SimScale CAE Forum

2D Airfoil Simulation on Transonic Regimes

#1

Hello,

I want to make 2D simulation over an airfoil to see transonic regimes. I will use four different mach number (inlet velocity) to achieve this goal. I am using comressible k omega SST tubulance model for it. My problem is to create meshing geometry. I have 3D cad data for the airfoil and tried to make enclosure on this airfoil in order to use in meshing . I do not think I make it right so I started all over and created backgorund mesh box (with 0.02 z value) on the airfoil. But it is still 3D not 2D. How can I make meshing correctly?

1 - https://www.simscale.com/workbench/?pid=5269678674831671143&mi=spec%3A80c94633-d45f-46c1-8b14-2b93bee14497%2Cservice%3AMESHING%2Cstrategy%3A44&sh=4

2 - https://www.simscale.com/workbench/?pid=3015095305875467834&mi=spec%3A4bb539bf-df1c-4fef-9e80-4af987360414%2Cservice%3ASIMULATION%2Cstrategy%3A7

#2

Hi Hakan!

My colleagues Barry (@Get_Barried) & Darren (@1318980) discussed this in this topic already, let me know if that helped: Floating point error compressible 2D diamond airfoil.

Best,

Jousef

#3

Thanks jousef I have checked that topic and created the mesh accordingly. However, when I run simulations, I feel like I am not getting right results. Could you please check my project, what is wrong with it?

https://www.simscale.com/projects/hakandemirel/2d_airfoil_simulation_1/

#4

Hi @hakandemirel

I am not able to open this link. Have you send the correct link to your project?

Cheers,
Ani

#5

Project link:
https://www.simscale.com/workbench/?pid=3015095305875467834&mi=spec%3A5aed47f2-e410-4df7-80a9-3b88b56d58c5%2Cservice%3ASIMULATION%2Cstrategy%3A6&ps=analysis%2FCompressible--oneOf%2FboundaryConditions%2F3

#6

Hi @hakandemirel

Sorry for the late reply. Is there any specific case(mach number) in which you are getting incorrect results or are you having trouble with every case?? I will take a look at your project today and will come with a possible solution asap.

Thanks
Ani

#7

Hi all,

Just my 2 cents as I’ve been really busy these few weeks.

Transonic simulations are notoriously difficult as the progression from “incompressible flow” to “compressible flow” as the flow speed progress through the transitional mach numbers is not simple to formulate.

Haven’t dug more into this area yet but do note that it may not be possible currently on SimScale as you are not able to edit the governing equations to add additional terms to estimate this transition.

I might be wrong but just be wary on this as I encountered a formulation issue while simulating strong shocks where only a specific type of algorithm that can produce the strong shocks can be used (rhoCentralFoam).

I will check back again once more info is stated.

Cheers.

Regards,
Barry

#8

Hi @hakandemirel

Few things that I observed in your simulation

  1. You should perform this simulation for at least 1000 iterations. Currently your endtime is 1000s but the delta T is 10, which means you are simulating for just 100 iteration. You need to decrease the delta T to 1 so that you can atleast simulate your case for 1000iterations.

  2. As suggested by @1318980 you should add inflation layers on the airfoil surface to get better resolution of the flow near the surface to get accurate value of the force.

  3. I think K and Omega values will play a vital role in the convergence of this problem. I am currently simulating your problem with a different k,omega value and will tell you about the quality of results as soon as the run finishes.

Thanks
Ani

#9

Thank you both @Get_Barried and @ anirudh2821998 for your comments.

I actually get a rapid increase in drag coefficient which can be seen in transonic region but simulations still seems not correct.

I just try to get an general image thus did not do precise meshing. I will try again by changing iteration , meshing areas and other parameters.

Thanks
Hakan

#10

Any updates on your project @hakandemirel?

Let us know how things go!

Jousef