[A-CG47] Dynamics of Oceanic and Atmospheric Waves, Vortices, and Circulations

[ACG47-07] Numerical study of turbulence production by nonbreaking surface waves

★Invited Papers

*Yasushi Fujiwara¹ (1.Graduate School of Maritime Sciences, Kobe University)

Keywords:Ocean surface waves, Wave-current interaction, Wave-resolving numerical simulations

Ocean surface waves play a crucial role in generating upper ocean turbulence, which significantly influences sea surface temperature and air-sea interaction. Experimental and numerical studies have demonstrated that, even without breaking, waves can induce turbulence even in the absence of wind, highlighting the importance of mechanisms other than Langmuir circulations. Using a newly developed two-phase numerical model that allows free propagation of interfacial waves without external forcing, we investigate the role of air-water coupling in this process. Our results show that the presence of an air layer above the water enhances turbulence in the upper ocean compared to water-only simulations. Energy budget analysis reveals that significant energy dissipation occurs in the air-side viscous boundary layer, characterized by strong shear. This dissipation amplifies Eulerian streaming at the upper water layer, which intensifies turbulence and produces eddies aligned with the wave propagation direction. These features are consistent with a Craik-Leibovich type wave-averaged simulation, where the Eulerian streaming is driven by the "virtual wave stress" of Longuet-Higgins [1969], with modifications to account for enhanced wave attenuation due to the air-side boundary layer.