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Old   August 22, 2005, 06:40
Default combustion modeling
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sara
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i want to model combustion of a candle,we know candle flame is a non_premixed and laminar flame,so I use Transport Species option for modeling,but my model couldn't converged?do you know what's the reason?
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Old   August 23, 2005, 04:23
Default Re: combustion modeling
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Mohsen
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Hi sara, Using Transport Species is correct but there is some poits that you must pay attention to it:1)you should choose "volumetric" option to have reaction and therefore convergence,if you don't do that you'll have only the flow field. 2)three other choices are in the box that the "Thermal Diffusion" is most important option that I think(by experience) is neccessary for diffusion (non-premixed) cases. Hope to Help you
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Old   August 23, 2005, 06:22
Default Re: combustion modeling
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sara
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Thank you for your answer,but I have some other problems too,I would be gratefull if you help me: 1-Is it necessary to active Radiation option? 1-In my modeling I have Pressure-far-field boundary condition and i should input mach no.what's your suggestion (the air around candle is stable and don't have movement) 3-can I use out_flow boundary-condition in this model? Sincerely

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Old   August 24, 2005, 03:47
Default Re: combustion modeling
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Mohsen
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Hi sara 1)Radiation option is not necessary and doesn't have any important effect on the solution (unless the main phenomenon of your problem is radiation)2)I do not think that pressure far field and mach no. would be important for a candle problem.3)what do you mean about out_flow region in this case?
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Old   August 24, 2005, 14:44
Default Re: combustion modeling
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sara
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Hi Mohsen,My project is 2D:suppose a rectangle that a candle is on its lower edge, I model this shape in GAMBIT and subtract candle from rectangle, there is air in this shape and melted-paraffin enter this zone. At first I decided to define BC like this: Left & right edges of rectangle as pressure-far-field, top edge as outflow, the edge that melted-paraffin enters as mass flow inlet, but I faced some problemes: 1-I think it is an incompressible flow(velocity is small),so I couldn't use pressure-far-field BC. 2-In Heat transfer problems I couldn't use out-flow BC. So I tested another appropriate BC,but I couldn't find them, and I couldn't reach to a true modeling.could you please help me?

sincerely

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