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September 28, 2011, 07:57 |
Robin BC for T
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#1 |
New Member
Join Date: Oct 2010
Posts: 13
Rep Power: 15 |
Dear all,
one equation in my case is Code:
solve ( fvm::ddt(T) + fvm::div(phi,T) - fvm::laplacian(lambda,T) ); T_inf ...const. Far field temperature alpha ...const. Heat transfer coefficient T_bc ...Temperature at boundary Energy conservation yields q_dot = -lambda (del T)/(del n) = alpha(T_inf - T_bc) which is my BC. * Does such a BC exist? * How should I proceed if I want to implement it? * I know that it is similar to the BC "mixed" but I think mixed cannot account for non-constant lambda. Are there other BCs that might be useful templates? Thank you for any comments! Cheers |
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September 29, 2011, 04:19 |
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#2 |
Member
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I wrote such a BC few time ago (you find the code here) and it actually is a mixed boundary condition.
The idea is simple, just rewriting the equation you wrote (I also add a general thermal power to handle radiation Q) you end up with: h/(h+k*deltaCoeff) * T_w + k*deltaCoeff/(h+k*deltaCoeff) * gradT_w = h/(h+k*deltaCoeff) * T_ref + Q*deltaCoeff/(h+k*deltaCoeff) satisfying both the physical constraint and the form of the mixed boundary condition i.e. VF * T_w + (1-VF) * gradT_w =VF*T_ref + (1-VF) * gradT_ref. So it just set: VF = h/(h+k*deltaCoeff) T_ref = T_ref gradT_ref = Q*deltaCoeff*VF/(1-VF)/h in order to make it work you just have to define in your solver a volScalarField kond to store values for the thermal conductivity (optionally you can define it inside the BC if you like). It was compiled on 1.6.x but I guess you will not have troubles importing it in 1.6-ext or 1.7. Not sure about 2.0, drop me an email if you need a help. Hope you find this useful.
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Cosimo Bianchini Ergon Research s.r.l. Via Panciatichi, 92 50127 Florence - ITALY Tel: +39 055 0763716 Mob: +39 320 9460153 e-mail: cosimo.bianchini@ergonresearch.it URL: www.ergonresearch.it |
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October 10, 2011, 08:47 |
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#3 |
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Join Date: Oct 2010
Posts: 13
Rep Power: 15 |
Hi Cosimo,
thanks so much for writing down your thoughts! You helped me a lot! Regards, Moritz |
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