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August 11, 2006, 05:48 |
Flux+Temperature on a wall ?
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#1 |
Guest
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Hello,
I have a question : does anobody know if it's possible to have as boundary condition for a wall both temperature and heat flux ? (For example : a wall at 100°C with a heat flux of 500W/m² on it) Thank you ! |
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August 11, 2006, 08:28 |
Re: Flux+Temperature on a wall ?
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#2 |
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Hello,
I guess that would be too many constraints at the boundary. It is like trying to specify the temperature, pressure and density of a gas at the same time. The moment you fix any two properties, the third is automatically fixed by the ideal gas equation. Likewise, for a given flow system, the moment you fix the wall temperature, the heat flux is fixed. Or if you specify the heat-flux, then the wall temperature becomes a derived quantity. What is the physics behind what you are trying to simulate? Do you really have such a situation? HTH, Raj Kiran |
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August 11, 2006, 08:46 |
Re: Flux+Temperature on a wall ?
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#3 |
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Hello all,
I'm in same situation, I have asked it at fluent support and they have said me that fluent does not support the two conditions. You have to impose one or the other and it is a little bit complicate because when you impose a heat flux you mean that all is radiation but is difficult to impose a quantity for the convection. The surface is also important in this cases because is not the same emiting 2000 W in a small or in a high surface. In fact it is more complicated that seems. I'll try to find out the best choice, I think that there is a tutorial specialized in this terms. |
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August 11, 2006, 09:40 |
Re: Flux+Temperature on a wall ?
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#4 |
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thank you for your answers
Raj, I think you're not right : you can have to specify heat flux and temperature at the same time on a wall, and to have the heat flux does not give automatically the temperature : For example if you want to know the temperature on the other side of the wall, to determine it you must have both temperature and flux. Albert, I think I'll try to make a udf to force fluent to apply both conditions but I don't know if it will work..... |
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August 11, 2006, 09:50 |
Re: Flux+Temperature on a wall ?
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#5 |
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Ok tanphi, I'll look for information about this type of boundary conditions but I thing that an UDF would be the right way...
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August 17, 2006, 05:37 |
Re: Flux+Temperature on a wall ?
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#6 |
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Look for this tutorial:
Thermal Model of Head Lamps using DO Radiation Model. I think it can help. |
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August 19, 2006, 09:06 |
Re: Flux+Temperature on a wall ?
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#7 |
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Conductive heat flux through the solid is driven by the temperature gradient across it. i.e. Qx = -KA dt/dx. And so the two conditions are intimately connected. Hence I wonder why you feel you need both conditions. Please provide details of the case you are studying.
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August 21, 2006, 02:28 |
Re: Flux+Temperature on a wall ?
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#8 |
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I have a bulb that reamins at 900 ºC at the free stream but also emits 2000 W in radiation terms.
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