河床波の発達に伴う浮遊砂流れの乱流構造変化と粒子・流体の相互作用に関する研究

抄録

In this study, we conducted the fluid-particle simultaneous measurements in order to reveal the fluidparticle interaction mechanism in the developing stages of sand dunes. Instantaneous velocity vectors over the growing sand dunes were measured by the discriminator particle-image velocimetory (D-PIV) and discriminator particle-tracking velocimetory (D-PTV), which was developed by Nezu & Azuma (JHE, ASCE, 2004). In this D-PIV&PTV system, the fluid tracers and the sediment particles are discriminated accurately by their occupied particle sizes, and thus, the particle velocity U_p and the fluid velocity U_f can be measured simultaneously.
As the results, turbulence intensities and Reynolds stress became larger with the growth of sand dunes. There exist two coherent eddies behind dunes; one goes along the dune, and the other lifts up from the reattachment point when the kolk-boils occur.