chaos-polymtl / lethe

Repository for the open-source lethe CFD/DEM/CFD-DEM project

https://chaos-polymtl.github.io/lethe/index.html

GNU Lesser General Public License v2.1

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Add missing VOF term in the strong form of the residual #1149

Closed blaisb closed 1 month ago

blaisb commented 1 month ago

Description of the problem

There was a missing term in the strong form of the residual which is (mu_1 - mu_0) (grad_u + grad_u^T) grad_phase
This does not have significant consequences, but I think it is best to remain consistent

Description of the solution

Add missing term

How Has This Been Tested?

All test results barely change, but I had to update them nonetheless
It seems to help a little bit in terms of velocity divergence, but really not much to be honest.

blaisb commented 1 month ago

Nothing to say, everything is clean, but I'd like this question answered before merging : Why don't we add the term also in the strong jacobian ?

Good question. The strong Jacobian term is very expensive to calculate since it has the full hessian. I checked many cases and it never really affects convergence, so for now we can neglect it i think.