Rohilla Pankaj, Choi Daehyun, Wallace Halley, Yung Kai Lauren, Deora Juhi, Lele Atharva, Bhamla Saad
Department of Chemical and Biomolecular Engineering, Georgia Institute of Technology, Atlanta, GA, USA.
Interface Focus. 2025 May 16;15(2):20240056. doi: 10.1098/rsfs.2024.0056.
Manu jumping, a popular water diving style among M ori people in New Zealand, focuses on creating large splashes. Divers perform aerial manoeuvres such as the 'utkatasana' pose, entering the water in a V-shape, and executing underwater manoeuvres to enhance the splash size. Our study explores the underlying fluid dynamics of Manu jumping and demonstrates how two key parameters, the V-angle and the timing of body opening, can enhance Worthington jet formation. To accurately replicate human Manu jumping, we studied water entry of both passive solid objects with varying V-angles and an active body opening robot (Manubot). The analysis revealed that a 45° V-angle enhances Worthington jet formation, consistent with human diving data. This angle balances a large cavity size and a deep pinch-off depth. The body opening within a timing window of synchronizes the robot's potential energies to be timely transferred to the cavity formation, producing the strongest and most vertical, i.e. ideal, Worthington jets. Based on our experimental findings, we propose a range of parameters for generating the large Manu splashes. These insights offer engineering perspectives on how to modulate underwater cavity dynamics using both passive and active body formations.
毛利式跳水是新西兰毛利人流行的一种跳水方式，其重点在于制造巨大的水花。跳水者会做出诸如“山姿”等空中动作，呈V字形入水，并在水下做出动作以增大水花大小。我们的研究探索了毛利式跳水背后的流体动力学原理，并展示了两个关键参数——V角和身体展开的时机——如何增强沃辛顿射流的形成。为了准确复制人类的毛利式跳水，我们研究了具有不同V角的被动固体物体以及一个具有主动身体展开功能的机器人（Manubot）的入水情况。分析表明，45°的V角能增强沃辛顿射流的形成，这与人类跳水数据一致。这个角度平衡了较大的腔体尺寸和较深的缩窄深度。在 的时间窗口内展开身体，能使机器人的势能及时转移到腔体形成过程中，从而产生最强且最垂直，即理想的沃辛顿射流。基于我们的实验结果，我们提出了一系列用于产生巨大毛利式水花的参数。这些见解为如何利用被动和主动身体形态来调节水下腔体动力学提供了工程学视角。
