Dynamics of gas exchange across the air-water interface: Insights from PIV and LIF measurements

Understanding the mechanism of gas exchange across the air-water interface is crucial for improving prediction models of the global carbon cycle, climate change dynamics, and weather patterns. To contribute to this understanding, we conducted a series of simultaneous PIV/LIF experiments in an air-water channel. PIV was used for water velocity fields, oxygen LIF for capturing spatial and temporal dissolved oxygen data, and surface LIF for observing air-water interface deformation. The channel measures 1300 mm in length, 600 mm in width, and 106 mm in height, filled with water up to 50 mm. It is placed at the end of an air channel, allowing the inlet air to develop over 108 channel heights. The inlet air turbulence is quantified using a hot-wire before interacting with the water surface. Preliminary results indicate that increasing air velocity enhances the deformation of the air-water interface and the rate of oxygen dissolution. Furthermore, fluctuating velocity and vorticity components are high near the interface due to the wind-driven shear. Additional findings on the instantaneous structures of dissolved oxygen, the rate of oxygen dissolution, and the turbulence state of both air and water for different air velocities will be presented at the conference.