Learning Forum

[javierbravo9]

Hi,

I'm working on FSI project. I've just read a paper that suggests using FLUID220 as 3D acoustic fluid. I have reviewed that my program is using FLUID221. I don't know well how to change it so I came here for some help. I'm using Modal acoustic for this work.

[HuiLiu]

Both fluid220 (hex) and 221 (tet) are used for acoustics, so it is correct.

[javierbravo9]

Is there a big difference between both fluid models? I know that both have quadratic pressure behavior. I wanted to try with both to see if I get difference answers. So I was wondering If there is a way to change fluid221 to fluid220.

[peteroznewman]

Your mesh has quadratic tet elements. You have to mesh with quadratic hex elements to use fluid220. That means delete your mesh and insert a mesh control Method = Sweep. 

First you should right click on the Mesh item in the outline and Show Sweepable bodies. If the body does not highlight in green, then you need to try Method = Multizone. If that mesh fails, go back to Geometry and in SpaceClaim, (or DesignModeler) split the body until you have a collection of six sided pieces, then use the Share button on the Workbench tab to create Shared Topology. That will then take a Sweep method.

[javierbravo9]

Thank you so much, it worked well.