[CIG-SHORT] Dirichlet and Neumann boundary conditions simultaneously for different degrees of freedom of the same edge

[Brad Aagaard]

On 1/24/17 10:04 AM, Ekaterina Yevgenyevna Bolotskaya wrote:
> Dear Developers,
>
> I've started working with pylith only recently.
>
> I'm currently working on a 2D simulation where I need to initially
> compress a 2D block in both directions and then have y-displacement
> fixed for vertical boundaries. Thus, I need to apply Dirichlet and
> Neumann boundary conditions simultaneously for different degrees of
> freedom of the same edge.
>
> Could you tell me if I can do that and how?

Yes, you can apply Dirichlet BC to the tangential DOF and a Neumann BC 
with normal tractions. If you constrain the tangential DOF with a 
DirichletBC than the shear traction in a Neumann BC has no effect, so it 
os best to just have it zero in the spatial database for the boundary 
tractions. Just create an array of BC for each one. For example

bc = [xpos_disp, xpos_traction, ...]
bc.xpos_disp = pylith.bc.DirichletBoundary
bc.xpos_traction = pylith.bc.Neumann

Then set the parameters for each boundary condition as usual.

Regards,
Brad