Settling velocity

Description

The terminal velocity of a particle which is falling in the viscous fluid under its own weight due to gravity.
Generally, for small particles (laminar approximation), it can be calculated with Stokes’ Law. For larger particles (turbulent particle Reynolds numbers), fall velocity is calculated with the turbulent drag law.
Analytically combination of the expression for Stokes flow and the turbulent drag law, into a single equation that works for all sizes of sediment, resulted to a formula that successfully tested against the data as well as the empirically curves of settling velocity .
C1 and C2 are constants related to the shape and smoothness of the grains.

Related formulas

Variables

wsSediment settling velocity (m/s)
RReynolds number (dimensionless)
gStandard gravity
DMean sediment diameter (m)
v kinematic viscosity of water (m2/s)
C1Constants related to the shape and smoothness of the grains (dimensionless)
C2Constants related to the shape and smoothness of the grains (dimensionless)