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- - **Convective boundary condition**
(*http://www.cfd-online.com/Forums/openfoam-solving/58527-convective-boundary-condition.html*)

Dear OF community,
I'm tryiDear OF community,
I'm trying to implement a convective boundary condition in OF. Essentially this condition should be applied in a solid domain and should guarantee the coherence of thermal fluxes at the interface between the solid and a hypotetic fluid. This condition should respect the known equation: -k*dT/dn = HTC*(T-T_fluid) Where k, HTC and T_fluid are parameters of the boundary condition (I think to have succesfully loaded them in my BC), and T and dT/dn are respectively the gradient and the value that I must impose. From which BC should I start to obtain my BC? I tried to start from BC derived from fixedValue, fixedGradient and mixed, but I do not know how to impose a linear combination of two fields like T and dT/dn and where impose it. I have tried some tricks: ---- Starting from fixedValue-derived BCs I try to discretize the gradient as (T_to_set - this->patchInternalField()) *this->patch().deltaCoeffs()) getting an equation in "T_to_set", the value that I try to set as BC. ---- Starting from fixedGradient-based BCs I try to discretize T as (gradient_to_set + *this->patch().deltaCoeffs()) + this->patchInternalField() getting an equation in "gradient_to_set", the value that I try to set as BC. Unfortunaley these triks had no results and I get no result, also for some problem related to type mismatch during compiling. I do not know how to start implement this BC starting from mixed-BC or if the trikc that I have followed are reasonable http://www.cfd-online.com/OpenFOAM_D...lipart/sad.gif Can you help me? Best regards Andrea |

Hi Andrea,
I think you can Hi Andrea,
I think you can have a look at either 1. the mixed-derived advective b.c. in OF 1.5 or 2. [Advertisement] the fixedGradient-derived convectiveOutlet b.c. I posted here on Sep. 05, 2007. 1. is much more sophiscated but may require a bit of patience to read. Takuya |

Hi Takuya,
Thanks for your Hi Takuya,
Thanks for your advise. I will check these boundary conditions and start from them! Andrea |

Hi Andrea,
I am interested in this convective boundary condition too. Have you finished it? I am study the heating process of a solid, which has several heating channels for hot gas or hot oil flowing through. So the boundary condition at the channel wall shuold belongs to the third-class, just as you described above: -k*dT/dn = HTC*(T-T_fluid) Please give me some suggestions. Thanks in advance. Regards, Jitao |

Hi Andrea,
I am also interested in implementing the mixed heat transfer BC. Did you manage to make it? rgds Bjorn |

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