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Problem in Multiphase setup with phases

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Old   November 6, 2014, 06:01
Default Problem in Multiphase setup with phases
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Nikolaos Babilas
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Hello to everybody, I try to simulate a heat transfer in a boiler with fluent. I have two inlets (air and water lquid). I used the multiphase model so i choose 3 phases (air, water(l), water(v)). I define as primary phase at the tab 'Phases' the water liquid as the maual said. However while i run the calculation, no iterations appears because there is an error that say 'Primary Phase must be the liquid phase' although i have already define as it. Should i change the primary phase
somewhere else or in a tab in setup area?
Also in the boundary i can not define different phases for inlets. i mean that when i change 'inlet velocity air' to 'phase 1' the 'inlet velocity water' becomes automatically 'phase 1'. I guess that i have to fill all the tabs of the phases (and the mixture) and put in some phases volume of fraction 0. i dont know if it is something like that correct.
Sorry for the bad english.
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Old   November 6, 2014, 07:34
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Nikolaos Babilas
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I had finally problem with the initialization. Now i try to run the setup and i confront problems that related to the temperature. For instance, the residuals diverged because of problem in temperature ->decreasing coarsening group size and also increasing relaxation sweeps.i have tried VOF model but i think that the appropriate is the eulerian. I work on the eulerian model using the parameter boiling. For the viscocity i use k-e. i dont know if there is a problem of compatibility.
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Old   November 6, 2014, 10:12
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Nikolaos Babilas
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I think that for this problem it is needed to initialize separately water and air because of the grat difference in temperature. Can someone help me with this trial. I try to find something about advanced initialization but i can't!
Sorry for my english again.
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Old   November 7, 2014, 17:59
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Arindam Singha
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I have exactly same problem, I was running a boiling model. First run liquid water through the model to get the temperature right, then introduce vapor phase, that way you get convergence easily. Also try patching the temperature values at various zones, if you can hand-calculate them.

Hope this helps.
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