Assume we have a 2D elastic object represented by a mesh Th, we solve for elasticity equations obtaining displacement u, v, as a fespace object Vh(Th, P2). Then we move the mesh Th according to the displacement, to get Th2. Then I can define another Vh object, let’s say, D=dx(u)+dy(v), as the divergence of the displacement. D is defined on mesh Th, how can I map it to a field D2 on mesh Th2? I mean, if X is a vertex in Th, and X becomes vertex X2 in Th2, then I would like to have D2(X2)=D(X).

I think I find a solution myself.

mesh Th2 = movemesh(Th, [x+u, y+v]);

fespace Vh2(Th2, P2);

Vh2 u2, v2;

D2 = D(x-u, y-v);