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- - **Robin BC for T**
(*https://www.cfd-online.com/Forums/openfoam-programming-development/92882-robin-bc-t.html*)

Robin BC for TDear all,
one equation in my case is Code:
`solve` 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 |

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. |

Hi Cosimo,
thanks so much for writing down your thoughts! You helped me a lot! Regards, Moritz |

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