Improved Local Time Step for 2D Shallow-Water Modeling Based on Unstructured Grids
Publication: Journal of Hydraulic Engineering
Volume 145, Issue 12
Abstract
Shallow-water models suffer from relatively high computational costs owing to the Courant–Friedrichs–Lewy (CFL) constraint and (in most cases) the adopted global minimum time step for variable updating. Here, an improved local time step (LTS) scheme is proposed by introducing slight but useful modifications to the Sanders LTS scheme for two-dimensional (2D) shallow-water modeling based on unstructured triangular meshes. The modifications include (1) avoiding an unrealistically large LTS in the case of a vanishing water depth for near-static cells and (2) avoiding spatial variation of the LTS level around a wet/dry front or dynamic/static front. A series of numerical tests show that the improved LTS gives stable and accurate solutions, along with significant reductions in the computational cost. Moreover, the computational overhead due to the aforementioned modifications is negligible. It is expected that the improved LTS scheme will find wide application in 2D shallow-water modeling.
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Data Availability Statement
Codes for estimating the local time steps are available from the corresponding author by request.
Acknowledgments
This research is supported by the National Natural Science Foundation of China (11772300 and 11872332), the Zhejiang Natural Science Foundation (LR19E090002), the Key Project of Changjiang Waterway Bureau (K16-529112-016), the cooperative project between Zhoushan and Zhejiang University (K18-529112-004), and the HPC Center OF ZJU (ZHOUSHAN CAMPUS). Constructive comments from the reviewers are acknowledged.
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Published In
Journal of Hydraulic Engineering
Volume 145 • Issue 12 • December 2019
Copyright
©2019 American Society of Civil Engineers.
History
Received: Apr 30, 2018
Accepted: Apr 9, 2019
Published online: Oct 15, 2019
Published in print: Dec 1, 2019
Discussion open until: Mar 15, 2020
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