[diggee]

Hello everyone! I want to simulate VIV experienced by a cylinder that is only allowed to oscillate in the transverse direction to free stream direction. The vibrations are free i.e. motion of cylinder will be solely due to the fluctuating forces acting on it due to vortex shedding. By no mechanism is the cylinder being forced to oscillate. I want to do this through UDF+dynamic mesh as this option is extremely faster than a full blown 2 way FSI simulation. So far I have come across 2 approaches; the more popular approach has a UDF like here. The second approach uses the 6DOF UDF solver, like here. I have the following doubts

1. Since I only want to model free VIV, is the first approach apt for me? In the UDF, things like spring constant and dampness have been defined whose practical relevance I am unable to see for my case. My cylinder is pivoted and free to move in 1 direction in air then why things like k and c?

2. Fluent manual's descirption of 6DOF solver makes it seem perfect for my case but I don't often see users use it across this forum even for cases similar to mine. Moreover the manual says forces are computed by the solver itself than why do people define a spring force even for this solver (see above linked page)? Am I misunderstanding anything here?

Can anyone please help?!