# Wall heat transfer boundary condition

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 October 15, 2015, 06:29 Wall heat transfer boundary condition #1 Member   Francesco Capuano Join Date: May 2010 Posts: 81 Rep Power: 16 Hi, I would like to model a radiative and convective heat transfer through a wall. In practice, I would need an equilibrium boundary condition of the type , where is the wall temperature and is the environment temperature outside the domain. The wall temperature would then be calculated from (a discretized version of) the above equation to yield the heat flux exchanged at the wall. Is there any available boundary condition to model such problem? Or, did anyone encounter the same issue (and maybe developed a customized b.c.)? Many thanks in advance.

 October 18, 2015, 11:52 #2 Senior Member     Anton Kidess Join Date: May 2009 Location: Germany Posts: 1,377 Rep Power: 30 A mixed boundary condition (i.e. groovyBC) should do the trick. I'm sure you can find a copy&paste solution here on the forum. __________________ *On twitter @akidTwit *Spend as much time formulating your questions as you expect people to spend on their answer.

 October 19, 2015, 06:11 GroovyBC #3 New Member   Napoli Join Date: Oct 2015 Posts: 2 Rep Power: 0 We successfully modeled it with this implementation in file 'T' in directory '0' boundaryField { fixedWalls { type groovyBC; refValue uniform 288; refGradient uniform 0; valueFraction uniform 1; value uniform 288; valueExpression "0"; gradientExpression "h*(T-Tinf)+(sigma)*E*(T*T*T*T-Tinf*Tinf*Tinf*Tinf)"; fractionExpression "0"; evaluateDuringConstruction 0; variables 4 ( "h=50;" "sigma=5.6e-8;" "E=0.8;" "Tinf=288;" ) ; After, we was forced to change the string thermoType>energy from 'sensibleEnthalpy' to 'sensibleInternalEnergy' in file 'thermophysicalProperties' in directory 'constant' for other reasons and we obtained a floating point exception error. What is the problem? Is there an alternative method to implement heat transfer written above?

 Tags heat transfer, radiation, wall boundary condition