方型人工鱼礁周围水流运动的数值模拟研究

采用计算流体动力学(CFD)技术,模拟得到了5种不同来流速度(0.1、0.2、0.4、0.6和0.8 m/s)下方型人工鱼礁(边长为3 m)周围的水流场。铅垂平面上的计算结果表明:当水流贴近礁体迎流面时,水流抬升而形成上升流;不同来流速度工况下,上升流最大速度均约为来流速度的0.64倍,上升流平均速度均为来流速度的0.12倍,而上升流的最大高度为礁体高度的2.62～2.65倍;由于流动分离,在礁体顶面形成一小旋涡区,而在礁体背水面后端形成背涡区;5种来流速度下的背涡区长度均为礁体高度的3.0～3.5倍,而背涡区高度为礁体高度的1.1～1.2倍。水平面上的计算结果表明:紧贴礁体四周为水流减速区,在礁体两侧形成小旋涡区(缓流区),而在礁体背部形成一大旋涡区(背涡区);背涡区内的水流旋涡结构随来流速度大小而变,但背涡区的最大宽度基本不随来流速度的改变而改变,约为礁体宽度的2倍。

Study on numerical model of water flows past a square artificial reef

A three-dimensional CFD simulation is performed to investigate the water flows past a square artificial reef with side of 3 m under the five different incoming velocities(0.1,0.2,0.4,0.6 and 0.8m/s respectively).The numerical results obtained from the perpendicular flow plane show that: an upwelling is formed as water flow approaches the reef,and a small vortex zone above the top surface of the reef as well as a large wake vortex region are created due to the flow separation;the maximum and average velocities of the upwelling current are 0.64 and 0.12 times of the incoming velocity,respectively;the upwelling height,wake vortex height and the length of the wake vortex region are about 2.62 to 2.65,1.1 to 1.2 and 3.0 to 3.5 times of the reef height,respectively.The numerical results obtained from the horizontal flow plane show that: water flow decelerates around the reef,small vortex zones are formed on the two sides of the reef and a large vortex region is produced in the wake of the reef;the wake vortex structures vary with the inflow velocity but the maximum width of the wake vortex region is almost unchanged with the incoming velocity,which is about two times as big as the reef width.