伶仃洋三维潮流输沙的数值模拟

Three-dimensional suspended sediment movement simulation of the Ligdingyang Bay

作者使用垂向坐标变换技术,结合有限差分方法建立了三维潮流输沙的数学模型。为了增加模型的稳定性和减少数值耗散,对悬沙对流扩散方程中的水平对流项采用三阶迎风格式离散。应用本模型对伶仃洋的枯季和洪季的潮流输沙的悬沙场进行了数值模拟,将模拟结果与实测资料进行比较,二者吻合较好。模拟结果分析表明:伶仃洋悬沙运动主要集中在西滩,对伶仃航道影响不大;洪季水体含沙浓度高于枯季;水体含沙浓度沿水深存在浓度梯度,且洪季的浓度梯度明显大于枯季。

By using a vertical coordinate transformation technique and finite difference scheme, the author developed a mathematical model of suspended sediment movement caused by tidal current. In order to increase the model stability and decrease the numerical diffusion, the convective terms of the convectiondiffusion equation of suspended sediment were discretized with a thirdorder upwind scheme. The model was employed to carry out numerical simulations of suspended sediment movement in the Lingdingyang Bay during dry and flood seasons. A good agreement was found between the measured data and computed results. Analyses of the computed results showed that the suspended sediment movement mainly existed in the West Shoal, which had little effect on the Lingdingyang channel. The results also showed that the suspended sediment content in flood season is higher than that in dry season, a gradient of suspended sediment content existed in the vertical direction, and the gradient in flood season is larger than that in dry season.