ABSTRACT
Substituting u 0 into Equation 3.15 from 2.3 gives the equation of particle motion in a quiescent fl uid:
d dt
C D
gn n r r
r r
r
3 4
( )
(4.1)
When the fi rst term (the hydrodynamic resistance force) on the right-hand side of Equation 3.15 from 2.3 is counterbalanced by the second term (the hydrodynamic resistance force), the spherical particle settling under the gravity attains a uniform velocity. It is called the terminal settling velocity.
