Cavitation: implementation of Schnerr-Sauer model
I'm working on the implementation of the Schnerr-Sauer cavitation model in our cfd code, but I had some problems with the correct implementation of the source term in the transport equation. My problems are as follows:
If I initialize my flow field with pure liquid, so the volume fraction of the vapour is zero leading to a vanishing source term (in cavitating regions where the pressure is below the vapour pressure) since the radius R become zero. Thus no cavitation occur. This is quite physical behavior since cavitation is linked to the presence of nuclei.
If I initialize my flow field with nuclei (e.g. vapour volume fraction value of 1.e-5) cavitation can occur in regions where the pressure is below the vapour pressure. Now the problem is, that the condensation source term (in regions where the pressure is above the vapour pressure) is non-vanishing leading to a reduction of the vapour volume fraction. In the worst case the vapour volume fraction become negative, which is not physical.
does anyone has experience with this topic? If so, how did you come up with this aspect? Did you implement a source term which is different from what is presented in your papers or did you modify the numerical procedure (finite volume, Euler implicit, upwind interpolation) for the transport equation for the volume fraction in order to keep the volume fraction between the physical bounds 0 and 1?
In ANSYS Fluent, as i worked in that the source term enhances phase change from fluid to vapor and vapor to fluid. The additional source term is greater and smaller than the vapour pressure depending on the pressure linked equations.
Please check it in my work.
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