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Is it possible to apply a Fixed temperature to a Volume of air in CFX? |
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#1 |
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Aja
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Hi,
Is it possible to apply a Fixed temperature to a Volume of air in CFX? I am simulating a problem that air is around a material and this air(volume) have a Fixed temperature in this problem. In fact, the material temperature rise because of this hot air volume . Thanks. |
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#2 |
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You can make a domain isothermal, i.e., set the heat transfer model to isothermal
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#3 |
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Erik
Join Date: Feb 2011
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Yes, that is called a Dirichlet boundary condition. But it doesn't sound like a realistic setup to me.
You would apply a volumetric heat source (subdomain) that is a function of local temperature and intended temperature. Cp * Density *(T.intended - T)/1[s] with a source term coefficient of -1[s]. Again, this does not sound realistic if you are intending to simulate heat transfer. |
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#4 | |
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Aja
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Quote:
In within this mentioned material, there is another volume air then I should apply energy equation because I want to see temperature variation in this material and the existence air in material. |
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#5 | |
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Aja
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Quote:
Thanks. could you please explain more? what is a source term coefficient of -1[s]? where I should use this in CFX? source coefficient is in w/m^3K in CFX not [s]. ![]() |
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#6 |
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Aja
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Air in Material have a initial temperature in this problem but air around the material have a Fixed temperature.
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#7 |
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Gert-Jan
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You can do this in Fluent. It has the functionaity to set the temperature in a certain volume to a fixed value. And if something flows through it, it gets that temperature.
It is realistic? Don't think so. But it can be useful. I used it to model the flow through a burner without taking the complete combustion process into account. I just wanted the temperature rise....... |
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#8 | |
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Erik
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Quote:
Just make it negative 1[s^-1]*(whatever units it wants to be correct). If your function will change the temperature from local to Intended in 1 second. It just linearizes the source term to make it more numerically stable. It should be around equal to the derivative of the functions effect for the best stability I believe. See the documentation for more details. If you don't use source term linearization, you can't use a timestep larger than your source terms effect time, or you will get overshoot and numerical instability. |
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