Learning Forum

[HHK1992]

Hi,

I hope you all are doing good.
I am trying to simulate the flow through a wind tunnel and measure the aerodynamic force coefficients of an airfoil placed at the test section of the wind tunnel. I need to do this at various angles of attack.
I know that adjusting the flow direction (and keeping the airfoil horizontal) can do it (PFA pic1). But, this does not seem to be the right method for the simulation of the flow through the wind tunnel (PFA pic2), especially at higher angles of attack.
Does anybody know how to adjust the angle of attack in the wind tunnel simulation without remeshing the geometry for each angle of attack?
Do I need an overset mesh for this?
Please let me know. Thanks in advance.

[DrAmine]

You just provide the adjusted inflow direction on your far field boundary or Inlet as you know the angle of attack.

[HHK1992]

Hello Sir,

Thanks for the reply. 
So, you are suggesting to adjust the flow direction (in case of wind tunnel simulation) to get the angle of attack? Similar to the isolated airfoil case (with far-field BC)? Will it cause any problems?
I thought I might have to rotate the airfoil geometry in the wind tunnel simulation, which appeared to be appropriate.
Kindly let me know.

[DrAmine]

That is the way actually this kind of investigation is done (far field flows). For wind tunnel I would rather however rotate the mesh / Geometry. 

[HHK1992]

In that case, could you please tell me how to rotate the geometry without remeshing it?
I am hoping to change the AoA from 0 to the stall angle. Should I make two cell zones? What kind of interface will be appropriate?

I appreciate your time and suggestions.

Thanks in advance.

[Kalyan Goparaju]

Hello, 

Here is a video tutorial of how to setup the problem that you are describing. Hope it helps. 

https://www.youtube.com/watch?v=G0zAHv0rEa8

Thanks, 

Kalyan

[HHK1992]

Hi,

Thanks for the video. It is really helpful!

 

I prepared a structured mesh and the calculation is steady-state in my case.

Anyhow, I will try it out.

 

[Kalyan Goparaju]

I am glad it helped. Can you mark the answer as solved so that it will help others?

Thanks, 

Kalyan

[HHK1992]

Ok. I will do that.

For others who may try this, the following will be useful too.

https://www.cfd-online.com/Forums/fluent/226649-wind-tunnel-simulation-varying-angle-attack.html

[Abutunis]

Hi Kalyan,nThanks for the video. nWould it be possible writing the lift and drag to a file at the end of each angle of attack iteration.nnThank younAzizn

[Rob]

As they're updating the solution either output as parameters, monitor lift & drag during the run or do the calculation manually at the end. Remember that coefficients require the reference values to be set appropriately. n