An Experimental Study of the Flow Field Over Wavy Beds Under Oscillatory Flow

Abstract

We use high‐speed cinema Particle Image Velocimetry to measure the oscillatory flow, specifically its instantaneous velocities and vortices at several amplitudes, above three fixed wavy beds in a U‐type tank. By analyzing the intensity and trajectories of vortices with varied phases, the influence of bed topography on the flow near to the beds is discussed. Our results indicate that the topography of wavy beds determines features of the vortex field, trajectories, and the net sediment transport. These conclusions provide new insights into the dynamic mechanism of sediment transport over wavy beds such as sand waves, ripples and dune in offshore areas.

Observation and Theoretical Analysis for the Sand‐Waves Migration in the North Gulf of the South China Sea

“…Typhoon may be the most important factor to cause the sandwave migration to reverse. The previous studies have figured out that the sandwaves migration direction is opposite to the mainstream direction under some wave-current ratio [25,26] . According to the weather data during 2004 and 2005, we count that there was no passing typhoon during 2004 and there were three passing typhoons (David, Vicente and Eagle) during 2005, especially the distance of the David typhoon to the study area was only about 20 kilometers.…”