Nagahiro Shin-ichiro, Hayakawa Yoshinori
Department of Physics, Tohoku University, Aoba-ku, Sendai, 980-8578, Japan.
Phys Rev Lett. 2005 May 6;94(17):174501. doi: 10.1103/PhysRevLett.94.174501. Epub 2005 May 2.
We investigate the condition for the bounce of circular disks which obliquely impacts on the fluid surface. An experiment [C. Clanet, F. Hersen, and L. Bocquet, Nature (London) 427, 29 (2004)] revealed that there exists a "magic angle" of 20 degrees between a disk's face and water surface in which the condition of the lowest impact speed necessary for a bounce is minimized. We perform a three-dimensional simulation of the disk-water impact by means of the smoothed particle hydrodynamics. Furthermore, we analyze the impact with a model of the ordinary differential equation (ODE). Our simulation is in good agreement with the experiment. The analysis with the ODE model gives us a theoretical insight into the "magic angle" of stone skipping.
我们研究了圆盘斜向撞击流体表面时发生弹跳的条件。一项实验[C. 克拉内、F. 埃尔森和L. 博凯，《自然》（伦敦）427, 29 (2004)]表明，在圆盘表面与水面之间存在一个20度的“神奇角度”，在这个角度下，发生弹跳所需的最低撞击速度条件被最小化。我们通过光滑粒子流体动力学方法对圆盘与水的撞击进行了三维模拟。此外，我们用常微分方程（ODE）模型分析了这种撞击。我们的模拟与实验结果吻合良好。用ODE模型进行的分析让我们对打水漂的“神奇角度”有了理论上的认识。
