Daniel, I had went through step-21 and it appears step-43 extends step-21 with the intentions of improving preconditioning et cetera. In essence both the tutorials solve the same set of equations, namely Darcy's Law, conservation of mass and saturation equation. But for this set of approximate model equations the issue of 'spurious currents' doesn't arise (as far as I know). The set of equations I am solving are essentially same in nature to the ones solved in the 'Two phase flow interaction' code gallery program. These are very strong equations to model the two phase phenomenon and require sophisticated numerical treatment. The exact problem I am currently facing in my code is 'spurious currents in the velocity field'. The test case is as follows. The problem is 2D and I am using homogeneous Dirichlet BC throughout the boundary. There is a droplet/bubble at the center of domain. So ideally my velocity vector should be homogeneous throughout the domain for all the time steps. Please have a look at the images of first few time steps - here <https://goo.gl/photos/8ww6erVhk92x4ESF9>. You can see in the images that with increment in time steps a non-physical velocity appears and the solution numerically diverges. This non-physical phenomenon is discussed in the papers I mentioned in the earlier post (just the abstracts are sufficient to know the reasons for 'spurious currents').
You mentioned the 'Two phase flow interaction' code gallery program and it shall be a good starting point for me. I shall then have to learn MPI as it is heavily used in this code. Also the material on XFEM <http://journals.ub.uni-heidelberg.de/index.php/ans/article/view/22317>page shall be helpful. Thank you! -- The deal.II project is located at http://www.dealii.org/ For mailing list/forum options, see https://groups.google.com/d/forum/dealii?hl=en --- You received this message because you are subscribed to the Google Groups "deal.II User Group" group. To unsubscribe from this group and stop receiving emails from it, send an email to dealii+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
