drastic increase of temperature in one cell

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 August 24, 2004, 10:44 drastic increase of temperature in one cell #1 ravi Guest   Posts: n/a hello, In my problem at one cell alone there is a drastic increase of temperature as compared to other cells. can anybody tell me what may be the problem or how i can eliminate it. thank you Ravi

 August 24, 2004, 10:54 Re: drastic increase of temperature in one cell #2 Victor Guest   Posts: n/a Maybe the cell that you are referring to is skewed? In other words, the quality of the cell is really poor. /Victor

 August 24, 2004, 12:43 Re: drastic increase of temperature in one cell #3 ravi Guest   Posts: n/a hello, yea, the skewness is high but there are cells with much more skewness than this particular cell and which have not encountered any such kind of temperature rise problem. can anybody tell me how to eradicate my problem. thanking you, ravi

 August 24, 2004, 13:51 Re: drastic increase of temperature in one cell #4 Jason Guest   Posts: n/a Problems with skewness are amplified when they occur in areas of high gradients. If this cell occurs in an area where there's a lot going on, say separated flow or areas of high gradients, then the problem will be huge even if there are areas with worse skewness. I've also seen problems where certain turbulence models will cause a small part of the model to "blow-up" while other turbulence models don't have a problem with it. You can also try turning off the energy equation until you start to reach a reasonable solution. The skewness is probably the reason you're having the problem, but it's being amplified by what else is happening in your model. Hope this helps, Jason

 August 27, 2004, 10:35 Re: drastic increase of temperature in one cell #5 darin Guest   Posts: n/a Occasionally, ignoring the secondary gradient of temperature will help with the convergence. To turn it off issue the following command: (rpsetvar 'temperature/secondary-gradient? #f) Darin

 August 28, 2004, 08:39 Re: drastic increase of temperature in one cell #6 ravi Guest   Posts: n/a Hi, Can u please eloborate where exactly should i give this command in FLUENT

 August 29, 2004, 19:52 Re: drastic increase of temperature in one cell #7 darin Guest   Posts: n/a Simply type the command in the text-user-interface window. (rpsetvar 'temperature/secondary-gradient? #f) In response FLUENT will output to the text window temperature/secondary-gradient?

 August 30, 2004, 22:58 Re: drastic increase of temperature in one cell #8 Anton Guest   Posts: n/a Is this a transient or steady problem? If it's transient, try reducing the time step by an order of magnitude and see the temperature drops in that cell. You may also want to adapt that cell and some of its neighbours to give Fluent at better shot at calculating the gradients through there, if in fact they are high there.

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