## Fluids

#### How to couple harmonic and fluent???

• far29
Subscriber
Hello, I want to model a pressure load with different frequencies and thought of harmonic analysis to do so. However I can't find anything (no tutorials, forums or videos) to achieve a 2 way coupling between Ansys fluent and harmonic analysis. Any help would be appreciated. n
• far29
Subscriber
n
• Rob
Ansys Employee
Does the pressure vary because of the solid motion or is it just a pulsing boundary? n
• far29
Subscriber
I am trying to model the vibrations due to the snoring on the artery wall. n
• Rob
Ansys Employee
So, you only need to transfer the vibration motion to Fluent? There's no effect on the shape due to the flow? n
• far29
Subscriber
Basically I am trying the see the effect on wall shear stress. So I need to apply a vibration then check its effect on WSS on fluent n
• far29
Subscriber
I also need to find a way to insert a transfer function. So basically I want to input a certain pressure and get another pressure as an output following that transfer function. Any idea how a transfer function is applicable on ansys? n
• Rob
Ansys Employee
OK, so the solid alters the flow but the flow doesn't alter the solid. You'd need to look at the moving deforming mesh for this and I suggest making sure the near wall mesh is unchanged in your model (ie move the wall & near wall mesh and deform the far field mesh) to improve accuracy. Not sure what you mean by a transfer function, if you want data out of Fluent then you've got various options, profiles and File-Export-ASCII may be easiest to use elsewhere as they're human readable. n
• far29
Subscriber
Thank you for the mesh tip nIf I choose to write an expression for my wall boundary condition where I can input the transfer function, would the material properties of the wall affect the load transmitted? n
• far29
Subscriber
Transition function is an expression I want to input into fluent. Basically it provides a relationship between Pressure 1 and 2 for example. So when I give an input of P1, I should get P2 output following the equation of the transfer function n
• Rob
Ansys Employee
No, as you'd be assigning the motion via the moving deforming mesh. If the material alters the motion you'd need to model or account for that. knows more about the FSI and Mechanical interactions.Re the transfer function, if you know P1 I'd use a UDF to put the P2 value into User Defined Memory or use a Custom Field Function if you want to plot & export it (latter is easier). Expressions aren't quite able to do that (or may just be: I'm testing and have completely lost track of which update is live, what's being tested and what's coming next year....). n
• far29
Subscriber
Thank you for your help n