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Why Q-criterion does not show the gradients on whole surface?

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Old   September 11, 2020, 12:25
Default Why Q-criterion does not show the gradients on whole surface?
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Hi everyone,

I have performed steady state simulation for a wind turbine blade using STARCCM+. Now, I want to demonstrate the velocity gradients on the blade. Although, I have created an isosurface and Q-Criterion by varying the isovalue from 50 - 1000, but I see that gradients are represented on half of the blade and half blade is taken away. Actually, I want to compare my Q-criterion with the reference Q-criterion from Large eddy simulation. Could you please suggest how to fix this issue - I want to have the gradients all along the blade surface. You can see in the figures, for LES gradients are represented on the whole surface whereas in my case I don't get them throughout.



Thanks for your time.
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Old   September 11, 2020, 13:37
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Quote:
Originally Posted by mazhar16823 View Post
Hi everyone,

I have performed steady state simulation for a wind turbine blade using STARCCM+. Now, I want to demonstrate the velocity gradients on the blade. Although, I have created an isosurface and Q-Criterion by varying the isovalue from 50 - 1000, but I see that gradients are represented on half of the blade and half blade is taken away. Actually, I want to compare my Q-criterion with the reference Q-criterion from Large eddy simulation. Could you please suggest how to fix this issue - I want to have the gradients all along the blade surface. You can see in the figures, for LES gradients are represented on the whole surface whereas in my case I don't get them throughout.



Thanks for your time.



In no way you can compare the steady state simulation to the instantaneous LES field. You must do a time averaging of the LES fields and then compare them.
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Old   September 11, 2020, 13:51
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Originally Posted by FMDenaro View Post
In no way you can compare the steady state simulation to the instantaneous LES field. You must do a time averaging of the LES fields and then compare them.

Thanks for your kind input.I am trying to represent the velocity gradients on the whole blade surface using RANSE; Is not it possible? Since there is void on half of the blade. I have varied the velocity scale and Isovalue for the Q-criterion as well.
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