Flux-form Eulerian-Lagrangian method for solving advective transport of scalars in free-surface flows

被引：0
作者：
Hu D. [1 ,2 ]
Yao S. [2 ]
Qu G. [2 ]
Zhong D. [3 ]
机构：
[1] School of Hydropower and Information Engineering, Huazhong Univ. of Science and Technology, Wuhan
[2] Dept. of River Engineering, Yangtze River Scientific Research Institute, 23 Huangpu St., Wuhan
[3] State Key Laboratory of Hydroscience and Engineering, Tsinghua Univ., Beijing
来源：
Journal of Hydraulic Engineering | 2019年 / 145卷 / 03期
关键词：
Conservative Eulerian-Lagrangian method; Free-surface flow; Multiscalar transport; Parallel computing; Scalar transport; Unstructured grid;
D O I：
10.1061/(asce)hy.1943-7900.0001578
中图分类号：
学科分类号：
摘要：
A two-dimensional (2D) flux-form Eulerian-Lagrangian method (FFELM) on unstructured grid is proposed for solving the advection equation in free-surface scalar transport models. The scalar concentrations of backtracking points are combined with timeinterpolated cell-face velocities to evaluate cell-face advective fluxes. A G-correction is defined as an additional mechanism to eliminate potential nonphysical oscillations by correcting the cell-face advective fluxes. A flux-form cell update is finally carried out to obtain new cell concentrations. The role of the G-correction in the FFELM is clarified using a test of scalar transport in unsteady open-channel flows. A solidbody rotation test, a laboratory bend-flume test, and a real river test (using a 600-km river reach of the upper Yangtze River) are used to demonstrate the FFELM. The FFELM is revealed in tests to achieve almost the same accuracy as a pure Eulerian-type method [the subcycling finite-volume method (SCFVM)] and a conservative ELM [the finite-volume ELM (FVELM)]. Relative to explicit Eulerian methods, the FFELM uses the information of backtracking points over an extended upwind dependence domain in evaluating cell-face advective fluxes, and allows larger time steps for which the Courant-Friedrichs-Lewy number (CFL) is greater than 1. In the real river test, stable and accurate FFELM simulations can be achieved at a time step for which the CFL is as large as 5. Efficiency issues of the FFELM are clarified using the bend-flume test (193,536 cells) and the real river test (213,363 cells). In solving a transport problem (using 1-32 kinds of scalars and 16 cores), a parallel run using the FFELM is 1.0-3.3 times faster than a parallel run using the SCFVM. The FFELM has a computational cost slightly less (15%-17%) than that of the FVELM. Moreover, the implementation of the FFELM is much easier than that of the FVELM, and extension of the 2D FFELM to its one-dimensional (1D) and three-dimensional (3D) versions is straightforward. © 2019 American Society of Civil Engineers.
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