Analyses of Three-Dimensional Convective Flow Pattern of Vibrating Powder

Abstract

Nowadays a vibration is often utilized in various industrial powder processes. When a vibration is added to a powder bed, the particles move like a fluid. Various powder flow patterns appear, depending on vibration conditions, including frequency and amplitude. The flow pattern is also affected by particles size, bed size, and aspect ratio. In order to examine the effect of powder amount and container shape on the convective flow of powder in a vibrated powder bed, both numerical simulation based on the discrete element method (DEM) and the Positron Emission Particle Tracking (PEPT) measurement were conducted. The obtained results indicate that the convective velocity of powder is independent of the column size under the present conditions. Then an equation to estimate convective velocity was derived from the simulated results. From the equation, it is conjectured that the convective velocity strongly depends on the vibration amplitude. The average velocities obtained using this equation were compared to the values measured using PEPT. When the frequency was less than 90 Hz and dimensionless acceleration was greater than 5, good agreement between the estimated and measured values was obtained.