Vortical dynamics in the wake of water strider locomotion
Vortical dynamics in the wake of water strider locomotion
复制标题
DOI：
10.1007/s12650-011-0117-7
复制
发表时间：
2012-05
影响因子：
1.7
通讯作者：
A. Rinoshika
中科院分区：
文献类型：
--
作者：
A. Rinoshika
摘要以往的研究表明，水的水动力推进也是通过其驱动腿产生的半球形偶极涡将动量传递给底层流体的结果。然而，还没有精确的实验测量这些涡结构，以证明涡推进的机制。在这里，我们揭示了涡结构的同时测量水的运动和流体速度场的高速PIV，并提出了一种新的方法来计算涡动能和涡动量。我们发现，在每一个驱动冲程产生的偶极涡的非对称涡结构，推动水前进，和外部的椭圆形涡比内部的圆形涡弱.偶极涡的运动分为两个阶段：（1）向后平移和（2）返回弯曲。通过这种方式，水$>以最小的能量消耗获得最大的速度。由驱动冲程产生的流体旋涡动量占到了水动量的64-90%。图形摘要
AbstractPrevious studies reported that the hydrodynamic propulsion of the water strider also results from transferring momentum to the underlying fluid through hemispherical dipolar vortices shed by its driving legs. However, there are no accuracy experimental measurements of these vortical structures to prove the mechanics of vortical propulsion. Here, we reveal the vortical structures by reporting the simultaneous measurements of the water strider’s motion and the fluid velocity field with the high-speed PIV, and proposing a new method of calculating the vortex kinetic energy and vortex momentum. We found that the asymmetrical vortical structure in each dipolar vortex, generated by one driving stroke, propels the water strider forward, and the outer elliptic vortex is weaker than the inner circular vortex. The movement of the dipolar vortex is divided into two stages: (1) translating backward and (2) return curving. In this way, the water strider obtains the maximum velocity with minimal consumption of energy. The fluid vortical momentum, generated by the driving stroke, accounts for about 64–90% of the water strider’s momentum.Graphical Abstract