Vortex-Induced Vibration Simulation
 

Hi all,

For a project at University I am working on modelling vortex-induced vibrations of a pivoted cylinder in a water flow channel. So far I have determined three possible methods for doing this:

1. Fluent / Transient Mechanical System Coupling
2. Fluent Rigid Body Dynamic Mesh
3. CFX Immersed Solid w/ Rigid Body Dynamics

I am having different problems with all three.
For (1) the solution is very labour intensive, and I do not have access to higher computing power.
For (2) the dynamic mesh often distorts to a degree that the mesh is no longer an accurate representation of the domain.
For (3) the motion of the cylinder often leaves the fluid domain, which in reality is impossible.

I am not looking for a definitive solution to this problem, but ask for advice from those who have tried similar simulations with what I might try to accurately model this system.

Regards,
Jack Callaghan

Hi Jack,

Have you tried doing a FSI simulation using CFX? I did a project for 2,5 years ago and I think that it worked better than FSI with Fluent. If I remember correctly it was not straight forward to get it to work but eventually it worked.

Have you tried any other software that is easier to setup when it comes to FSI simulations? I have used LS-DYNA and when the fluid and structural parts are defined the FSI coupling is activated with one simple command. Their probably exist other similar solvers also but non that I can the name of.

Best regards,
Marcus Timgren

Hi Marcus,

Thanks for the reply.
Correct me if I am wrong but I think method 3 I defined is using FSI in CFX.
Do you know of any tutorial for the method you used so I might compare and see if I am doing anything wrong?

I do not have access to any other CFD software than ANSYS Mechanical, Fluent, and CFX.

Regards,
Jack Callaghan

Hi Jack,

If I have understood you correctly, you do not couple the CFX to ansys mechanical? If I remember correctly I use an approach similar to this https://youtu.be/jNjYuw9mznA.

Also take a look at look at chapter 5 in the following guide, it contains some good advice on how a 2-way FSI simulation is setup. http://148.204.81.206/Ansys/150/ANSY...ce%20Guide.pdf

I hope that this will help you.

Best regards,
Marcus