The Effects of Wall and Concentration on the Terminal Velocities of Solid Particles

Abstract

The terminal velocities, which are available for the analysis on the hydraulic transport of solid materials as the important parameters, are investigated experimentally about the retarding effects of pipe wall and of concentration of materials. About the effect of wall on the falling velocity of a single particle, the experimental results are in good agreement with the theoretical ones for Re «1, where Re is the Reynolds number based on the diameter of the sphere. For 1⪅Re⪅100, this effect is greatly influenced by Reynolds numbers, but it is independent of Re for Re⪆100. These results are discussed in connection with the flow pattern around a sphere. In the case of a crowd of particles, the floating velocities, which can be measured easily, are applied as the terminal velocities and the correction formula is obtained for the wall and concentration effects.