Sorry, I forgot to note that the oscillations always take place next to the boundary of my parallelized fields (see picture below)! Maybe its an issue due to the parallelization process? There are to many possibilities about the reason of termination, so I hope somebody can give me an advice. Thanks! Best regards Fabian [cid:44c10113-782b-4fb7-a626-997b5dd94cac] (Picture shows the boundary between two parallelized fields and oscillations next to this boundary and the airfoil-surface) ________________________________ Von: nektar-users-bounces@imperial.ac.uk [nektar-users-bounces@imperial.ac.uk]" im Auftrag von "Selbach, Fabian [fabian.selbach@student.uni-siegen.de] Gesendet: Mittwoch, 30. November 2016 14:21 An: nektar-users@imperial.ac.uk Betreff: [Nektar-users] Nonphysical terminated simulation - CompressibleFlowSolver Dear users, I hope you can help one more time. I got nonphysical oscillations during my airfoil-simulation. At that time my simulations terminate with the message: "NaN found during time integration". For more information of the error and parameters see pictures below. I tried to solve this by a higher polynomial degree up to p=7 (this generates 1.5 Mio grid-points here for a 2D simulation), but the simulation terminates still. The time step itself is computed by a fixed CFL=0.9 condition. Maybe this is the wrong way, because this condition is not sufficient? So please can somebody give me a hint about that? Do I have to use another kind of grid, because the resolution of the boundary at the peak of the airfoil is not high enough or the grid lines have no be orthogonal to the surface? I am already using the spherigons-tool and tried to get a smooth boundary of my airfoil. I am using the CompressibleFlowSolver on a parallel run up to 96 CPUs by solving the Euler-Equations (EulerCFE) and the Navier-Stokes-Equations (NavierStokesCFE). The simulation terminates for both. By the way what is the difference between EulerCFE and EulerADCFE (there are no information about it anywhere)? I tried to run the example NACA0012 of the paper "Nektar++: An open-source spectral/hp element framework". The conditions use the EulerADCFE, but by running this example the simulation does not terminate, but also does not change (values of every variable in the whole domain are constant over the time - no changes?). Thanks for any help! Best regards Fabian Visualization of the grid at a polynomial degree of p=2 just before terminating: [cid:71608e01-1455-4c20-abbb-9508cb48f805] With auto-scale: [cid:bba140ce-246a-4689-a539-79ff287727b0] Same solution with scaling by user: [cid:a6bda960-d10e-4f91-a833-2e5537f8758c] Please take into account the scaling above. Error and conditions for example p=2: [cid:0ebd995c-1bae-4c43-9d08-91fe685022bf] [cid:300abb94-0f24-4dde-8cda-f67f326ea4f8] [cid:a43f5fef-3537-4385-a2d9-2f49afbcf006] Visualization of the grid at a polynomial degree of p=7 just before terminating: [cid:4d0f11c2-718a-4f85-860f-e5c90684699e] (a few time steps after that the simulation terminates and the values go against inf...)
