Learning Forum

[Harish Bighane]

I need to capture the acoustic mode shape of a fluid section in a Pipe and also check the structural modes and their coupling effect using FSI.
I found two options:
1. Use FSI in Modal acoustics by defining Acoustic region for Fluid and Physics region for Pipe structure.
2. Use Coupled Field Modal analysis by defining separate Physics region for Fluid and Pipe.
Though the frequencies obtained in both the case are same, but the mode shapes are different for Acoustic pressure and Total deformation.
What is the difference between the two methods?

[wrbulat]

I'm not sure about this but... is it possible that by changing the viewing direction of one of these two models by 90 degrees the mode shapes will have the same appearance? I see what looks like "ovalization" in the upper plot and bending in the lower one. If the geometry is axisymmetric (acoustic medium inside a cylindrical pipe) one model might be calculating one of these shapes when viewed along the x axis and the other when viewed along the y axis. Or you might try an isometric viewing direction and creating animations of the mode shapes.

[Harish Bighane]

No. Theere is no problem with viewing direction. Iv'e also attached isometric view of Acoustic mode and Total deformation for both the cases. Can you please share some document for getting better understanding of the two methods.