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GLOBAL ABSOLUTE RESIDUAL for MASS doesn´t converg

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Old   October 11, 2005, 10:59
Default GLOBAL ABSOLUTE RESIDUAL for MASS doesn´t converg
  #1
Boban
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Hi everybody, First I modelled a channel that was 15cm long and in this model I had about 3000000 cells. It was a laminar flow and everything was ok, it converged after 50 or 150 iterations, depending on the velocity. But, this model was to short, as I want to get values not only in the developing region. So I made another model like the first one. This one is 50cm long and there are about 8000000 cells. But this doesnt converge at all. The global absolute residual for mass is increasing all the time, and I dont understand why. Has the amount of cells this influence? All I could do was to start the job as a turbulent flow and then to switch it and restart as a laminar flow. But also this doesnt work always. Does anyone have any idea what should I do? Thanks in advance, Boban
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Old   October 12, 2005, 04:33
Default Re: GLOBAL ABSOLUTE RESIDUAL for MASS doesn´t con
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Fr Ted Crilly
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Dude,

not sure if this will help but:

one thing you should check is the .info file in your project directory, and check the materialwise mass balance figures. you should ensure you have the:

print iteration and conservation controls item in the output controls checked on.

You should be able to see each of the boundary flows and it might help you work out why mass is not convergering,

perhaps a boundary is not acting as it should because of a problem with the mesh.

you fdiff value should tend to 0 or a very small value anyway.

8 Million cells are alot, maybe you should reduce this may be overkill

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Old   November 29, 2005, 16:43
Default need help!!!
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Arif
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Hi, Can anyone please inform me how I can create a sine wave pressure output from a pipe flow where the inlet pressure is constant. Arif DCU Ireland
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