Nonlinear simulation of wave group attenuation due to scattering in broken floe fields

• Published in: Ocean modelling (Oxford) Vol. 181; p. 102139
• Main Authors: Xu, Boyang, Guyenne, Philippe
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.02.2023
• Subjects: Ice floes; Nonlinear waves; Numerical simulations; Sea ice; Wave attenuation; Wave scattering; Nonlinear waves; Numerical simulations; Ice floes; Wave attenuation; Wave scattering; Sea ice
• ISSN: 1463-5003; 1463-5011
• DOI: 10.1016/j.ocemod.2022.102139

Direct phase-resolved simulations are performed to investigate the propagation and scattering of nonlinear ocean waves in fragmented sea ice. The numerical model solves the full time-dependent equations for nonlinear potential flow coupled with a nonlinear thin-plate representation of the ice cover, and it neglects dissipative processes. The two-dimensional setting with incident wave groups on deep water is considered, in view of applications to wave attenuation along transects of the marginal ice zone. A spatially-varying weight is assigned to the surface pressure so that irregular distributions of ice floes can be directly specified in the physical domain. For various wave regimes and floe configurations, a local wave spectrum across the ice field is computed and then least-squares fitted to extract a spatial attenuation rate as a function of wave frequency. A general increase with frequency is found, consistent with typical predictions from linear theory. However, a non-monotonic behavior around a certain frequency is also observed, especially in cases with a highly fragmented ice cover. The key role played by nonlinear interactions in this phenomenon is highlighted. •Phase-resolved simulations of nonlinear ocean waves in fragmented sea ice are performed.•Incident wave groups in the two-dimensional deep-water setting are considered.•Estimates of spatial attenuation rate as a function of wave frequency are obtained.•Comparison with field observations and linear theory is presented.•Roll-over of attenuation rate in cases of a highly fragmented ice cover is observed.