Discussion Forum

Does anyone have any suggestions? It appears as though the normal d() operator is not defined on edges, and the dtang() operator seems to give more sensical answers evaluated on the boundary rather than on the edge itself.

I'm attempting to model a Coefficient Form Boundary PDE on the surface of a 3D model. I would like to impose periodic boundary conditions on the two edges of the boundary; however, it does not appear that COMSOL supports periodic boundary conditions for Boundary PDE's by default. I have attempted to fix this by creating a linear extrusion from edge #1 to edge #2, and then setting Dirichlet boundary conditions on edge #2 equal to the value at edge #1, but this only sets the values, and not the derivatives, equal to each other. I don't see any clear way to set the derivatives equal to each other - attempting a similar approach with a flux/source boundary condition at edge #2 with dtang won't work, as the value on the edge consistently evaluates to some value on the order of 10^-13. Is there any way to do this, or a simpler way in general to impose periodic boundary conditions on coefficient form boundary PDEs?