Comparisons of the two numerical models of elliptic mild-slope equation for wave propagation in irregular coastal zones
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摘要: 本文分析比较了适于不规则水域波浪模拟的椭圆型缓坡方程两种数值模型。两种数值模型均采用有限体积法离散,分别基于四叉树网格和非结构化三角形网格建立。首先结合近岸缓坡地形上波浪传播的经典物理模型实验对两种数值模型分别进行了验证,并结合计算结果对比分析了两种模型的计算精度和效率。计算结果表明,两种数值模型均可有效地模拟近岸波浪的传播变形;相对非结构化三角形网格下的模型,基于四叉树网格建立的数值模型在数值离散和求解过程中无需引入形函数、不产生复杂的交叉项,离散简单,易于程序实现,且节约计算存储空间,计算效率高。Abstract: In this paper, two numerical models of elliptic mild-slope equation for coastal wave propagation in coastal zones are compared and analyzed. The two numerical models are developed by using finite volume method respectively on adaptive quadtree mesh and triangular unstructured mesh. The numerical models are firstly used to simulate wave propagation and deformation on circle and elliptic shores, and the computational efficiencies are compared and analyzed based on the numerical results. The numerical results show that both of the two numerical models are effective in simulating coastal wave propagation and deformation. Compared with the numerical model on unstructured triangular mesh, the numerical model on quadtree mesh is more concise and easy for numerical implementation as it does not involve complex cross-terms due to model transformation in the process of numerical discretization. What’s more, the numerical model on quadtree mesh is more efficiency in saving computing time and storage space.
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Key words:
- wave /
- numerical simulation /
- elliptic mild-slope equation /
- quadtree grid /
- unstructured grid
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表 1 圆形浅滩地形上两种计算网格下的模型效率比较
Tab. 1 Comparison of the efficiency for the model in two kind of numerical grids on a circular shoal
网格个数 网格步长/m 迭代步数 计算时间/s 计算精度 自适应网格下的模型 7 288 0.025×0.018 75, 0.05×0.037 5 445 4.906 1.0×10−7 Delaunay三角化网下的模型 8 278 0.03 630 6.51 1.0×10−7 表 2 椭圆形浅滩地形上两种计算网格下的模型效率比较
Tab. 2 Comparison of the efficiency for the model in two kind of numerical grids on an elliptic shoal
网格个数 网格步长/m 迭代步数 计算时间/s 计算精度 自适应网格下的模型 11 308 0.335 937 5×0.312 5, 0.167 968 75×0.156 25, 0.083 984 375×0.078 125 445 97.109 1.0×10−7 非结构化网格下的模型 30 618 0.12 630 151.14 1.0×10−7 -
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