A series of physical model experiments is conducted to investigate the flow velocity reduction downstream from fishing net in current. The plane net is fixed on a steel frame, which is 0.3 m in width and 0.3 m in height, and positioned in the center of the flume normal to the flow direction. In the experiments, the acoustic Doppler velocimeter (ADV) is applied to measure the flow velocity behind the plane net. This paper presents the flow velocity reduction behind the plane net(s) with different solidity, spacing distances between two plane nets and plane net numbers. According to the experimental data, there exists an obvious flow velocity reduction downstream from the\ud
plane net and the flow velocity reduction increases with increasing net solidity. For two plane nets with different spacing distances, the average value of flow velocity reduction factor is 0.90 between and 0.83 downstream the two plane nets. As the net number increases from 1 to 4, the minimum flow velocity reduction factor downstream from the\ud
plane nets decreases from 0.90 to 0.68. It is found that there is a close relationship between the flow velocity reduction and the above parameters of the plane net. These results should help improve understanding of flow around the net cage
