PIV Experiment on the Gas-Solid Multiphase Flow Relevant to Wind-Blown Sand: Comparison of Velocity Fields of Sand Particles and Air Flow by Simultaneous Measurement

We measured simultaneously the air flow velocity and the suspended sand-particles velocity in the turbulent boundary layer, using particle image velocimetry (PIV), to study the wind-blown sand transport. It is important, in the context of the environmental issues, to elucidate the mechanism of the wind-blown sand, which gives rise to serious problems in arid/desert areas, such as the dust storm and the yellow sand. It is also necessary to understand quantitatively the interaction between the gas phase (air) and the solid phase (sand grains) in the multiphase flow. We found that the momentum exchange between the streamwise and the wall-normal velocities might be inhibited by sand grains and that the streamwise velocity of the gas phase in the multiphase flow was decreased by the momentum exchange between the air and the sand grains. It was observed that gas-phase flow was biased by a cluster of sand grains near a wall.