- [x] Account for extrusion factor (see !914) - [x] fluxes - [x] storage terms - [x] Add 2D friction term to mimic 3D flow (see !925) - [ ] Implement better tests (e.g. 3D, transient, backward-facing step, etc.) (see #415) - [ ] Improve the documentation (help message) and appearance of the test provlems - [x] Improve inheritance structure (especially for RANS models) (see !915) - [x] Improve boundary conditions (#487) - [x] Check caching on/off