| diggee |
June 5, 2018 05:09 |
Dynamic mesh issue in vortex induced vibrations
Hello everyone. I am simulating a cylinder undergoing free vibrations i.e. the vibrations are solely due to the forces generated by vortex shedding. I am using Fluent's inbuilt 6DOF solver to compute the forces experienced by the cylinder and have also enabled the implicit update of dynamic mesh since the solid and fluid motion is so closely coupled.
The simulation is 2D, Re 200K and reduced velocity (Ur) is 4. I am using the smoothing and layering options since my mesh is purely quad, no tri at all. Further I am using the diffusion based smoothing method with parameter as 1 and function as boundary distance.
From literature, I expect the amplitude to be around 0.4D but it is very very less, around 0.001D. Can anyone please explain why is it so less in my simulation? My case and mesh is setup just fine; the simulation for Ur = 2 gave the result in line with literature results. But I must mention that for Ur = 2 I used spring based smoothing but doing the same for Ur = 4 leads to negative cell volume as the mesh moves too much within one time step. Decreasing the time step made no difference so I had to resort to diffusion based smoothing but now the motion is very very less. Can anyone please help me out?
|
