hy everyone i would like to know why i have divergence when i use 2 densities one for solid and one for liquid which is the case for most pcm. if i use one density for both phases i get convergence even with boussinesq approximation, but if i use 2 densities it doesnt work, please can you help me at this point, thanks.
Dear Othmane Rbiyah Instead of using two discrete density values, try defining a continuous density function to get better convergence.
Enable the "VOF" model, and enable the "Continuous Surface Force" option, which allows the density to vary smoothly across the interface. You can also set the "Surface Force Ratio" to control the width of the transition zone between the solid and liquid phases.
A steep variation in density across the interface [where the phase change takes place] may lead to divergence, I guess...
thanks mister Prince Abraham , it does help indeed.
what if i have two different fluids, for exemple water as htf in inner tube and pcm in outer tube, how can i manage these fluids in vof model in order to assign them to each cylinder. thanks
That's possible by defining the number of eulerian phases equal to the number of fluids in the analysis. We can define the volume fraction of that particular fluid as 1 in that specific inlet/boundary.
If you don't have a flow boundary, you can also specify the fluid that is available at the initial timestep by patching it after initialization.
I hope the following video tutorial will help you understand and define the different phases of VOF. Also, the patching with any of those fluids at the initial timestep.
https://youtu.be/QgQTaXuPmbI
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