Comments on the Ventilation Coefficient

The ventilation coefficient has to do with an atmospheric area’s ability to disperse pollutants. The ventilation coefficient is denoted by f, where f ≥ 1. For a small ice particle, f = 1, because the Reynolds number is effectively zero. Beard and Pruppacher (1971) [1] fitted data from small water drops falling at terminal velocity through a vertical wind tunnel. They got two empirical formulas, which will be shared in Introduction. These equations are for the mean ventilation coefficient f for vapor diffusion. They involve the Reynolds number and the Schmidt number. The Reynolds number NRe is the following:

N_Re = (U*d)/v.

The Schmidt number is:

N_Sc = v/Dv.

Beard and Pruppacher’s empirical equations have in them the Reynolds number and Schmidt number. Nomenclature is omitted.