Enhanced control of surface wave transitions via trapped air film on multiscale structured surfaces.

The control of the threshold for surface wave transition is a topic of great interest in both scientific and industrial communities. Traditional methods, like installing baffles, for suppressing surface waves often suffer from issues including increased system weight, lack of flexibility and universality, and problems with structural performance. This study utilizes micro/nanoscale surface modifications and millimeter scale slot structure design to trap air film to absorb vibration energy under liquid surface waves. We directly visualized the trapped air film and systematically examined how variations in slot width and depth influence the harmonic-to-subharmonic wave transition. The synchronized correlation between the transition thresholds and air film displacements at varying slot dimensions was established, indicating the significant role of trapped air in shaping the behavior of surface waves. We further discovered that as the liquid thickness increases, the role of the air film gradually weakens until it reaches a critical thickness. This research offers valuable insights into more efficient surface wave control methods, potentially enhancing the design and stability of precision systems in various industries.