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| Reporter | jherb | Assigned To | henry | |
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| Priority | normal | Severity | minor | Reproducibility | always |
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| Status | closed | Resolution | suspended | |
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| Platform | linux | OS | SUSE Linux Enterprise Server | OS Version | 11 SP4 |
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| Summary | 0003186: Unphysical temperatures in multi component diffusion |
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| Description | In the attached example, based on OpenFOAM-6/tutorials/combustion/reactingFoam/laminar/counterFlowFlame2D, two gases mix in a closed box. By the initialization with setFields in the lower half of the flow domain there is only H2O (vapor) and in the upper half only N2. Then the gases start to mix by diffusion. All boundaries are set to walls.
At the initialization the temperature field is constant over the whole domain. Starting from the first time step, the temperature shows local fluctuations. The reason seems to be that the enthalpy is diffusing with a different ratio between the two gases other then the molecular diffusion. (Lewis number not equal 1).
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| Steps To Reproduce | To demonstrate it, use the attached case:
blockMesh
cp -r 0.orig 0
setFields
reactingFoam
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| Additional Information | There is a long threat at the cfd-online forum about this: https://www.cfd-online.com/Forums/openfoam/103227-multi-species-mass-transport-library-update.html
It looks like this effect is known for a long time but it seems that it is not mentioned on the documentation on the website, e.g. https://cfd.direct/openfoam/energy-equation/
Are there any plans to improve this situation?
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| Tags | No tags attached. |
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