Please ignore my message. I implemented the fix for grad(phi_i) within my code but that still does not solve my problem.
Best praveen On Wed, Oct 5, 2016 at 10:42 AM, Praveen C <cprav...@gmail.com> wrote: > Dear all > > While a solving a conservation law with DG, I find that total mass is not > conserved. To get total mass conservation, we need > > sum_(i=0,1,...ndofs-1) grad(phi_i(xq, yq, zq)) = 0 > > where phi_i are shape functions and > > ndofs = fe.dofs_per_cell > > and above equation must hold at every quadrature point (xq,yq,zq). > > I have checked in my application that above sum is O(1e-14). While this is > small, it seems to lead to slow mass loss as it gets multiplied by a large > number. > > This can be easily fixed by taking > > grad(phi_0(xq, yq, zq)) = - sum_(i=1,...ndofs-1) grad(phi_i(xq, yq, zq)) > > I want to test if this really solves my conservation problem. > > Can you help me by pointing out in which function I have to put this fix ? > Somewhere in FEValues class ? > > Thanks > praveen > > > -- 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.
