Work

Experimental evidence of transverse modulation and frequency downshift of uniform waves in a long tank

Year: 2025

Type: article

Abstract: We report experiments in a long tank showing that transverse Benjamin–Feir instability of Stokes waves can lead to a significant energy transfer into oscillations across the tank. We observe frequency downshift in the long-term evolution of Stokes waves essentially when significant energy is transferred to narrow-banded transverse modes. Experiments with Stokes waves are often carried out with wavelengths that are not long compared with the width of the tank, permitting transverse instabilities to be excited. With insufficient resolution of measurements across the tank, transfer of energy to transverse modes can be misinterpreted as dissipation. Our experiments suggest that the frequency downshift depends as much on energy-preserving transverse modulations of type I as it does on damping or wave breaking. Broad-banded unstable modulations of type II do not imply downshift.

Source: Journal of Fluid Mechanics

DOI: 10.1017/jfm.2025.10822

Authors: Karsten Trulsen, Carl Trygve Stansberg, Kristian Barstad Dysthe

Institutions: University of Oslo, SINTEF Ocean, University of Bergen

Language: English

Topic: Nonlinear Waves and Solitons

Subfield: Statistical and Nonlinear Physics

Field: Physics and Astronomy

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $3,550