Abstract
A two-phase flow model based on the mass and momentum conservation is presented, which can simulate the fluid and sediment movement on a flat bed under sheetflow conditions. The governing equation in the vertical direction is modified by considering the influence of static normal intergranular stress. Horizontal pressure gradient is modified in terms of sediment concentration. A criterion is introduced to decide the temporal variation of the still bed level during a one-wave cycle. Vertically parabolic eddy viscosity and corresponding sediment diffusion coefficient are assumed. Numerical results include initial validation comparisons with the existing experimental data from Horikawa et al. [1982], All measured properties, such as the concentration, sediment velocity and sediment flux are reproduced quite well. Further investigations on the experimental data of Delft Hydraulics [Ribberink and Al-Salem, 1995; Dohmen-Janssen, 1999] cover a wide range of pure sinusoidal wave and combined wave/current flow conditions for different sediment sizes. The numerical results are satisfactory with respect to the measured time-varying and time-averaged concentration distributions both in the sheetflow layer and the suspended layer. Taking into account the various experimental measurements, the present two-phase flow model shows the significant superiority over an existing two-phase flow model [Mina and Sato, 2004], Comparison between the measurement and the present simulation for sediment flux and net transport rate is also performed.
Published Version
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