I would like to simulate a cleaning process with CFX. The idea is to define particles at the walls of the fluid region and to show, how they are effected by the fluid and transported to the outlet. The next step would be to realise breakup conditions. I read about all the primary and secondary breakup models in CFX, but I have problems to realise it. The particles should keep their position at the wall. If the (drag) forces are big enough the fluid should effect them. Has anyone a idea, which breakup model is adequate for this?

Preety interesting what you want to do. First: there exists no drag forces (says literature) that is taking away the particles from a wall. These are the effects of pressure gradients and finally wall stresses. About your question: nobody (as far as I know) has succesfully realised a simulation of a cleaning process-this means a virtually cleaning test.

Hi,

I agree with Mihai, I think the model you propose will be very difficult to get accurate. You would need a good knowledge of the adhesion forces of the particles to the walls, the forces between the particles and the fluid at various boundary layer thicknesses, a good description of the surface roughness before and after cleaning etc etc before even considering doing this model the way you propose.

A starting point is to simply do a single phase model and somehow relate a variable like wall shear stress to particle removal. This type of model would be possible but whether it tells you anything useful is another matter.

Glenn Horrocks