Discussion Forum

Dear All,
I have one seemingly complicated model to deal with. I got struck for more than a month. The model is attached below. The brief introduction is that:
The upper two domains are solid, the lower two domains are also solid and the intermediate domain is fluid. The convective fluid flow occurs in fluid domain, and extract heat from adjacent solid domains. Initially, the upper solid are separate from lower solid (no contact in tips). With loading, they contact physically and contact pressure varies with different temperature difference between solid and fluid.
The most tricky part is two half solid spheres. As it mentioned in solution center, if the contact feature in solid mechanics is involved, the “form assembly” should be selected. (www.comsol.com/support/knowledgebase/1216/). So in the geometry finalization, I chose “form assembly”. Intuitively, the contact pair should be built beforehand at the tip region of half spheres. Other parts of fluid-solid interface are identity pair with continuity properties. Does this consideration is right or not?
But in “form assembly” scope, the fluid-solid interaction node in Multiphysics module are not available in entity section. I don’t understand this point.
For the steps, due to delicate contact problem, I first just execute solid mechanics to make sure tips of half sphere contacted. Then laminar flow module and solid mechanics module are coupled to further the study a little bit. If it succeed, I would add heat transfer module to fully coupled three physics. Does this consideration is reasonable or not?
By the way, the contact on the tips of half spheres are always existent after first attached together.
Any suggestion about this model will be appreciated.
Thanks.