to define my interpolation matrix? OmegaM; %mesh Pts; %List of pts that compose the vessel s1 = gf_slice('points', OmegaM, Pts'); CVids1 = gf_slice_get(s1, 'cvs'); CVFIDs = gf_mesh_get(OmegaM, 'outer faces', CVids1); %faces gf_mesh_set(OmegaM, 'region', 33, CVFIDs); %"boundary pipe" around the vessel. Thank you very much for your attention, Best regards, Davide edited <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail> Mail priva di virus. www.avast.com <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2>
