For divergence calculation I recommend avoid using UDSS to get gradient of gradients. It is better to rely on Finite Volume Way to get gradients and to have then Laplacian. The code is bit tricky but very complex.

@DrAmine, Could you guide me on how to do that?nWith @YasserSelima, 's help, I was able to calculate and store the unit vector n̂. Now I just need to handle the term ∇⋅n̂, which is the divergence of the vector. Please suggest.n