Nonuniversal velocity fluctuations of sedimenting particles.
Velocity fluctuations in sedimentation are studied to investigate the origin of a hypothesized universal scale [P. N. Segre, E. Herbolzheimer, and P. M. Chaikin, Phys. Rev. Lett. 79, 2574 (1997)]. Our experiments show that fluctuations decay continuously in time for sufficiently thick cells, never reaching steady state. Simulations and scaling arguments suggest that the decay arises from increasing vertical stratification of particle concentration due to spreading of the sediment front. The results suggest that the velocity fluctuations in sedimentation depend sensitively on cell geometry.
Tee
Shang-You
SY
Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.
Mucha
P J
PJ
Cipelletti
Luca
L
Manley
S
S
Brenner
M P
MP
Segre
P N
PN
Weitz
D A
DA