Hk. Kytomaa et Sw. Corrington, ULTRASONIC-IMAGING VELOCIMETRY OF TRANSIENT LIQUEFACTION OF COHESIONLESS PARTICULATE MEDIA, International journal of multiphase flow, 20(5), 1994, pp. 915-926
The loss of shear strength of a water-saturated cohesionless particle
bed, known as liquefaction, was imaged in real time using clinical ult
rasound back-scattering in an effort to distinguish liquefied from set
tled states in transient events. In the ultrasonic movies, the liquefi
ed regions were found to be readily identifiable by their characterist
ic small-scale random fluctuations, which are consistent with the know
n phenomenon of particle diffusion in suspensions. The time sequences
were analyzed and found to display an upward propagating interface sep
arating settled from suspended regions, similar to the kinematic waves
that arise in batch sedimentation, although their speeds were measure
d to be up to an order of magnitude greater than the terminal velocity
of an isolated particle. On the basis of this similarity, the solidif
ication process that follows liquefaction was modeled using drift flux
theory and the Richardson-Zaki correlation, which was found to give a
good match with the high measured solidification wave speeds.