Lifting, of particles

The tubular pinch effect can explain much of the anamolous UF data for colloidal suspensions. With UF, the water flux through the porous wall will still carry particles to the wall, but the "lift" of particles away from the wall (due to the tubular pinch effect) will certainly augment the back diffusive mass transfer described by the Leveque and Dittus-Boelter relationships. 

Determining 1 50 is no easy task. In this partially stratified model, it is argued that the lifting of particles by turbulence is strongly influenced by their diameter. Thus, the fines tend to be transported better by the fluid than the coarse solids at the bottom of the pipe. These particles are transported by eddies, and the largest eddy would be equal to the pipe diameter. The pipe diameter was therefore proposed as a reference. The resistance to motion of the solid particles is proposed to be the result of a contact load associated with mechanical sliding friction in the coarser bed and fluid friction associated with the friction velocity of the carrier fluid. In this complex environment, Wilson et al. (1992) defined a new settling velocity as... 

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