Discussion Forum

Hello,

I am modeling diffuse joining using phase field method (entered as coefficient form PDE) in COMSOL. My domain is a parallelogram twice cut across with random surfaces. Each surface is generated as parametric surface - I add some exponentially-distributed noise to a plane. These surfaces are only used to separate domains with different initial conditions - the equation is the same in the whole domain, and boundary conditions only apply on the outer boundaries.

COMSOL easily made the mesh when I was in 2D. Now I need to take my simulation into 3D. COMSOL refuses to build mesh around these random surfaces because of various geometric problems. I artificially suppress noise on the edges of the interface, but the random surfaces still intersect with the outer boundaries.

I tried using virtual geometry - ignore faces and mesh control faces, but then meshing still takes into account the random surface. I wonder whether it's possible to build the mesh only based on the simple geometry of the parallelogram, but still use the random surfaces as separators for initial conditions.

My last resort would be to make initial conditions a piecewise function in 3D, which changes at the points specified by the random function. However, that seems to be too much of a pain.

In the attached file Model 1 corresponds to the 2D case, Model 2 to the 3D case. In 2D, mesh is easily created around the random boundary, but in 3D various problems appear, such as unsupported geometry.