Check particle settling velocity via inertia time

[Gorkowski]

See if we should change the base settling velocity calculation to use particle inertia, and if that gives the same answer. This would consolidate settling velocity calc and make it more a derived value.

The settling velocity (v_s) is given by:

    v_s = g * τ_p * C_c

- v_s : Settling velocity [m/s]
- g (gravitational_acceleration) : Gravitational acceleration [m/s²]
- τ_p (particle_inertia_time) : Particle inertia time [s]
- C_c (slip_correction_factor) : Cunningham slip correction factor [-]