How to patch species mass fraction in fluent for a converged solution?

Vidzz22 · March 30, 2023, 07:51

I have completed a multiphase simulation (VOF) - Free surface type and obtained converged solution. The two phases are air and water. Now I am introducing three species in water phase within the same case setup. After defining the materials, I patched the mass fraction of species 1, 2 and 3 in all zones. I expected that the profile of mass fraction of the species to be same as that of the volume fraction of water in all grids of the mesh. But I am not getting the same profile. I request you to kindly help me out on finding the possible reason for the same.

andrew-c · April 12, 2023, 15:45

Can you attach some images of the species mass fraction profiles and the water volume fraction profile in the flow?

If the species mass fraction profiles extend outside of the water volume fraction profile, try instead to view the profile of the species mass fraction (mixture level).

If the species mass fraction profile inside of the water profile is not what you expect, it may be an issue of diffusion within the water phase. You can check your diffusivity values for accuracy. Also note that, depending on the characteristics of your model, the species mass fractions may not exactly mimic the profile of water in every physical case.

If you attach some images, I may be able to offer some more suggestions

March 30, 2023, 07:51	How to patch species mass fraction in fluent for a converged solution?	#1
Vidzz22 New Member Vidya Muthulakshmi M Join Date: Aug 2020 Posts: 7 Rep Power: 6	I have completed a multiphase simulation (VOF) - Free surface type and obtained converged solution. The two phases are air and water. Now I am introducing three species in water phase within the same case setup. After defining the materials, I patched the mass fraction of species 1, 2 and 3 in all zones. I expected that the profile of mass fraction of the species to be same as that of the volume fraction of water in all grids of the mesh. But I am not getting the same profile. I request you to kindly help me out on finding the possible reason for the same.

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April 12, 2023, 15:45		#2
andrew-c New Member Andrew Join Date: Dec 2022 Posts: 29 Rep Power: 3	Can you attach some images of the species mass fraction profiles and the water volume fraction profile in the flow? If the species mass fraction profiles extend outside of the water volume fraction profile, try instead to view the profile of the species mass fraction (mixture level). If the species mass fraction profile inside of the water profile is not what you expect, it may be an issue of diffusion within the water phase. You can check your diffusivity values for accuracy. Also note that, depending on the characteristics of your model, the species mass fractions may not exactly mimic the profile of water in every physical case. If you attach some images, I may be able to offer some more suggestions