The fore-and-aft asymmetry of the bubble-particle collision interaction in the non-turbulent regime of multiphase bubble-particle suspension flows

The Navier-Stokes equation governing the water flow around a rising air bubble is highly nonlinear and produces the fore-and-aft asymmetry (FAA) of water streamlines about the horizontal plane of the bubble equator (perpendicular to the direction of bubble rise). In this paper, the effect of FAA on the collision interaction between a particle and a bubble with the fully mobile surface (MBS) or immobile surface (IMBS) and of intermediate Reynolds number (10 < Re < 400) is investigated. Discrete phase model is used to find a particle grazing trajectory around the bubble. The collision angle is calculated based on the contact point between the bubble surface and the particle grazing trajectory. The predicted results of the collision angle agree well with the interception model. The FAA of water streamlines has significantly changed for IMBS in comparison to MBS. It is found that the collision angle is strongly reduced by the influence of the inertial effect caused by water flow and particle mass for both the MBS and IMBS. The outcome of this paper invalidates the simple approximation for fore-and-aft asymmetric water flow around rising bubbles of intermediate Re by a linear combination of foreand-aft symmetric water flows predicted by the Stokes and potential flows.