I'm working on a modification of the interFoam solver that considers isobaric expansibility of both phases.
So my modified VOF and pressure correction equations look like:
where is velocity divergence computed from the continuity equation.
The problem with this formulation is, that it is not conservative and requires consistent and accurate calculation of the source terms and . For now it works fine within in each phase, but I still have considerable mass imbalance in the interface region.
The second formulation I try to implement is a conservative one. VOF equation works well:
But I get pressure-velocity-oscillations if I solve following pressure correction equation:
It looks like the classical chessboard problem (cartesian mesh), which I thought shouldn't be there because of the Rhie&Chow-like discretization of pressure. And that's actually my question to you: why does it happen and how could I prevent it?
Can anyone help me with a smart advice?
Update: reducing the convergence criteria (i.e. from 1e-08 to 1e-12 for p_rgh) reduces the pressure oscillations dramatically, but still I'm interested to know where do the oscillations come from?
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