I’m implementing a DG scheme for a Poiseuille flow in Freefem. While I get very satisfying results on the velocity, I’m surprised with negative values for the pressure. Anyone had a similar issue ?

Thank you sir for the reply, it makes perfect sense.

Any idea how to retrieve the ‘physically acceptable’ values ? I tried adding a penalization term of the form intalledges of alpha*jump(p)*jump(q), but no success…

Is your problem an incompressible NS equation? then the pressure is the hydrodynamic pressure and it could be negative (it is only the relative pressure to a constant), and I think you could just add any constant to make sense