title: Experimental observation of negative effective gravity in water waves.
abstract: The gravity of Earth is responsible for the formation of water waves and usually difficult to change. Although negative effective gravity was recently predicted theoretically in water waves, it has not yet been observed in experiments and remains a mathematical curiosity which is difficult to understand. Here we experimentally demonstrate that close to the resonant frequency of purposely-designed resonating units, negative effective gravity can occur for water waves passing through an array of resonators composing of bottom-mounted split tubes, resulting in the prohibition of water wave propagation. It is found that when negative gravity occurs, the averaged displacement of water surface in a unit cell of the array has a phase difference of π to that along the boundary of the unit cell, consistent with theoretical predictions. Our results provide a mechanism to block water waves and may find applications in wave energy conversion and coastal protection.
authors.affiliation: Department of Materials Science, Key Laboratory of Micro- and Nano-Photonic Structures (Ministry of Education) and Laboratory of Advanced Materials, Fudan University, Shanghai, China. huxh@fudan.edu.cn
authors.forename: Xinhua
authors.initials: X
authors.lastname: Hu
authors.forename: Jiong
authors.initials: J
authors.lastname: Yang
authors.forename: Jian
authors.initials: J
authors.lastname: Zi
authors.forename: C T
authors.initials: CT
authors.lastname: Chan
authors.forename: Kai-Ming
authors.initials: KM
authors.lastname: Ho
mesh_terms: D003198:Computer Simulation; D006112:Gravitation; D013499:Surface Properties; D014867:Water / Q000737:chemistry*; D014872:Water Movements
chemical_list: D014867:Water