Three-dimensional velocities induced by wind and ship activity in the near-bottom regions of Lake Taihu
Description
The three-dimensional current velocities (u1, u2, and w) in the lower and upper layers at the monitoring point were measured using a Nortek ADV, with a sampling frequency of 100 Hz. ADV was positioned 5 cm above the lakebed, and mounted on a bottom-mounted holder, facing downward. In this research, the horizontal flow was redistributed into the main stream u1 (x-direction) and the transverse flow u2 (y-direction), based on statistical analysis. The vertical velocity, w, represented flow in the z-direction, with upward movement considered positive. The field survey aimed to discern disparities between wind- and ship-induced disturbances. Data measured under wind influence were collected on July 26, 2018, with wind speeds ranging from 0 to 11 m/s. On July 27, 2018, we conducted 12 different shipping experiments. The shipping scenarios included a full-load (FL) and an unladen (NL) ship, with draughts of 1.8 m and 0.65 m, respectively, passing at distances of 20, 40, and 60 meters from the monitoring point at two speeds: 5 km/h and 10 km/h. The ship used in the field survey is a commonly used freighter in Lake Taihu, characterized by a length of 32 meters, a width of 6.1 meters, and a height of 2.3 meters, with a full-load tonnage of 300 tons. To minimize wind disturbances during the shipping experiments, we selected a period with the minimal wind (vwind = 1.0 m/s).