Spectral Analyses of the Pressure Wave Generated by the Flow of Granular Materials

A Case Study on a Small Scale Silo

Abstract

The purpose of this investigation is to obtain a basic knowledge of the characteristics and mechanism associated with the generation of a pressure wave by granular materials during mass flow and deformation. The theoretical estimations are made of the amplitude and the natural frequency of the pressure wave due to local sudden changes in strain produced under large applied stresses. The estimations have been compared with the experimental results and a reasonable agreements were found.
The following are deduced from them:
1) The dynamic pressure which radiated from an edge of the sliding plane is estimated by a factor of 1.5 times its initial pressure.
2) The period of the pressure wave is proportional to the radius of wave origin and is inversely proportional to the velocity of the pressure wave.
3) The level value of a peak at the frequency domain of spectrum decay f^-2 of the pressure wave spectrum is proportional to the flow-rate.
4) The natural frequency and specturm decayf^-r at the spectrum of pressure wave depend on the dissipative mechanism of energy.