Theoretical analysis and nowadays advanced numerical simulations for bedload particle transport widely share a popular assumption: All sediments are spherical and can be simplified as spheres, which apparently differs from reality. In order to explore the shape effects of sediment particles on their transport and to find out the possible consequence originated from the spherical assumption, a particle resolved computational model is established by combining the large eddy simulation for fluid and the discrete element method for the solid particles using an immersed boundary (IB) technique. Using this model, simulations are conducted for spherical and non-spherical bedload particles in both laminar and turbulent open channel flows. Simulation results show that shape of sediment particles has direct influence on the incipient motion in both laminar and turbulent flows. In laminar flows, the widely adopted spherical particles tend to exhibit over 5 times higher traveling speed compared with the non-spherical particles, and over 4 times longer time lag during incipient motion. In turbulent flows, the disk-shaped non-spherical particle yields up to 60% higher travel speed, 50% larger saltation height and 126% longer saltation length compared with spherical particles. The travel modes of non-spherical sediment particles during incipient motion are also analyzed.

理论分析和当今用于床载颗粒传输的高级数值模拟广泛地共享一个普遍的假设：所有沉积物都是球形的，可以简化为球形，这显然与现实不同。为了探究沉积物颗粒对其运移的形状影响，并找出源自球形假设的可能结果，通过将流体的大涡模拟和固体颗粒的离散元方法相结合，建立了颗粒解析计算模型。使用沉浸边界（IB）技术。使用该模型，对层流和湍流明渠流中的球形和非球形床荷颗粒进行了模拟。仿真结果表明，沉积物颗粒的形状对层流和湍流中的初始运动都有直接影响。在层流中，被广泛采用的球形颗粒的行进速度往往是非球形颗粒的5倍以上，而在运动初期的时滞则是4倍以上。在湍流中，与球形颗粒相比，盘状非球形颗粒的行进速度高60％，盐化高度高50％，盐化长度长126％。还分析了非球形沉积物在初始运动过程中的传播方式。初始运动时的时间延迟超过4倍。在湍流中，与球形颗粒相比，盘状非球形颗粒的行进速度高60％，盐化高度高50％，盐化长度长126％。还分析了非球形沉积物在初始运动过程中的传播方式。初始运动时的时间延迟超过4倍。在湍流中，与球形颗粒相比，盘状非球形颗粒的行进速度高60％，盐化高度高50％，盐化长度长126％。还分析了非球形沉积物在初始运动过程中的传播方式。