Work

Sub-surface turbulence or non-breaking capillary waves: which dominates air–water gas transfer?

Year: 2025

Type: article

Abstract: We examine the separate effects of turbulence beneath a free surface and non–breaking surface capillary waves on the gas-transfer velocity of atmospheric oxygen into water across an air–water interface. The experiments are conducted in a recirculating open water channel with quiescent air, where atmospheric oxygen naturally dissolves into the water via the exposed surface. Through the combination of an active turbulence grid and an array of surface penetrating dowels, we are able to separate the effects of sub-surface turbulence and surface capillary waves. The findings demonstrate that the gas-transfer velocity trends with the turbulence properties, not the capillary wave properties, thus indicating that, when both are present, it is the sub-surface turbulence, not the capillary waves, that plays the dominant role in determining the rate of gas transfer across an air–water interface in the non-breaking capillary wave regime.

Source: Journal of Fluid Mechanics

DOI: 10.1017/jfm.2025.242

Authors: Leon Li, Pim A. Bullee, Simen Å. Ellingsen, R. Jason Hearst

Institutions: Norwegian University of Science and Technology, ETH Zurich, Institute of Fluid Dynamics

Language: English

Topic: Ocean Waves and Remote Sensing

Subfield: Oceanography

Field: Earth and Planetary Sciences

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $3,550

Funders: European Commission, Norges Forskningsråd, European Research Council