Experimental Study of Sediment Incipience Under Complex Flows

Sediment incipience under flows passing a backward-facing step was studied. A series of experiments were conducted to measure scouring depth, probability of sediment incipience, and instantaneous flow velocity field downstream of a backward-facing step. Instantaneous flow velocity fields were measured by using Particle Image Velocimetry (PIV), and an image processing method for determining probability of sediment incipience was employed to analyze the experimental data. The experimental results showed that the probability of sediment incipience was the highest near the reattachment point, even though the near-wall instantaneous flow velocity and the Reynolds stress were both much higher further downstream of the backward-facing step. The possible me- chanisms are discussed for the sediment incipience near the reattachment point.

PIV Measurements and Mechanisms of Adjacent Synthetic Jets Interactions

有改变相对振幅和驾驶电压的相对阶段的邻近的合成喷气致动器的相互作用用粒子图象 velocimetry (PIV ) 被测量，改变相对振幅或驾驶邻近的致动器向量的电压的相对阶段邻近的合成喷气的随后的合并喷气的方向。邻近的旋涡对的 vectoring 机制，吸引影响引起偏转(AICD ) ，被提供解释合并喷气为什么通常是到阶段领先的方面的 vectored 有更高驾驶电压的合成喷气或合成喷气。