It represents the ratio of the total mass transfer rate (convection + diffusion) to the rate of diffusive mass transport,[1] and is named in honor of Thomas Kilgore Sherwood.
It is defined as follows where Using dimensional analysis, it can also be further defined as a function of the Reynolds and Schmidt numbers: For example, for a single sphere it can be expressed as [citation needed]: where
A more specific correlation is the Froessling equation:[2] This form is applicable to molecular diffusion from a single spherical particle.
These correlations are the mass transfer analogies to heat transfer correlations of the Nusselt number in terms of the Reynolds number and Prandtl number.
For a correlation for a given geometry (e.g. spheres, plates, cylinders, etc.