潮流波浪联合输沙及海床冲淤演变的理论体系与其数学模拟

THEORETICAL SYSTEM OF SEDIMENT TRANSPORT BY COMBINED TIDAL CURRENTS AND WAVES AND MATHEMATICAL MODEL OF SEA BED ACCRETION AND EROSION

根据近岸带及河口区潮流、波浪、湍流各自物理尺度的不同，从Ｎａｖｉｅｒ－Ｓｔｏｋｅｓ方程和质量传输方程出发，利用Ｒｅｙｎｏｌｄｓ分解的方法，建立了模拟波浪潮流联合输沙及海床冲淤演变的理论体系，给出了潮流作用下近岸波浪传播方程、波浪作用下潮流运动方程；并通过利用波流合成底部切应力、底层湍流脉动随机特性，得出了波流联合作用下不平衡输沙计算中泥沙起悬与沉降量的确定方法。本文模型应用于“广西合浦围垦工程潮流波浪输沙”、“黄骅港规划一期工程波流计算”等实际工程，结果证明该模型是可行的。

According to the differences among physical scales about tide current wave and turbulence in nearshore zone and estuary, from Navier-Stokes equations and transport equation in fluid mechanics, the flow field and sediment diffusion equations are deduced by using Reynolds decomposition method, a theoretical system of sediment transport by combined wave-tide current and sea bed evolution due to sadiment accretion and erosion is proposed. Controlling equations include: 1) tide current equations under the effecting of waves; 2)wave propagation equations under the effecting of variance of tide level and velocity; 3)sediment diffusion equations transposed by waves and tide current 4)sea bed evolution equations; 5)through composing the shears stress of wave-current and considering the random characters of pulsation and coherent structure in near sea bed turbulence, the quantities function of suspended sediment picked up from and deposited on the bed are determined on the basis of the probability and statistics method. As a practical application, this nonequilibrium sediment mathematical model was used to Engineering of Enclosing Tide Land for Cultivation in Hepu District in Guangxi Zhang Autonomous Region and Wave-Tide Cureent Combined Calculation in Huanghua Harbour in Hebei Province. The obtained results are satisfactory.