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October 25, 2023, 02:18 |
Oscillating Force - External Aerodynamics
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#1 |
New Member
Join Date: Oct 2023
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Hello all,
I have an oscillating drag force in a steady state simulation in OpenFoam (external aerodynamics), see picture. The oscillation is always the same, starting with the first iteration. I therefore believe that it has no physical cause. The simulation also converges normally, and the force curve looks normal except for this fluctuation. Does anyone have experience where this oscillation comes from or how to investigate it further? Thanks a lot! Martin |
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October 25, 2023, 04:12 |
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#2 |
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Join Date: Dec 2021
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Hey
According to the scale, the oscillations are less than 0.001 which is already quite small in my opinion. I am not sure you can get even more stable results with a steadystate simulation. Depending on your conditions, the flow can be unsteady and it will be reflected on the values you monitor and the residuals. I believe these oscillations are mainly due to the limitations of a steady state approach and possibly numerical errors, because it looks otherwise decent. |
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October 26, 2023, 04:14 |
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#3 | |
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Quote:
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October 26, 2023, 08:17 |
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#4 |
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It's not a flow feature - ignore it.
If you really want to go down the rabbit hole, increase the precision of the written data (writePrecision in controlDict), and you will probably find that the variation is even smaller than you reckon. As the earlier poster said - it's just noise, as demonstrated by the "saw tooth" profile. |
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October 26, 2023, 08:57 |
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#5 | |
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Ok, thanks your help guys! |
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converge, force, openfoam, solving |
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