Fluid structure interaction (FSI) for non-boundary-fitted mesh

1

Hi all, I am trying to implement mIFEM(modified immersed finite element method) in FEniCS. Basically, I want to solve an FSI problem using a background Eulerian mesh for the fluid and a separate Lagrangian mesh for the solid. The solid mesh is allowed to deform freely. In mIFEM, the portion of the fluid domain that coincides with the “moving” solid mesh at any time instant is called the artificial fluid. I want to basically divide the fixed fluid mesh in the background into the “artificial fluid” region and “real fluid” region.

Is there a class or a function in FEniCS that can help me keep track of the portion of the fluid mesh that coincides with the overlapping (moving) solid mesh? I have been looking at using the SubDomain class in FEniCS to achieve that but unfortunately, I have not found a way to update the SubDomain based on the position of the overlapping solid domain.
I would be glad if anyone could point me in the right direction. Thanks

1 Like
2

Hi @ic_banner, U do not really need to demarkate the artifical fluid using the overlapping(moving) mesh. Instead u can get away by defining a Lagrange multiplier on the solid mesh and interpolate it to the fluid mesh. THis will give you the smeared force(source term) for the fluid equation, which should be enough to account for the artifical fluid.

Here is an IB-FSI code that does that in FEniCS. (GitHub - patelte8/vanDANA: Immersed boundary - Fluid Structure Interaction solver with heat transfer)