Learning Forum

[ae22b001]

Hello, Im trying to simulate a supersonic isolator. I have attached a picture of my mesh.

The inlet conditions - Pressure inlet - total pressure = 207kpa, gauge pressure is 42kpa total temp = 310 k

outlet - pressure outlet - gauge pressure = 1pa

density based solver, k-w sst 

However, I'm no matter what I do, I'm not able to get a good steady solution.

Any advice on how to solve this problem?

[Essence]

Hello,

By looking at the mesh, I am assuming the aspect ratio is well in the limits. Could you please share the screenshots of the k-w SST panel, Methods and Controls panel? 

[ae22b001]

 

Hello, I've attached all of it. I've also added mesh metrics of the aspect ratio.

 

 

[Essence]

Hello,

Select High Order Term Relaxation in Methods. Reduce the Courant number to 2.75 for initial iterations. Reduce the URFs to 0.5 (k and omega). Disable the Compressibility effects in k-w SST and try running. Also, let me know the net mass flow rate, net heat transfer rate and apply a variable report definition to judge the convergence. Use Green-Gauss node based gradient.

[ae22b001]

Hello i tried all the suggestions you had mentioned. I set the courant number to 2.75 for about 1000 iterations and then changed it back to 5. I selected higher order term relaxations, disabled compressibility effects in k-w sst, reduced urfs, used green gauss node based gradient. The walls are adiabatic so heat flow was 0. But I'm still no where near convergence. I also used outlet pressure as a monitor . Pls help, thanks. 

[RK]

 

 

Hello, 

You can refer to this tutorial: Chapter 7: Modeling Transient Compressible Flow (ansys.com)

You can use high speed numerics ( see the user's guide for more info) to get a stable solution. The Mach number associated with pressure values can also be run using the pressure based solver. I suggest trying wth PBNS.