Hi,

I am new to CFD, and will do a projet on Fluid Structure Interaction (FSI), mainly on a flexible cylinder undergoes Vortex Induced Vibration (VIV).

CFX or FLUENT, which is better for such task ?

Thanks a lot for the advice ! !

-lee

For simple FSI geometries that dont require mesh adaptation I dont think there is any significant difference between CFX and Fluents capabilities.

If the motion of the cylinder boundary is very simple to calculate given the fluid forces, such that you can prescribe the cylinder motion using a UDF in Fluent or CEL in CFX (e.g. simple 1 DOF motion), then either code is fine. If you need a structural code to solve the cylinder motion given the fluid forces then I would recommend CFX linked to ANSYS. The reason is that FSI using CFX and ANSYS gives an implicit solution, but using Fluent and MPCCI to link to a structural code is an explicit approach (i.e. the structural solution depends on the Fluent solution from the previous timestep rather than the current timestep). For fluid induced vibration problems an explicit approach can give the wrong answer.

I'd agree with Stumpy on this one. If you are trying to pick up flow induced vibrations, you will have to guarantee accuracy at each and every timestep. Only CFX/ANSYS can do that properly because it is semi-implicit.

Thank you so much for your guys' kind comments and advice!

I also shoot a glance at the demo: http://www-harwell.ansys.com/demoroom/demos.php?id=11

I would start from CFX !

you could be sensible and use STAR-CD v4 which includes FV solving of the structure integrated into the same solver - no messy interfaces to another solver !

i did that with star cd v4 .... best solution

i am a very good cfx and ansys user and since i use star cd v4 for my fsi .... i stop using ansys products for fsi...

Yes, this is fine if the limited structures physical model capability in star-cd is good enough.