Mass-Transport

Correction factor β for diffusional mass transport to a sphere, valid across all Knudsen numbers from the continuum to the free-molecular regime (Dahneke 1983, Eq. 5.5). Computes the mean thermal velocity c̄, diffusional mean-free-path ℓ_D, diffusion Knudsen number Kn_D, and the correction factor β = (Kn_D+1)/(2Kn_D(Kn_D+1)/δ_m+1) as purely algebraic observed variables. Migrated from Aerosol.jl src/dahneke_brownian_diffusion.jl:33.