Drag force spherical bubble

The term mist generally refers to liquid droplets from submicron size to about 10 /xm. If the diameter exceeds 10 /xm, the aerosol is usually referred to as a spray or simply as droplets. Mists tend to be spherical because of their surface tension and are usually formed by nucleation and the condensation of vapors (6). Larger droplets are formed by bursting of bubbles, by entrainment from surfaces, by spray nozzles, or by splash-type liquid distributors. The large droplets tend to be elongated relative to their direchon of mohon because of the action of drag forces on the drops. 

Assuming the bubbles to be spherical, the frontal area Af of the bubble becomes nd2/4. Further, by making use of the expression v = Qjnd2, the drag force can be written in terms of Froude number, the drag coefficient, and the volume of the bubble. Thus... 

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