Duran-Matute M, van Gorp M D, van Heijst G J F
Fluid Dynamics Laboratory, Department of Applied Physics and J.M. Burgers Centre for Fluid Dynamics, Eindhoven University of Technology, P.O. Box 513, 5600MB Eindhoven, The Netherlands.
Fluid Dynamics Laboratory, Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600MB Eindhoven, The Netherlands.
Phys Rev E. 2019 Mar;99(3-1):033105. doi: 10.1103/PhysRevE.99.033105.
We present results of laboratory experiments on the formation, evolution, and wavelength selection of vortex ripples. These ripples formed on a sediment bed at the bottom of a water-filled oscillating cylindrical tank mounted on top of a rotating table. The table is made to oscillate sinusoidally in time, while a constant background rotation was added for some experiments. The changes in bed thickness are measured using a light attenuation technique. It was found that the wavelength normalized with the excursion length depends on both a Reynolds number and the Strouhal number. This differs from straight or annular geometries where the wavelength is proportional to the excursion length. The flow in an oscillating cylinder has the peculiarity that it develops a secondary flow in the radial direction that depends on the excursion length. The effect of this secondary circulation is evident in the radial transport for small values of the Strouhal number or in the orientation of the ripples for strong enough background rotation. Additionally, ripples in an oscillating cylinder present a rich dynamic behavior where the number of ripples can oscillate even with constant forcing parameters.
我们展示了关于涡旋波纹的形成、演化及波长选择的实验室实验结果。这些波纹形成于安装在旋转台上的充满水的振荡圆柱形容器底部的沉积床上。使台子随时间作正弦振荡，同时在一些实验中添加了恒定的背景旋转。使用光衰减技术测量床层厚度的变化。发现用偏移长度归一化后的波长取决于雷诺数和斯特劳哈尔数。这与波长与偏移长度成比例的直线或环形几何形状不同。振荡圆柱体内的流动具有这样的特性，即它会在径向方向上产生依赖于偏移长度的二次流。这种二次环流的影响在斯特劳哈尔数较小时的径向输运中或在足够强的背景旋转下波纹的取向中很明显。此外，振荡圆柱体内的波纹呈现出丰富的动态行为，即使在强迫参数恒定的情况下，波纹的数量也会振荡。
