The paper presents results of harmonic analysis in studying particle motion in oscillating flows. An approximate equation is derived to solve the zeroth harmonic equation, which governs the effective fall velocity ν¯s, of particles in oscillating flows. The equation reveals that the drag force on the particles is significantly modified by the instantaneous relative velocity between particles and fluids. Three major factors that govern the variation of ν¯s (as compared to the terminal velocity in still water are the terminal velocity Reynolds number, the phase lag, and the velocity amplitudes of the flow and particle oscillations. The dimensionless equation is given. Applying to the sediment suspension under wave action, the analysis suggests that an enhancement of suspension should occur.
[1]
P. Nielsen,et al.
Suspended Sediment Under Waves.
,
1982
.
[2]
T. Kana.
SURF ZONE MEASUREMENTS OF SUSPENDED SEDIMENT
,
1978
.
[3]
G. Wick,et al.
The motion of a small sphere in a rotating velocity field: A possible mechanism for suspending particles in turbulence
,
1977
.
[4]
Hsiang Wang,et al.
Mechanics of suspended sediment in random waves
,
1975
.
[5]
S. Murray.
Settling velocities and vertical diffusion of particles in turbulent water
,
1970
.
[6]
S. Murray.
Simulation of Horizontal Turbulent Diffusion of Particles under Waves
,
1968
.
[7]
Ivar G. Jonsson,et al.
EXPERIMENTAL AND THEORETICAL INVESTIGATIONS IN AN OSCILLATORY TURBULENT BOUNDARY LAYER
,
1976
.