【作者】 刘旭阳；

【导师】 李世森；

【作者基本信息】 天津大学 ， 港口、海岸与近海工程， 2009， 硕士

【摘要】 泥沙问题是河口海岸地区研究的主要内容,对于河口治理、港口规划、航道整治、疏浚等有重要的意义。国内外学者对泥沙问题做了大量的研究,泥沙模型作为研究泥沙问题的主要手段之一,也得到了快速的发展,从一维、平面二维、垂向二维到准三维,不断的进行完善中。尽管在工程实践中也得到了广泛的应用,也只是近似的来模拟泥沙沿水深的变化规律。客观的自然现象中,水流输沙的运动具有明显的三维特性,而且河口海岸地区的潮流、波浪、径流等又增加了泥沙运动的复杂性。这就使得一维、二维泥沙模型的应用受到限制。因此,三维泥沙模型是泥沙研究发展的必然趋势。本文针对河口海岸地区建立了悬沙输移的三维有限元模型:对三维悬沙对流扩散方程,空间域采用Galerkin有限元法进行离散,时间项采用显示差分法进行离散,把微分方程变为线性方程组,求解采用全选主元Gauss-Jordan消去法求解线性方程组;求解区域采用八结点的六面体等参单位剖分;通过分步积分和Green高斯公式得到满足自由表面和底部的边界条件;对本质边界条件(开边界条件)采用消行修正法进行修正,得到一个线性方程组。本文也介绍了悬沙模型中的各种参数理论的现状,很多是从试验中得到的半经验半理论公式,这就要求我们合理地选取参数来保证我们计算的准确性。用Fortran语言对该模型编写程序,开发得到了可以计算悬沙模型的通用程序。最后采用有解析解的算例进行了验证,结果表明该模型可以用于海岸河口的悬沙输移模拟。更多还原

【Abstract】 Sediment transport is an important content in estuary and coastal study, which has more sense in estuary regulation, port and harbor planning, channel improvement and dredging. Scholars around the world do lots of research on sediment transport. With the development of computer technology, sediment transport model is quickly developed. From 1-D to 2-D and 3-D, it is continuous optimization. Although these have been widely applied, in some cases they can’t simulate exactly. In the natural word, sediment movement is being of 3-d, further more, tidal current, wave and runoff is being more and more complicated. So the 1-D and 2-D sediment model are limited applied. Therrfore, the three-dimensional sediment model must be inevitable trend of sediment research.A three-dimensional mathematical model is presented for the suspended sediment transport using Galerkin finite element method. For the governing equation, i.e. the convection-diffusion equation, the space discrete is performed via the standard Galerkin finite element method and the difference scheme is employed for the temporal discrete The boundary conditions on the free surface and bottom bed are introduced exactly by integrating the diffusion terms using integration by parts and Green’s Theorem. The essential boundary conditions can be satisfied by modifying the coefficient matrix, so we get a solving linear equation. Also this paper introduces the present state of kinds of parameter theory in suspended sediment model, many of them is empirical formula, this requires us to reasonable choose parameters to ensure the accuracy of the calculation.Through the debug, we get the procedure which is writed by Fortran computer language can calculate the suspended sediment transport. Finally, the model is verified by the examples of analytical solution, the results show that the model can be applied in the suspended sediment model of estuary and coastal.更多还原