Coalescence kernels for droplets and bubbles

If the continuous phase is a liquid, the main obstacle to coalescence is the drainage of the film of liquid in the small space in between the two particles. The efficiency is in these cases usually quantitied as a function (generally a negative exponential function) of the ratio of the characteristic time for droplet contact and film drainage. For example, in the case of small bubbles coalescing due to turbulent velocity fluctuations the coalescence kernel assumes the form (Buffo et al, 2012 Laakkonen et al, 2006 Petitti et al, 2010) 

Readers interested in more details for particular systems should consult the specialized literature. 

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