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numerical oscillations in flow parameters

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Old   October 30, 2018, 10:08
Default numerical oscillations in flow parameters
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A. Min
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Hi all

I simulate transient incompressible creep flow on a couple of cylinders to calculate drag force in a special period of time. The drag coeff. oscillates with time (figure) and I don't know why!
Re=1, dt=0.005(Cr=0.8), SIMPLE algorithm, tolerances are set on 1e-12, URFs=0.5, 2nd order schemes are used for divergence terms and time derivative.

I think it is because of Mesh, but I don't know if it is correct or not and how I should improve it.






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Old   October 30, 2018, 11:44
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Can you share the case or at least log file?
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Old   November 1, 2018, 12:23
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Quote:
Originally Posted by pete20r2 View Post
Can you share the case or at least log file?
Thanks for your reply.

Unfortunately the project is not for me!
I didn't save the log file, but I can give you every information you need.

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