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Automatically applied heat flux due to species flux

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Old   November 17, 2021, 10:12
Default Automatically applied heat flux due to species flux
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The species solver supports three types of boundary conditions, here's a table from the manual:

Table 31: Properties of the Wall Species Option
  1. Impermeable: Specifies the boundary as impermeable.
  2. Specified Flux: Specifies a species flux at the boundary. The energy that is associated with the wall species influx or outflux is appropriately added.
  3. Specified Value: Specifies a species mass fraction at the boundary.

I'd like to ask how the highlighted energy is calculated and what is the physical reasoning behind such a heat source/sink. I'm trying to model evaporation and am applying the latent heat of evaporation as heat flux profile, but this automatic heat due to species flux at a boundary seems to be superimposed to what I prescribe. To reproduce this just prescribe a species flux at a boundary and plot the boundary heat flux on the same boundary. The energy solver must be switched on. Thanks for any clues!
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Old   November 19, 2021, 06:08
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When you remove a species ( for instance 10 droplets of water) at the wall, then you also loose the energy of the removed species in your flow domain.
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Old   November 19, 2021, 08:49
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Would you say it's the enthalpy then, as in \dot{Q} = \sum _i \dot{m}_i \cdot c_{p,i} \cdot \Delta T, whre i are all species? What would be the reference temperature though, 0 Kelvin? I also noticed there's a field function called ThermalDiffusionFluxEnergySource but I couldn't find any documentation on it.

Last edited by FliegenderZirkus; November 19, 2021 at 10:39.
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Old   November 22, 2021, 10:53
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This look right. I expect, that ccm+ does this calculation automatically.
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