Two fespce combined computation

hello,everyone, I am writing a code which includes two regions, porous region and solid particle.and each varaible need to computed separately. who can offer me such examples?

  1. it is not possible to define a fespace on 2 meshes.
    but you can add a phantom equation a region with a epsilon to but sur the problem is well defined.
  2. Otherwise you can solve the two problems independantly and make a loop to get the good solution.

if there is an example available?

I have example, but I an no time to explain the example, because the physique if not so simple.

You can try with the coupling of 2 Poissons equations but be careful with Boundary equation.