Hi Spencer,

Many thanks for the quick answer. I tried first using the modal expansion as suggested with same quadrature order but different mode count for pressure and velocity, but did not to work. The other suggestion regarding the curved elements, however, left me thinking. I am using third order equispaced polynomials to represent the curved edges. To check if that could be the issue I refined the mesh around the leading edge and the oscillation disappeared completely, so it seems that the simulation was simply under-resolved in the leading edge after all. Thanks again for your help, because I had been struggling and increasing resolution everywhere except where it was really needed...

Cheers,
Fer

On 05/10/16 18:49, Sherwin, Spencer J wrote:

Hi Fer,

Probably Douglas might be able to comment on this type of simulation since he has just been completing some runs as part of his PhD which has now been examined and accepted.

I attach a copy of a paper under review which has airfoil situations at Re=1000 at this type of aoa.

My only other comment is that we have seen pressure oscillations when the surface is not curved but I note from your .xml file you do have curved elements. I have not checked how smooth the curved elements you are using. Are there any issues on this side.

Finally it is possible to specify an inf-sup compatible space for the velocity correction scheme. Definitely using a Modified Expansion and possibly/probably for the Lagrange basis. However the velocity and pressure quadrature spaces have to be the same. The way to specify such a basis is using an Expansion definition along the lines of:

<E COMPOSITE=“C[0]” BASISTYPE=“Modified_A,Modified_A" NUMMODES="3,3" POINTSTYPE="GaussLobattoLegendre,GaussLobattoLegendre" NUMPOINTS="6,6" FIELDS="p" />

<E COMPOSITE=“C[0]” BASISTYPE="Modified_A,Modified_A" NUMMODES="5,5" POINTSTYPE="GaussLobattoLegendre,GaussLobattoLegendre" NUMPOINTS="6,6" FIELDS="u,v" />

Cheers,

Spencer.