Direct numerical simulation of wind-driven turbulence and scalar transfer at sheared gas–liquid interfaces

Abstract

A three-dimensional direct numerical simulation is applied to wind-driven turbulence with sheared gas–liquid interface, and turbulence structure in interfacial boundary layers on both gas and liquid sides and scalar transfer mechanism across the gas–liquid interface are investigated. In order to capture the deforming gas–liquid interface, an arbitrary Lagrangian–Eulerian formulation method is employed. The results show that fluid motions are strongly affected by wind waves with ripples on the liquid side. The wind waves and ripples enhance the turbulence on the liquid side. For the present wind speed of several meters per second, the scalar transfer across the sheared wavy gas–liquid interface is mainly controlled by the streamwise vortices related to the downward bursting motions on the liquid side.

Keywords:

• direct numerical simulation
• gas–liquid interface
• wind-driven turbulence
• gas–liquid scalar transfer

Acknowledgements

The authors are grateful to T. Kobayashi for his help in conducting numerical simulations. This research was supported by Ministry of Education, Science, Sports and Culture grant-in-aid (No. 19206023) and Core Research for Evolutional Science and Technology (CREST) Program “Advanced Model Development and Simulations for Disaster Countermeasures” of Japan Science and Technology Agency (JST). This simulation was partially performed by super computer of National Institute for Environmental Studies, Center for Global Environmental Research.