Some help simulating Magnus Force using Fluent

Michele Spinolo

Hi netters,

I'm tring to study Magnus Force on infinite (2D) cylinder using Fluent, but results I obtain doesn't match sperimental datas: in particoular I can't see Negative Magnus force that I should have during the transition from laminar-tourbulent to fully developed toubulent motus, the results Fluent gives to me for both Cd and Cl coefficient (note that I inserted in Fluent correct reference values for my problem) are too far from experimental results, even with no spin for the cylinder (Cl goes rightly to 0 but Cd doesn't give me good results (it should change with Reynolds number during the transition written before, but it's very far from the range it should belong: sperimentally from ~1.3 to 0~0.35, with Fluent always near 0.15-0.25)

I setted Fluent with uncompressible fluids (air max speed is near 20m/s), RSM model with standard coefficients, standard wall function for near wall treatment, double precision solver.

Mesh is very well done with Gambit, near cylinder I used Map scheme and first lenght is 1*10^-5, I can see very well velocity profiles changeing and stall point, I'm quite sure it's not a mesh problem.

I read in some old posts that to simulate more accurately magnus force you should change a coefficent in k-e model, but i don't know which and the correct value, maybe it's the same for RSM model (it solves k-e equations too....).

So at the end of this: can someone help me? did someone already studied Magnus force with Fluent (I can use both 5.4.8 and 6.0.12) and had good results and could help me?

If you need more details please ask.

Thank you very much Michele Spinolo