Applying different Direchlet BCs to different nodes on a boundary

Question

I am solving a 3D linear elasticity problem.

On one boundary, I have different [ux, uy, uz] BCs on the different nodes. How to accomplish this in fenics.

It would be of great help if anyone can help.

Sincerely,
Shankha

Answer 1

If you have an analytical expression for the components you can use an a vector expression, i.e.

bc = DirichletBC(V,Expression(("x[0]","x[1]","x[2]")), bnd_func)

Comments

Hi,

Thanks for you response. But this is not the answer to my question.

However I hope I solved it by myself (it would be nice if you can have a look and confirm). This is how I define the list of subdomains

interface = [CompiledSubDomain("x[0] == xi && x[1] == yi && x[2] == zi", xi = pos[0], yi = pos[1], zi = pos[2]) for pos in interface_nodes]

where interface_nodes stores the coordinates of the interface node. This mean each of these interface node is a subdomain by itself.

There I define the Direchlet BC for each of the interface nodes as follows:

u0_interface = [Constant(disp) for disp in interface_node_disp]
bc_interface = [DirichletBC(V, u0_interface[count] , interface[count]) for count in range(0, np.shape(interface_node_disp)[0])]

where interface_node_disp has the displacements BC values [ux, uy, uz] for each of the interface nodes.

Hope to hear your opinion soon.

Sincerely,
Shankha.