Dear friends
I'm working on the validation of an FIV case, which for making phase difference between force and displacement, I used an initial velocity in the structural, but after several coupling step, the drag force becomes constant, therefore the structure doesn't fluctuate, the drag force is more than the amount mentioned in the original case which shows vibration in the structure.
any suggestion will be appreciated
Your setup for the flow conditions is not entirely clear from the few mentioned words. You mention a "few coupling steps". Is the analysis type steady-state or transient (must be transient, I guess, otherwise vibration of the solid slab could not be predicted). And if transient - is then the timestep of the solution small enough to resolve the frequency of vibration, e.g. timestep
dear Dr. Thomas Frank
thank you for answering my question, as you said i'm using transient model and about time step in article time has been set 0.03s but i'm using 0.01s, and about the mesh i have tried everything but it didn't bring so much difference in results.
i hope this information would be useful.
Farshad Chegeni : Have you tried to run in transient the pure CFD model (without any structural mechanics part of the simulation) for some time?
Question: How in this case the flow behind the thin solid slab looks like? Can you reproduce under these conditions - for not moving solid slab - a transient vortex shedding? Which turbulence model do you apply (at least SST turbulence model, if not SAS-SST or SBES)?
I guess, that the shown mesh in your attached image is still too coarse in order to be able to reproduce the transient vortex shedding. If I look at it, than the space behind the solid slab is essentially resolved by approx. 10 cells - not substantially more. But a single detaching vortex will have approx. 1/2 of the slab diameter or less. And since in a vortex the fluid flow has strong velocity gradients, one such vortex needs to be resolved alone by at least 10-15 mesh cells. Just a guess from my side in absence of more precise information or an image of the flow field behind the solid slab.
Regards,
Dr. Th. Frank.
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