Re: [Getfem-users] [getfem-users] Build a mesh_fem over an array of meshes

[Yves Renard]

Dear Domenico,

First, your are not obliged to have separate meshes for the different branches, 
I think. You can also define one single global mesh and define some mesh 
regions for each branch and define some mesh_fem on each region.

If you export the three fem fields on a single vtk file, you should retreive 
them but still separated on three different fields.

If you want to export them on a single field and if you define a single global 
mesh, a possibility should be to interpolate the different field on a single 
global non-continuous mesh_fem.

Best regards,

Yves.



----- Original Message -----
From: "Domenico Notaro" <address@hidden>
To: "getfem-users" <address@hidden>
Sent: Tuesday, August 4, 2015 6:32:33 PM
Subject: [Getfem-users] [getfem-users] Build a mesh_fem over an array of        
meshes

Dear Users, 







I have a generic question about the feasibility of the following problem. 


As in previous topics I am dealing with a 1D network immersed in a 3D domain. 
We solve the coupled 1D-3D model in both pressure and velocity. 




Concerning only the 1D network problem , we would like to implement a 
fragmented mesh for velocity in order to deal with compatibility conditions at 
junction points (*). More specifically, we want a unique mesh for pressure in 
the whole network and an array of meshes for velocity in each branch of the 
network. Then we need to build the local matrices (including mixed 
pressure-velocity ones) and to copy them to the monolithic iteration matrix. 
Up to now, I am able to assemble the std::vector<getfem::mesh>. My concerns are 
about defining the finite element methods on multiple meshes. I was thinking to 
implement a std::vector<getfem::mesh_fem> in which each element has been linked 
to one mesh. As an example, I defined a simple constant function over a 
Y-shaped domain: 
f=alpha on Branch 0 
f=beta on Branch 1 
f=gamma on Branch 2 
but when I try to export the values over the three meshes to the same vtk file 
I got only values over the first mesh points (Branch 0). 
Do you think there is a way to handle with this problem? Maybe within the 
context of interpolated fems? 

(*) Since velocity is discontinuous at junctions, we need different dofs for 
velocities over each branch affecting the node in order to impose mass 
conservation 


Best Regards, 
domenico_notaro 

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