Investigation of vertical velocity distribution in debris flows by PIV measurement

Abstract

Vertical velocity distribution in some fluid–solid flows such as debris flows has not been well recognized and lacked a commonly accepted form. The particle image velocimetry (PIV) measurement system was employed to investigate the velocity distribution of high-viscosity fluid–solid flows. The velocity distribution was greatly affected by the particles due to the particle-particle collision and momentum exchange between the particle and fluid. Both of them show a similar increasing trend only in the range of the dimensionless flow depth from 0 to 0.7. In addition, based on the log-law model for sediment-laden flows, a modified model was proposed to predict vertical velocity distribution in debris flows. The results indicated that the calculated results were in good agreement with the experimental ones. The coefficient and index for the modified item was about 0.92 and −1/6, respectively.