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SimpleFoam Simulation for windtunnel is not converging

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Old   July 18, 2022, 10:47
Unhappy SimpleFoam Simulation for windtunnel is not converging
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Wanting
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Dear all,

I am simulating the wind flow in a wind tunnel where a cube obstacle is presented. Since I am only interested in the steady state, I am using SimpleFoam for the simulation. However, by monitoring the residual, it seems the simulation is not converged. And also by looking into the results for different iterations, the results are also different.

It seems a relatively simple case since my object has a very simple shape and the wind tunnel is also standard. However, I have tried everything I can think of for several weeks and it is still not working. I will really appreciate it if you could have a look.

The working dictionary and the plot of the residual are attached. Thanks a lot for your help!

Best,
Wanting
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Old   July 22, 2022, 05:14
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Please check quantities like velocity or pressure to see if the simulation is converged or not in addition to using the residuals.
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Old   July 29, 2022, 11:08
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Josh Williams
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Quote:
Originally Posted by Wanting View Post
Since I am only interested in the steady state, I am using SimpleFoam for the simulation.

It seems a relatively simple case since my object has a very simple shape and the wind tunnel is also standard.

Yes flow around a cube is a very simple case, where obviously a cube is a simple geometry. But flow around bluff bodies like a cube is notoriously complex and transient (e.g. von Karmaan vortex streets). Also, as there is a clear fluctuation in your residuals, this seems that you have an oscillating flow. I would recommend switching to a transient solver (pimpleFoam, pisoFoam, etc) and performing time-averaging of the flow to extract whatever your quantity of interest is.
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cube, openfoam 9, simplefoam, wind tunnel simulation

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