Negative pressure error. Supersonic wing simulation.
Hello. I am trying to model supersonic flow over a wing in Simlab, to later study aerodynamic heating and optimize the wing based on this.
I'll provide some background over the steps I took so far for the simulation.
Import wing tunnel geometry (solid cube with the wing removed)
Perform surface mesh, to later CFD mesh with boundary layer.
Material: Ideal gas
Boundary conditions:
Inlet: 500 m/s (x) 20 m/s (z). 101325 Pa. 273 K.
Outlet: 101325 Pa
Symmetry
Slip for the wind tunnel walls
No slip for the wing wall.
Initial conditions;
Eddy viscosity: 0.0001
Pressure: 101325 Pa
Temperature: 273 K
Velocity: 500 m/s (x) 20 m/s (z)
I attach the log file and the database file just in case it is of any help.
The simulation works fine for Mach 1.1, but as soon as I increase the inlet velocity to Mach 1.5, the solver crashes. In the log file, the error seems to come from a negative pressure arising.
Is something wrong with my boundary/initial conditions? Maybe should I use far-field conditions instead of inlet/outlet? I have performed some attempts at it but seemed to get similar results, but I got to say I do not really understand that BC.
Thanks beforehand. Any help is appreciated.
Answers
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First - you'll need to use the mildly compressible or supersonic solver for this which from the Log file I see you're already doing - as in this tutorial:
https://help.altair.com/hwcfdsolvers/acusolve/topics/tutorials/acu/acu_2400_intro_sl_r.htmThat being said - external supersonic flows are not good applications for AcuSolve. The target and tested applications for the compressible solvers are internal flows (compressors, turbos, etc) - not external. Your experience may vary, since it is really beyond the scope of the solver. You'll need very fine mesh - Y+ on the order of 1 with a growth rate around 1.1 to 1.2, fine resolution in the volume including the wake region, etc., and that particularly as shocks start to form. Maybe smaller time increment, etc.
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