Hi Octavio, Thank you for using Nektar++. The issue you are facing is due to the mesh primarily. As you can see in the attached image, your flow gradually builds up energy around the upper- and lower-most points of the circle. At a certain point it will diverge. You need to create a sort of boundary layer mesh despite your problem being inviscid. I also noted that you start from an initial guess but have set the polynomial order to be 1 and 3 in the two composites. This is trying to "jump-start" if you like, you first need to settle the solution and do so gradually. I would recommend starting from a steady solution, that will help. Also, start with a lower time step and then gradually ramp it up. If you switch to the viscous solver then you will also have the added artificial viscosity option. Thanks, Guglielmo ________________________________ From: nektar-users-bounces@imperial.ac.uk <nektar-users-bounces@imperial.ac.uk> on behalf of Octavio Morales <octavioaugustomg@gmail.com> Sent: 26 February 2024 02:11 To: nektar-users <nektar-users@imperial.ac.uk> Subject: [Nektar-users] Issue with compressible flow solver This email from octavioaugustomg@gmail.com originates from outside Imperial. Do not click on links and attachments unless you recognise the sender. If you trust the sender, add them to your safe senders list<https://spam.ic.ac.uk/SpamConsole/Senders.aspx> to disable email stamping for this address. Hi, I am having some trouble with the compressible flow solver when I run the attached case. I am attaching the .xml file and the .out file This is the error I am getting and don't know how to solve it: Warning : Level 0 assertion violation # Nonlinear solver not converge in DoImplicitSolve * Newton-Its converged (RES=-nan Res/(DtRHS): -nan with 10 Non-Its) Steps: 672 Time: 6.72000e-01 CPU Time: 10.604s Fatal : Level 0 assertion violation NaN found during time integration. Fatal : Level 0 assertion violation NaN found during time integration. Fatal : Level 0 assertion violation NaN found during time integration. Fatal : Level 0 assertion violation NaN found during time integration. -------------------------------------------------------------------------- Primary job terminated normally, but 1 process returned a non-zero exit code. Per user-direction, the job has been aborted. -------------------------------------------------------------------------- -------------------------------------------------------------------------- mpirun detected that one or more processes exited with non-zero status, thus causing the job to be terminated. The first process to do so was: Process name: [[52564,1],2] Exit code: 1 -------------------------------------------------------------------------- Any Help or comment will be extremely appreciated. Kind regards, Octavio Morales. U-MOFABI, Facultad de Ingeniería UNAM