Gravity-induced collision kernel

G 2 the gravity-induced collision kernel for particles of size a1... 

The gravity-induced collision kernel for spheres of radius a1 and a2 is given by (4) ... 

He have presented a simple procedure whereby one can estimate the stability of a colloidal system undergoing simultaneous creaming and gravity-induced flocculation. This procedure is by no means restricted to only this case. One can easily take into account other particle loss mechanisms, such as shear-induced flocculation or Brownian flocculation. What is required in these cases are the appropriate particle/particle collision kernels, which can be computed by solving the governing convective-diffusion equation. 

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