Study on Turbulent Structures in Typical Regions of Lake Taihu, China

Turbulence bursts play an important role in turbulence production and transportation. Turbulence structures in turbulent boundary layers shows various bursting phenomena and make different contributions to momentum flux and sediment turbulent flux in natural geophysical flows, so this paper study the differences in two sites of Lake Taihu, using data collected from Acoustic Doppler Velometer (ADV). Statistical and quadrant analyses reveal the anisotropic and intermittent nature of momentum flux and turbulent sediment flux. In current-wave main region, the occurrence probability in time of four types of bursting motions were almost the same, but ejection and sweep make large contributions to Reynolds stress. It’s sweep and outward interaction make sediment suspension and transport. The waves increased the vertical fluctuations and sediment suspension. However, in current-main with many plants region interactions make large contributions to Reynolds stress. Interactions occur more than ejection and sweep motions, and make large interactions of momentum flux. For the turbulent sediment flux, it’s ejection and interactions make large contributions. Ejection stripe in East Taihu Bay can cause less sediments suspension, in central zone sweep caused sediment suspension, but outward interaction contributes to sediment transport more in both conditions. It is an important step for turbulence constructers and sediment suspension study to understand the spatial, temporal and frequency characteristics of sediment suspension events in relation to turbulent fluctuations, both in structural form and in temporal distribution.