Air pressure profile and voidage change within vibrating particle beds

Abstract Measurements were made of air pressure beneath and along one side of vibrating particle beds consisting of glass beads of mean diameter 99 μm. In the span of one vibratory cycle, the peak air pressure at 25 mm from the bed surface was found to be higher than that at the bottom (100 mm from the surface) regardless of the magnitudes of vibratory intensity and frequency. A modified compressible gas model, involving variations of voidage in space and time, was proposed to explain the cause of this unusual air pressure reversal.