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Old   October 18, 2004, 21:52
Default Urgent help
  #1
ahourri
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Does fluent has limits in its computation? Can't get convergence and mass balance with hydrogen flow (mass flow rate 7e-5 kg/s and velocity 0.022 m/s)in transient mode. My model works with 100 times the same mass flow rate. Any idea will be greatly appreciated
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Old   October 19, 2004, 02:47
Default Re: Urgent help
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SAM
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describe u physicl model
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Old   October 19, 2004, 04:27
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dumb
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use double precision if u think it is a prob of ur value too low.

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Old   October 19, 2004, 08:00
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SAM
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mass is extensve property. unlike the termprature and pressure

please coudl u describe ur problem.i.e physical model, boundary conditions, any assumption. like symetry or periodic

regards

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Old   October 19, 2004, 10:33
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Satyam
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Use double precision solver
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Old   October 19, 2004, 14:30
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ahourri
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My set up is a rectangular configuration with walls everywhere and three windows. One window in the ground is set as mass flow rate, one in the ceiling is a pressure outlet and another one in the front wall as pressure inlet. I am modeling a very simple gas dispersion problem. I am using parallel computers network.
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Old   October 19, 2004, 20:11
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dumb
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mass flow inlet and pressure inlet and one pressure outlet, ... together they seems to be creating problem ... u might want to consider another combination ..or try increasing number of iterations per time step (they should be quite large to get these together workign well) ...
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Old   October 20, 2004, 21:04
Default Re: Urgent help
  #8
ahourri
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I changed the mass flow rate to pressure inlet which gives 7.1e-5 Pa at the pressure inlet (5.3e-7 Torr). I don't know if the NS equations still hold at that low pressure.
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