I have been running simulations of 3D convection in a box with the incompressible Navier-Stokes solver.

I find that there is always an anomaly at one of the points, where the pressure field is zero (it is obvious that this zero value is wrong - see attached image).  It might be worth noting that in the image, there are 12 elements with 4 modes per direction each, so 12*4^3 (=768) degrees of freedom, and the anomalous point seems to be number 767 i.e. the final one, so perhaps the last pressure variable is not being updated.  The session file used to generate the result shown in the image is attached (takes about 1min to run on my laptop).  Also note it is correct that u, v, w, and T are zero at the sample point - just not p!

I have found this issue on a variety of cuboidal and also tetrahedral meshes.

The command to run I used is

mpiexec -np 4 incnavierstokessolver nektar_3d_convection.xml

Can anyone help resolve this?

Many thanks,

Dr Ed Threlfall, UKAEA.