[mcampbell]

All,

I have been modeling a hydrocyclone using particle tracking in CFX. I have had very good success solving the Eulerian phases (water & air) and have good correlation to the well-known Hsieh hydrocyclone that has been heavily researched and documented including LDV experimental results. FWIW I am utilizing the SST turbulence model with Curvature Correction activated. This limits the computational cost while maintaining adequate accuracy. (Even with this relatively simple model it was no small task to achieve a fully developed hydrocyclone with an air core and reach convergence). My streamlines and velocities are right where I expect them.

Now, I am having difficulty getting relevant particle tracking results. I have worked on this extensively and get results that are directionally correct but I lack accuracy. I am very familiar with the ins and outs of particle tracking within CFX - I am using one way coupling since my volume fraction is relatively low <5% (may be stretching it) with the Schiller Naumann drag model. I have run both transient and steady state solution with similar results. My issue is the particles are not ending up where I expect them to go - too many small particles exit through the underflow when they should be traveling with the bulk of the flow to the overflow (95% of the influent fluid exits through the overflow). I have very good empirical data to compare to. I believe the issue is rooted in the details of the particle tracking, namely the particles are not reversing direction when the streamlines do. I am aware that the particles should not follow the streamline exactly BUT 1-5 micron particles in water should be fairly fixed to the fluid (very high drag) at the acceleration in this situation.

Has anyone figured out how to deal with particle tracking with high curvature? Could this be a mesh issue? An integration issue? Other?

Thanks,

Matt Campbell