walli 
January 10, 2014 11:21 
Mixing traction/pseudotraction boundary conditions in incompressible flow
I was wondering if there is a way to incorporate the traction boundary conditions in discretizations using the pseudotraction form of the Stokes problem or vice versa. Is there some literature on this or does one simply have no chance? I am mainly interested in finiteelements, but pointers to work dealing with other discretizations or publications dealing with both types of boundary conditions within one simulation would also be helpful.
Stress form of Stokes with pseudotraction b.c.:
Pseudostress form of Stokes with traction b.c.:
I am aware that these boundary conditions are not natural in the respective (weak) formulations, but out of curiosity I would like to know if there are approaches to incorporate these boundary conditions anyway in a stable and convergent manner.
