Aerodynamic-Diameter

Equivalent particle diameters for aerosol single-particle dynamics. Migrated from Aerosol.jl@c8c640bb src/single_particle_dynamics.jl:390 (`AerodynamicDiameter` @component). Computes the classical aerodynamic diameter D_ca (the diameter of a unit-density sphere with the same settling velocity) and its continuum-limit approximation (Seinfeld & Pandis 2006, Chapter 9, Eqs. 9.110 and 9.112).