My name is Ismael El Houas and I am an aeronautical engineer student from the UPC (Universitat Politècnica de Catalunya).

Nowadays, I am working on my bachelor's degree final project. For my project, I am working with Nektar++ in order to make a CFD study of a supersonic diamond airfoil, so I am using compressible flow solver. I am considering a symmetrical solution, so I decided to simplify the problem and just study half of the domain. To perform this study, half of the domain, I impose symmetrical boundary conditions on the lower boundary.

However, when I study the whole problem the simulation converges to the solution, but when I study just the half of the domain it does not converge. The reported error says: "vacuum is generated". After different tests, I could not find a solution to fix the problem.

The boundary conditions I am imposing on the lower boundary for symmetrical solution are: Dirichlet = 0 condition in rhov in order to avoid entrance of fluid from this side, and Neuman = 0 for the other variables (rho,rhou and E). After different tests, I could not find a solution to fix the problem.

For this reason, I ask you for some tips in order to be able to find a solution to this problem.

Thank you for your attention and congratulations for your work.

Kind Regards,

Ismael El Houas