Publication Date:
2017-12-29
Description:
Xia et al . [2017] proposed a novel, fully-implicit method for the discretization of the bed friction terms for solving the shallow-water equations. The friction terms contain h –7∕3 (h denotes water depth) which may be extremely large, introducing machine error when h approaches zero. To address this problem, Xia et al . [2017] introduces auxiliary variables (their Eqs. (37)–(38)) so that h– 4∕3 rather than h –7∕3 is calculated and solves a transformed equation (their Eq. (39)). The introduced auxiliary variables require extra storage. We implemented an analysis on the magnitude of the friction terms to find that these terms on the whole do not exceed the machine floating-point number precision, and thus we proposed a simple-to-implement technique by splitting h –7∕3 into different parts of the friction terms to avoid introducing machine error. This technique does not need extra storage or solve a transformed equation and thus is more efficient for simulations. We also showed that the surface reconstruction method (SRM) proposed by Xia et al . [2017] may lead to predictions with spurious wiggles because the reconstructed Riemann states may misrepresent the water gravitational effect.
Print ISSN:
0043-1397
Electronic ISSN:
1944-7973
Topics:
Architecture, Civil Engineering, Surveying
,
Geography
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