[clod]

Hi everybody,

I'm trying to simulate the internal flow field of a pressure swirl atomizer. I set up a transient VOF simulation to track the liquid interface coming from the feeding line, and then injected into a chamber where air is present at atmospheric condition. In the middle of atomizer, in correspondence of the vortex core, I expected a low value of the pressure (lower than the out pressure), due to the high swirl velocity, but I found a negative absolute pressure (around -16 bar), that does not lead the liquid to open after the injection (as expected from the experiments for the bc under investigation).
I attached the screenshot of the pressure contour where this problem is showed: I set in Fluent the pressure operating condition equals to 0, so the pressure shown in this picture is the absolute one.

The simulation that I set up is transient and incompressible. As input I set the total pressure coming from the experiments (11 bar), and at the outlet I set the ambient pressure (1 bar). The RSM turbulence model has been set.
I used the SIMPLE algorithm with PRESTO! method to define the pressure.
The grid that I created is composed by only hexahedral elements in that region, with 179 cells along the diameter in throat section.

How can I fix the problem of the negative pressure? Can someone help me?

[ghost82]

Hi,
it should be related to cavitation of liquid; I think that by enabling one of the cavitational model you will solve the negative pressure issue.
However, none of the cavitational model is compatible with the explicit VOF scheme!