Extension and application of quasi-Direct Numerical Simulation to Bedload Sediment Transport

(1)为了给泥沙波纹形成的数值模拟提供基准数据，我们进行了小型转鼓试验，并对录像资料进行了分析。由此得到的数据提供了以前无法获得的雷诺数小于2.5的颗粒数据，即处于“水力平稳”区域。此外，转鼓比以前的研究要小4倍以上，这将使我们能够更容易地与高分辨率的数值模拟进行比较。(2)我们从理论上估计了碰撞粒子之间间隙中流体惯性的重要性，这在早期的浸没粒子反弹的建模和分析中被忽略了。(3)我们建立了积分关系，它将适用于精确计算自由表面附近的固体粒子和其他固定或移动的固体物体上的力。

(1) To provide benchmark data for numerical simulations of sediment ripple formation, we executed a small-scale rotating drum experiment and analyzed video recordings. The resulting data provided previously unavailable data for particle Reynolds number less than 2.5, i.e. in the "hydraulically smooth" regime. Also, the drum was more than 4 times smaller than in previous research, which will allow easier comparison with highly-resolved numerical simulations(2) We provided a theoretical estimate of the importance of fluid inertia in the gap between colliding particles, which has been neglected in earlier modelling and analysis of immersed particle rebound.(3) We developed integral relations that will be applicable to precisely compute the force on a solid particle near a free surface and other fixed or moving solid bodies.