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Heat Flux UDF in 2-Phase Flow with Solidification

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Old   September 30, 2014, 09:17
Default Heat Flux UDF in 2-Phase Flow with Solidification
Adam James
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I'm looking to use UDF's for my (thermal) wall boundary conditions using Fluent only I'm not sure how exactly to go about it, particularly when it comes to accessing the relevant solver arrays.

In more specific detail, the problem I'm studying considers two phases, with melting/solidification also activated such that one of the two phases, "liquid-solid" in the fluent materials database, can solidify through heat loss. To date I've just used a mixture of adiabatic and fixed temperature thermal boundary conditions but I think I would like to write a custom boundary condition which expresses the heat flux normal to the surface, with respect to the phase fraction averaged (mixture) thermal conductivity. q = -k(mix)*deltaT. In reality I will probably use a mixture of solid (k of the BC) and fluid (k of the phases) thermal conductivities

My first question therefore is how do I access the thermal conductivity (mixture) variable in a UDF?

If I initialise the temperature field with a value of 300K, for example, how do I then access the temperature on the faces of the boundary condition? This is such that I can determine the deltaT relative to a fixed freestream temperature to enforce the q Neumann BC.

My final question for now, particularly to those with more UDF experience, is should I be concentrating my efforts on the DEFINE_PROFILE or DEFINE_HEAT_FLUX? I think the latter.

Thanks a lot.
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