Measurements of wall shear stress in particle beds when vibrations are imposed vertically along the direction of shear

Abstract

Measurements were made of the wall shear stress in vibrating particle beds when vibrations were imposed vertically along the direction of shear. This work deals with five kinds of particles, and examines the dependency of the wall shear stress on vessel size, vibration frequency in the range 20-80 Hz and the ratio of vibratory to gravitational acceleration in the range 2-8. In order to examine the effect of the wall shear stress on vibrating particle beds, a comparison was made between experimentally measured air pressures at the bottom of the bed and theoretically calculated ones. When the wall shear stress was incorporated in model calculations the agreement between model predictions and measurements improved significantly in beds of large glass beads; however, the agreement deteriorated progressively with decreasing particle size.