摘要
为准确求解不规则地形上的浅水方程,建立了一种基于Roe格式的黎曼近似解的具有二阶时间空间精度的和谐离散格式.守恒变量采用加入坡度限制的MUSCL(monotonic upstream-centred scheme for conservation laws)格式进行重构.为保证格式和谐性,引入水面梯度法并基于静水条件构造了底坡项的离散格式:河床梯度采用中心差分格式,而水深则为计算单元附近4个重构水深的平均值.将上述重新调整过的Roe-MUSCL格式运用于3个不规则地形上的水流算例,计算结果均比较理想.
A well-balanced numerical scheme based on Roe's approximate Riemann solver is established to solve the shallow water equations on irregular topographies.In the scheme,the predictor-corrector type finite volume scheme is used and the conservative variables are constructed with the MUSCL scheme(Monotonic Upstream-Centred Scheme for Conservation Laws).Thus the scheme is with second-order accuracy both in time and space.To establish the well-balanced scheme,the surface gradient method is introduced and a new discretization scheme of the bed slope source term has been constructed,in which the water depth is calculated by four reconstructed water depths.The well-balanced scheme has been tested by three examples of flow over irregular bed bottoms and satisfactory results have been acquired.
引文
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