Hello All,

I am stuck at this step for months now.

I am trying to recreate motion of a Purcell swimmer in COMSOL's Fluid Multibody Interaction Module. I tried to follow the reference module of "Mechanism submerged in fluid" and try to implement in my design. I created the motion of purcell swimmer and initially just implemented on MBD to see how its working. It worked well.

Now that I add fluid the model is blowing up having convergence issue (Image attached). I used fully coupled method for the simulation. In the ALE I used Prescribed mesh displacement as fsip1.u_solid and fsip1.v_solid to transfer the solid motion to mesh.

I am guessing the problem could be ALE method is not well suited for large movement. In that case I am going to explore other method like Immersed Boundary method, overset meshing, level set method etc.

What could be the possible remedy?