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Open Channel flow (Convergence problem)

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Old   March 4, 2017, 10:11
Unhappy Open Channel flow (Convergence problem)
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Sama Mohammad
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Hi all,

I'm using ANSYS fluent trying to simulate an open channel flow in a rectangular channel, but I can't reach convergence and I'm not able to figure out the problem.

Model: Multiphase (VOF), Open channel flow
Viscous: k epsilon (2eqn)
BC:
Inlet (mass flow inlet), outlet (pressure outlet), and the top boundary as (Pressure outlet), While I have two zones (Air zone and Water zone)
I patched the volume fraction of water as 1 in water zone and 0 in air zone.

I really appreciate your help as I'm stuck in this point and I can't move forward in my research
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Old   March 4, 2017, 11:17
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Ahmed Alkaisi
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Hi sama
First try velocity inlet and no need to patch the air zone
Then try to decrease the URF and time step
Good luck


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Old   March 4, 2017, 11:19
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See this tutorial as well
https://youtu.be/WXgYASXefOk

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Old   March 5, 2017, 09:02
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I've changed the inlet BC to velocity inlet and I follow the solution methods in the given tutorial and Now scaled residuals are really less than previous trials but still not converging. Continuity don't converge even after 2000 iteration, And I'm still working on more trials.
Thank you for your help
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Old   March 5, 2017, 14:13
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Hey Sama,

I think I might be able to help. Interestingly, I have been working on almost the exact same problem you, and noticed similar convergence issues. I even posted about it a few weeks ago. Here is a link to the thread, where I updated it with my solution:

Acceptable residuals of continuity in open channel flow?

Good luck
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