Session: 14-10-02: Micro/Nanofluidics 2025 II

Paper Number: 167018

Self-Accelerating Non-Diffracting Water Waves 

Self-accelerating beams have been intensively studied on both their fundamental properties and versatile applications in the past two decades due to their fascinating properties, such as self-bending, self-healing, and non-diffraction. While self-accelerating beams have been generated and studied in many different physical wave systems, including optics, acoustics, plasma, and electron beams, self-accelerating water waves have not been well studied yet. Water waves have been serving as an important research playground for studying various important wave phenomena, ranging from quantum field theory to metamaterials. Recently, self-accelerating water wave pulses in the time domain have been experimentally demonstrated. However, spatially self-accelerating or self-bending water wave packets have, to the best of our knowledge, not been published yet. The generation of self-accelerating beams usually requires complex phase masks or delicate phase engineering. Moreover, direct observations of the wave characteristics of such beams cannot be done without advanced equipment. Here, we propose and demonstrate an easy approach for creating and visualizing self-accelerating water waves in a simple miniature ripple tank with a special 3D-printed dipper. The curved dipper represents the involute of the predesigned curved trajectory, which coincides with the curved wavefront of the self-accelerating beams. Using Paul Falstad’s Ripple web applet to simulate the ripple tank and Solidworks to design the dipper, we numerically verified our method. Our experimental results perfectly match with the numerical simulation, and the created self-bending wave packets can be directly observed with the naked eye. By comparing to the spherical wave case, it can be seen that the focal point of the self-accelerating beam doesn’t spread while it’s propagating along curved trajectories, manifesting the non-diffracting feature. Our experiment on self-healing demonstrates that the self-accelerating wave not only can bend over the obstacle but also can reconstruct after it is blocked. More interestingly, we have demonstrated that the generated self-bending water wave packets can be used to manipulate particles of styrofoam along a curved trajectory. We stress that our work reveals a non-trivial relationship between the involutes and the wavefront of the self-accelerating beams of any convex curved trajectories, which is universal to any wave phenomenon. Therefore, our method can be readily extended to any other convex curved trajectories. In addition, another important advantage of our approach is that it is not sensitive to the operating frequencies. We believe that our approach can be easily used to educate the public on self-accelerating beams and find applications in other wave systems, including sound and light. 

Presenting Author: Benjamin Zhang Arizona State University

Presenting Author Biography: Benjamin Zhang is a visiting student in Prof. Sui Yang's lab at Arizona State University

Authors:

Benjamin Zhang Arizona State University
Peng Zhang Arizona State University
Sui Yang Arizona State University