[arehman1289]

Hello,

Im trying to simulate a U-shaped thermosyphon based on this procedure but in starccm+ and with an outer copper casing.

https://www.youtube.com/watch?v=hPeGvczYHMM

In short I have done the following.

1. Three part geometry, of outer copper tube, inner water and air. The inner geometry is divided into two since I want to initialise both regions differently, with air and water.
2. Used the Eulerian multiphase VOF model with multi-component liquid - water as phase 1. Phase 2 was a multi-component gas with air and water vapor.
3. I enable the evaporation/condensation model and link h20 water with that of vapor.
4. I initialise the air region of the geometry with 1.0 mass fraction of air and 0.0 of the others and similarly for the water region.

However I get the error that sum of mass fractions is zero. I dont know why this is happening. If I put random non-zero values, the simulation runs but crashes immediately with AMG solver non-convergence.

Any tips ?

Thank you.

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