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How to define oscillation of an airfoil?

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Old   March 31, 2008, 13:28
Default How to define oscillation of an airfoil?
  #1
Farid
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I wanna simulate an oscillating airfoil problem. The sinusoidal oscillation equation is like : AOA(t)= Mean(AOA)+ amplitude*sinwt. how will I define this oscillating motion in Cfx-Pre?

Thanks Farid
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Old   April 1, 2008, 17:35
Default Re: How to define oscillation of an airfoil?
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Glenn Horrocks
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Hi,

Providing the oscillation is a small magnitude then the mesh motion in CFX will handle this quite well.

Glenn Horrocks
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Old   April 2, 2008, 08:50
Default Re: How to define oscillation of an airfoil?
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James Date
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Alternatively you could use a time varying inlet U & V velocity components. If you are using a C-Grid with an inlet around the C part of the grid you will need to include a phase shift relating to the location of the inlet boundary nodes. For small amplitude oscillations you can compare/validate your results against Sears/Theodorsen functions.

James
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Old   April 3, 2008, 06:18
Default Re: How to define oscillation of an airfoil?
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cfd novice
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Hi James

Can you please say how can I impose time varying boundary at the inlet in CFX-Pre. I need to impose pressure inlet @ inlet and make it function of time for a duct. I have no idea how do I go about it. Your help will be much appreciated. Thank you
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Old   April 24, 2008, 04:49
Default Re: How to define oscillation of an airfoil?
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CFD-student
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Hello Glenn,

I am trying to define the oscillation of a 2-D airfoil in CFX using the mesh motion feature as you mentioned.

Do you mean using the Specified Displacement option for the airfoil wall boundary condition? If yes, do you have an example of a CEL expression for the X and Y displacement?

Thank you.
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Old   April 27, 2008, 20:07
Default Re: How to define oscillation of an airfoil?
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Glenn Horrocks
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Hi,

"Specified Displacement option" - yes, this is the one to use normally. There is an example of using it in the CFX tutorials (tutorial 20).

Glenn Horrocks
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