[Yuby]

In FVM, the surface normal velocity gradient is used when discretizing the diffusion term.

According to Dr. Jasak thesis (setion 3.3.1.3) the gradient of the face normal is decomposed into orthogonal and non-orthogonal components.

While the orthogonal component is assessed implicitly, the non-orthogonal counterpart is explicitly evaluated as a source term, leveraging the known velocity field.

I'm curious about why the non-orthogonal aspect isn't handled implicitly. Are there any advantages to its explicit implementation?

Thank you so much for your time!