Terminal Settling Velocity

Maximum velocity of an object (i.e. particle) as it falls through air.

At STP, pf = 1.292 kg/m³ and η = 1.729 x 10-5 kg/m/sec

At 25℃, pf = 1.184 kg/m³ and η = 1.849 x 10-5 kg/m/sec

Formula

  • VTS = \( g d^2 (ρ_p - ρ_a ) \over 18η \)
Variable Unit
VTS Terminal Velocity - m/sec
g Acceleration of gravity – m/sec2
d Diameter of a particle - meters
ρp Density of particle – kg/m3
ρa Density of medium (air) – kg/m3
η Viscosity of medium – kg/m-sec

Terminal Settling Velocity

VTS = \( g d^2 (ρ_p - ρ_a ) \over 18η \)
VTS
=
g
*
d
2 (
ρp
-
ρa
) / 18 *
η

Digits of Precision:

m/sec2
m
kg/m3
kg/m3
kg/m-sec