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-   -   Transient Parameter Variation (https://www.cfd-online.com/Forums/fluent/75308-transient-parameter-variation.html)

Milanowski April 21, 2010 15:31

Transient Parameter Variation
 
I'm modeling an airfoil in ANSYS 12.0. I'd like to be able to show the flow responses while changing the angle of attack during flight. What is the best way to do this? I have the angle of attack defined as a parameter in the model.

I've tried defining events in the transient analysis, but I could not come up with a text command to vary a model parameter.

Thank you for your help!

DoHander April 22, 2010 08:45

You can do a simulation for 0 degree, use this as initial condition for the next angle of attack and so on (you will keep the same geometry but you will change the speed components to reflect the new angle, also you need to change the vectors for force calculations if you monitor Cl and Cd). For each simulation keep the results.

If you don't explicitly need an unsteady calculation the above will give you what you want.

Do

DoHander April 22, 2010 08:51

If you want to simulate a real life flight, with sudden changes in angle and unsteady flow you can implement an UDF to automatically change the speeds components for you at a given time. Say at t=0 seconds you have 0 degrees, at t=120 seconds you have 2 degrees ... This will take a lot of processor resources and it is pretty complicated to implement, it can be justified only if your airfoil oscillates or has rapid changes in incidence. Otherwise the first suggestion works best.

Do

Milanowski April 22, 2010 12:37

Thanks Do,

I'll give the first scenario a try and see how it turns out. I've been looking into UDF's, but I'm fairly pressed for time and I'm not sure I'll be able to get anything of value working.


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