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Research on the Impact of Boussinesq Coefficient for Numerical Schemes to Model Dam-Break Floods

Author(s): Fan Yang, Dongfang Liang

Linked Author(s): Dongfang Liang

Keywords: Sustainable urban drainage system, urban flood management, community perception, Ho Chi Minh city, social benefits

Abstract: The alternating direction implicit (ADI) model has been thought to be incapable of modeling trans-critical flows, but is still widely used in commercial computing software. This study examines one of the widely-adopted numerical treatments that enable the use of ADI scheme in simulating rapid dam-break flows and helps modifying the Boussinesq coefficient which quantifies the non-uniformity of the velocity distribution over the depth. The treatment partly mitigates the inherent instability of the ADI model when solving trans-critical flows. The test cases consider instantaneous 1-D and 2D dam-break floods on a friction-less and flat bed, with the results by a shock-capturing TVD-MacCormack model used as references. Systematic parametric studies were carried out in this study to assess the influence of the Boussinesq coefficient on the computational results of both ADI and TVD models. The results suggest that with the increase of the Boussinesq coefficient, the amplitudes of the spurious oscillation can be reduced. Meanwhile, the value of the Boussinesq coefficient also influences the propagation speed of the dam-break wave. These results are useful for evaluating the accuracy of the ADI models when simulating rapid dam-break problems. Finally, the paper describes the application of a 2-D ADI model to the flood flows in a densely urbanized area. The results reveal that the increase of the Boussinesq coefficient can significantly reduce the amplitude of the numerical oscillation inherent to the ADI model and the coefficient also influences the extent of the flooding


Year: 2017

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