Dear developers of Nektar++, 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
Dear Ismael, I think that the solution is not converging because in the compressible solver the imposition of the boundary condition is done in a weak manner through the flux function and at each boundary point a Riemann problem is solved to find the solution with which the flux is evaluated. The best way to solve this problem is to use a Symmetry User Defined boundary condition. In this way the Riemann solver will find the right solution on the boundary that corresponds to the symmetric problem you are trying to solve. I hope that this can help. Kind regards, Daniele
Il giorno 22 apr 2017, alle ore 12:13, Ismael El Houas Ghouddana <ismael.elhouas@gmail.com> ha scritto:
Dear developers of Nektar++,
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 _______________________________________________ Nektar-users mailing list Nektar-users@imperial.ac.uk https://mailman.ic.ac.uk/mailman/listinfo/nektar-users
participants (2)
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De Grazia, Daniele
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Ismael El Houas Ghouddana