Calvert Ross, Mol Jessamy, Sutherland Bruce R, van den Bremer Ton S
Faculty of Civil Engineering and Geosciences, Delft University of Technology, 2628 CD, Delft, The Netherlands.
School of Engineering, University of Edinburgh, Edinburgh, EH9 3FB, UK.
Sci Rep. 2025 Jan 13;15(1):1770. doi: 10.1038/s41598-025-86142-4.
Laboratory experiments were performed to investigate the attenuation of progressive deep-water waves by a mono-layer of loose- and close-packed floating spheres. We measured the decay distance of waves having different incident wave frequency and steepness. The attenuation of waves was strong if the surface concentration of particles was close-packed, with the decay distance being shorter for incident waves with higher frequency and steepness. The amplitude of the highest-frequency (2.0 Hz) and largest amplitude incident waves (with steepness 0.25) decayed by half over a distance of approximately 3 wavelengths. Theoretical models used previously in the study of surface wave damping by sea ice do not capture correctly the physics of wave attenuation by floating spheres. We developed a new theory that estimates the influence upon wave attenuation of turbulent dissipation resulting from oscillatory flow under a close-packing of spheres. This theory predicts that the wave amplitude decays as a power law, and gives a correct order-of-magnitude estimate of the observed decay distance. We explore the potential implications of these findings for the attenuation of progressive waves by (pancake) sea ice and for the indirect detection of marine plastic pollution from space.
进行了实验室实验，以研究单层松散和紧密堆积的漂浮球体对深水行进波的衰减作用。我们测量了具有不同入射波频率和陡度的波浪的衰减距离。如果颗粒的表面浓度为紧密堆积，则波浪的衰减很强，对于频率和陡度较高的入射波，衰减距离较短。最高频率（2.0赫兹）和最大振幅（陡度为0.25）的入射波的振幅在大约3个波长的距离内衰减了一半。先前在海冰对表面波阻尼的研究中使用的理论模型没有正确捕捉到漂浮球体对波浪衰减的物理过程。我们开发了一种新理论，该理论估计了在球体紧密堆积情况下振荡流引起的湍流耗散对波浪衰减的影响。该理论预测波幅以幂律形式衰减，并对观测到的衰减距离给出了正确的量级估计。我们探讨了这些发现对于（薄饼状）海冰对行进波的衰减以及从太空间接检测海洋塑料污染的潜在影响。
