Learning Forum

[mateolanda1]

Hello, I am an undergraduate student and I am fairly familiar with the software (FLUENT). I have been trying to do a supersonic simulation on a cylindrical object with a round nose (missile like) with a cylindrical boundary. I am using periodic symmetry and only using 1/16th of the cylinder. 

Is there a way to set up the problem in a way to have a velocity inlet, two symmetry planes, and two pressure outlets? I am tasked with obtaining the pressure values at the round cylinder wall with non-reflecting conditions, same for the rear outlet face. I have tried and the simulation either diverges or outright stops. The only way I can move forward is to change the cylinder wall to "wall" but that would not allow me to select the non-reflecting conditions.

This is for inviscid supersonic flow at 16 km above ground.

 

[RK]

Hello, 

Why do you need 2 symmetry plane and pressure outlets? 

There could be many reasons for the simulation to diverge. It depends on the mesh, the solver you using and also the boundary conditions. 

Here are a few suggestions: 

First, make sure the mesh quality is good. You can do so be clicking on "Check Quality". I would suggest using the density based approach and for the boundary condition, the pressure inlet and pressure farfield might yield better results. Since, there is no enclosure in the computational domain, I do not see the reason for using the wall boundary condition. In the solution method, AUSM scheme has been used frequently for high supersonic flows. Since, the object is flying at 16 km above sea level, make sure the reference values are calculated accordingly. 

[Rob]

Have you looked at the far field pressure boundary? There will be an aerofoil example at subsonic speeds show it's use.