On Tue, Nov 21, 2017 at 7:10 AM, Tobias Moehle <tobias.moe...@uni-rostock.de > wrote:
> Dear all, > > I have some problem with Lagrange multipliers: Maybe I misinterpret my > results, but somehow they don't have the effect I expected. > > Looking at the solution of systems_of_equations_ex3, (using paraview) I > see the (real part of) pressure r_p to be 0 at time step 0 and than it > jumps to ~10, where it stays for the rest of the simulation. But isn't it > actually enforced to stay at 0 "forever"? > This is beacuse the following lines: // We can set the mean of the pressure by setting Falpha. Typically // a value of zero is chosen, but the value should be arbitrary. navier_stokes_system.rhs->add(navier_stokes_system.rhs->size()-1, 10.); So in this case we set the mean pressure to be 10. We do this just for illustration purposes, to show that the Lagrange multiplier can be used to set the mean pressure to any value you like (but as mentioned in the comment normally one would just set it to zero). If you want to change the value, just change the "10" in the line above. David ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ Libmesh-users mailing list Libmesh-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/libmesh-users
