I'm reading up on the Finite Element Method (Zienkiewicz's Book), so I understand better what I'm doing in FEniCS and COMSOL. Currently, I'm wondering about this:
- Using FEM to solve fluid flow problems, do I have to re-assemble the entire system in each iteration of the solution process?
I would assume not since re-assembly only needs to be done if the coordinates of the nodes of the elements change. I can see how this is important in structural analysis, however, this is not the case in fluid dynamics (unless you work with moving meshes). So I assume in a common CFD computation it should be safe to only assemble the system of equations once and carry that through the entire solution process?
I'm asking because, if I understand correctly, not reassembling the system in each iteration of the solution should (in my current understanding) significantly reduce the computation time.