Numerical computation of sand dune migration with free surface flow
Numerical computation of sand dune migration with free surface flow
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DOI：
10.1029/2005wr004588
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发表时间：
2006-10-20
影响因子：
5.4
通讯作者：
Shimizu, Yasuyuki
中科院分区：
文献类型：
--
作者：
Giri, Sanjay;Shimizu, Yasuyuki
[1] 本文提出了一种床层自由表面流动的形态动力学模型。该模型以基于物理的方式再现了地床形态的演化和迁移。耦合形态动力学模型的流动模型组件在流向和垂直方向上是二维的，明确地处理不稳定性和非静水效应。与实测结果的比较表明，该流动模型准确地模拟了自由表面流下床形引起的平均流动和湍流结构。通过使用称为三次插值赝粒子 (CIP) 技术的高阶 Godunov 方案来计算纳维-斯托克斯方程的平流阶段，可以增强流动模型的性能。此外，本模型中还包含了带有非线性项的增强型 k-epsilon 湍流闭合，以便更好地预测流动分离区域中的雷诺应力各向异性。在流动和形态动力学模拟的背景下，将非线性 k-epsilon 模型的性能与标准 k-epsilon 闭包进行了比较。非平衡床载沉积物输送是使用沉积物交换过程的欧拉随机公式在拾取和沉积函数方面进行处理的。所提出的沉积物输送方法明确考虑了形态动力学计算过程中的局部流量变化。模型结果表明，垂直网格分布模式影响模拟结果，特别是对于床形态形态学。该模型成功模拟了地床形态演化的一些重要物理特征，例如合并和不对称几何形状。模拟结果与室内实验以及一些常用的床形几何特征预测方法一致。
[1] This paper presents a morphodynamic model for free surface flows over bed forms. The model reproduces bed form evolution and migration in a physically based manner. The flow model component of the coupled morphodynamic model, which is two-dimensional in the streamwise and vertical directions, explicitly treats unsteadiness and nonhydrostatic effects. Comparison with measurements shows that the flow model accurately simulates both mean flow and turbulence structure induced by bed forms under free surface flow. The flow model performance is enhanced by the use of a high-order Godunov scheme known as the cubic interpolated pseudoparticle (CIP) technique to compute the advection phase of the Navier-Stokes equation. In addition, an enhanced k-epsilon turbulence closure with nonlinear terms is incorporated in the present model in order to allow better predictions of Reynolds stress anisotropy in regions with flow separation. Performance of the nonlinear k-epsilon model is compared with standard k-epsilon closure in the context of the flow as well as morphodynamic simulation. Nonequilibrium bed load sediment transport is treated using a Eulerian stochastic formulation of the sediment exchange process in terms of pickup and deposition functions. The proposed approach for sediment transport explicitly considers the local flow variability during morphodynamic computation. Model results show that the vertical grid distribution pattern affects the simulation result, particularly for bed form morphodymics. The model successfully simulates some important physical features of bed form evolution, such as amalgamation and asymmetric geometry. The simulation results are in agreement with laboratory experiments as well as some commonly used prediction methods for geometric characteristics of bed forms.