Why ANSYS FLUENT gives me a wrong answer????
 

Hello, I am Tom Ford.
I am working on Vortex Induced Vibrations of Circular Cylinder in ANSYS Fluent. I am using a UDF (DEFINE_CG_MOTION) for this problem.
I get a right answer from the FLUENT 6.3, But when I use the ANSYS FLUENT version 16, 17, or 18, they give me some answers, but they are all wrong!!!!! I dont know why!!!
I use the same simulation, mesh, and setup in every version of fluent.
I think I have installed a correct version of VISUAL STUDIO for every version of FLUENT.
Can any one help me? What is wrong?
Thanks.