Abstract Individual magnetic wax spheres with specific gravities of 1.006, 1.054 and 1.152 were released from rest on a smooth wall in water at friction Reynolds numbers, R e τ = 680 and 1320 (sphere diameters d + = 58 and 122 viscous units, respectively). Three-dimensional tracking was conducted to understand the effects of turbulence and wall friction on sphere motions. Spheres subjected to sufficient mean shear initially lifted off of the wall before descending back towards it. These lifting spheres translated with the fluid above the wall, undergoing saltation or resuspension, with minimal rotations about any axis. By contrast, spheres that did not lift off upon release mainly slid along the wall. These denser spheres lagged the fluid more significantly due to greater wall friction. As they slid downstream, they began to roll forward after which small repeated lift-off events occurred. These spheres also rotated about both the streamwise and wall-normal axes. In all cases, the sphere trajectories were limited to the buffer and logarithmic regions, and all wall collisions were completely inelastic. In the plane parallel to the wall, the spheres migrated in the spanwise direction about 12% of the streamwise distance traveled suggesting that spanwise forces are important. Variations in sphere kinematics in individual runs were likely induced by high and low momentum zones in the boundary layer, vortex shedding in the sphere wakes, and wall friction. The repeated lift-offs of the forward rolling denser spheres were attributed to a Magnus lift.

中文翻译：

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在湍流边界层中释放的有限尺寸球体的运动

摘要 比重分别为 1.006、1.054 和 1.152 的单个磁性蜡球在摩擦雷诺数、Re τ = 680 和 1320（球直径分别为 d + = 58 和 122 粘性单位）下从静止的水中释放出来。 . 进行三维跟踪以了解湍流和壁面摩擦对球体运动的影响。受到足够平均剪切力的球体最初从壁上抬起，然后又下降回壁。这些升力球与壁上方的流体一起平移，经历跳跃或重新悬浮，围绕任何轴的旋转最小。相比之下，释放时没有升起的球体主要沿壁滑动。由于更大的壁摩擦力，这些更致密的球体更显着地滞后于流体。当他们顺流而下时，它们开始向前滚动，此后发生了小的重复升空事件。这些球体也围绕流向轴和壁法线轴旋转。在所有情况下，球体轨迹都限于缓冲区和对数区域，并且所有壁面碰撞都是完全非弹性的。在平行于壁的平面中，球体在展向方向上迁移了大约 12% 的流向移动距离，这表明展向力很重要。单个运行中球体运动学的变化可能是由边界层中的高动量区和低动量区、球体尾流中的涡旋脱落和壁摩擦引起的。向前滚动的密集球体的重复升空归因于马格努斯升力。这些球体也围绕流向轴和壁法线轴旋转。在所有情况下，球体轨迹都限于缓冲区和对数区域，并且所有壁面碰撞都是完全非弹性的。在平行于壁的平面中，球体在展向方向上迁移了大约 12% 的流向移动距离，这表明展向力很重要。单个运行中球体运动学的变化可能是由边界层中的高动量区和低动量区、球体尾流中的涡旋脱落和壁摩擦引起的。向前滚动的密集球体的重复升空归因于马格努斯升力。这些球体也围绕流向轴和壁法线轴旋转。在所有情况下，球体轨迹都限于缓冲区和对数区域，并且所有壁面碰撞都是完全非弹性的。在平行于壁的平面中，球体在展向方向上迁移了大约 12% 的流向移动距离，这表明展向力很重要。单个运行中球体运动学的变化可能是由边界层中的高动量区和低动量区、球体尾流中的涡旋脱落和壁摩擦引起的。向前滚动的密集球体的重复升空归因于马格努斯升力。球体在展向方向上迁移了大约 12% 的流向移动距离，这表明展向力很重要。单个运行中球体运动学的变化可能是由边界层中的高动量区和低动量区、球体尾流中的涡旋脱落和壁面摩擦引起的。向前滚动的密集球体的重复升空归因于马格努斯升力。球体在展向方向上迁移了大约 12% 的流向移动距离，这表明展向力很重要。单个运行中球体运动学的变化可能是由边界层中的高动量区和低动量区、球体尾流中的涡旋脱落和壁摩擦引起的。向前滚动的密集球体的重复升空归因于马格努斯升力。