Large-Eddy Simulation of two-phase boundary layers

Large-Eddy Simulation (LES) is a technique widely spreaded in CFD methodology, known to have an optimal trade-off between computational effort and quality of data. Since complex phenomena may require too much time to be analyzed in detail with Direct Numerical Simulation (DNS), it is important to have a good correlation between DNS and LES in order to scaling simulations to higher Reynolds numbers without sacrificing physical accuracy. This study investigates wind-wave interaction, a complex coupling between turbulent airflow and water surfaces. By isolating the dynamics as a function of the wind's friction Reynolds number, the model provides a fundamental characterization of the problem. An implicit LES was developed to simulate turbulent wind blowing over a water layer initially at rest, with DNS results serving as a benchmark. Despite the idealized nature of the setup, the LES successfully captured key physical features, including oblique wave patterns and the wave-induced Stokes sublayer. While the LES naturally resolved larger turbulent scales than the DNS, the turbulent kinetic energy (TKE) budgets and correlation data demonstrate high similarity. These findings validate the LES approach as a reliable, cost-effective tool for studying wind-wave dynamics at higher Reynolds numbers.