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Henrik Ström October 5, 2005 04:44

Heat transfer at wall trap b.c. for DPM?

I was wondering how FLUENT treats the heat transfer when applying the "trap" boundary condition at a wall when using the discrete phase model. The User's Guide says that, for a droplet, "the entire mass instantaneously passes into the vapor phase and enters the cell adjacent to the boundary". Does this mean that the heat needed to do so (the latent heat of the particle) is taken from the wall also?

Thanks in advance for any input, Henrik

Allan Walsh October 5, 2005 12:22

Re: Heat transfer at wall trap b.c. for DPM?
In looking at combution of fuel particles - water, volatiles, carbon, ash - the trap condition released the volatiles, but not the carbon. A wall UDF was needed to account for everything.

But for droplets, the trap condition should release all of the mass. You should be able to check if the latent heat of vaporization is properly accounted for by looking at the volume sum of DPM sensible enthalpy source.

Another way to do this would be if you were modeling water droplets, to have evaporating material be liquid water and then set up a reaction where liquid water goes to gaseous water. Then latent heat is then accounted for in the reaction, which can be set to happen very rapidly.

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