search

libMesh / libmesh

libMesh github repository
http://libmesh.github.io
GNU Lesser General Public License v2.1
657 stars 286 forks source link

Second derivatives for vector variables #2521

Open lindsayad opened 4 years ago

lindsayad commented 4 years ago

I have a LAGRANGE_VEC implementation of the incompressible Navier Stokes equations in MOOSE but when doing SUPG or PSPG stabilization my method is inconsistent because I can't pull in second derivatives (particulary xx, yy, zz for the Laplacian). It would be great to get the second derivatives implemented. This will require some work in TypeNTensor and in the vector FE classes themselves

lindsayad commented 4 years ago

I should clarify and say its inconsistent when doing SUPG or PSPG stabilization and using a second order or higher basis for the velocity variable. In practice if one is using PSPG they're probably using a first order basis. So...really the only time it's an issue is using SUPG and a standard mixed-discretization for velocity and pressure