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June 11, 2005, 21:53 |
Convergence issue with continuity equation
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#1 |
Guest
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Hi,
I am modeling flow in a microchannel and is experiencing convergence issue with the continuity equation. I tried using a lower under-relaxation factor for the momentum and this does help sometimes but not always. Is there anything that I could do to aid/assist the convergence? Thanks in advance. |
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June 11, 2005, 22:36 |
Re: Convergence issue with continuity equation
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#2 |
Guest
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Hi. I meet the same problem with yours before. I regenerate grid from Gambit to solve the problem. By the way, I find that sometimes increases some under-relaxation factors can improve the convergence. I want also to get some advice about this problem.
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June 14, 2005, 11:35 |
Re: Convergence issue with continuity equation
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#3 |
Guest
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Check mass flux in "report flux" to see whether it is convergent or not
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June 14, 2005, 11:50 |
Re: Convergence issue with continuity equation
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#4 |
Guest
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Yes, the mass flux is convergent. I switched to SIMPLEC for the pressure-velocity coupling and used a higher (0.7) under-relaxation factor for pressure and a lower value (0.3) for momentum. Seems to work out pretty well initially. But when I switched to a finer mesh, all the residuals start being unstable (oscillate). Any advice will be appreciated.
Thanks. |
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June 14, 2005, 23:21 |
Re: Convergence issue with continuity equation
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#5 |
Guest
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Advice: 1 the mesh quality 2 the discretization scheme 3 try to use the coupled solver 4 contact FLUENT for help Good luck
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June 15, 2005, 14:05 |
Re: Convergence issue with continuity equation
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#6 |
Guest
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Agree with John
1) Continuity problems normally come from bad meshing - e.g. adjacent cells spacing differs a lot 2) Check your pressure contour plots to see if there are any sharp discontinuities in the lines 3) Run double point precision |
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June 15, 2005, 17:14 |
Re: Convergence issue with continuity equation
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#7 |
Guest
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Not sure if this could causing the continuity problem - I am using non-conformal meshing...
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June 6, 2018, 02:54 |
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#8 |
New Member
Abhi
Join Date: Jan 2018
Posts: 27
Rep Power: 8 |
Dear Jake, first try using default values. In case you are not getting convergence then go for URF.
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June 6, 2018, 04:41 |
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#9 |
Senior Member
Cees Haringa
Join Date: May 2013
Location: Delft
Posts: 607
Rep Power: 0 |
just how do you end up deciding to answer a 13 year old question?
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