Bubble-mediated gas transfer of dilute gas in homogeneous and isotropic turbulent flow *

Gas exchange from bubbles in turbulent flow is critical in bubble column chemical reactors as well as for the ocean-atmosphere interface where the air is entrained by breaking waves. Understanding the transfer rate from a single bubble in turbulence at large Péclet numbers (defined as the ratio between the rate of advection and diffusion of gas) regimes is important as it can be used for improving the models on a larger scale. We study the mass transfer of dilute gases from a single bubble in a homogeneous isotropic turbulent flow in the limit of negligible bubble volume variations. We show that the mass transfer occurs within a thin diffusive boundary layer at the bubble-liquid interface, whose thickness decreases with an increase in turbulent Péclet number, Pe. We present a model for exchange velocity that is verified by direct numerical simulations of mass transfer of dilute gas having up to Schmidt number, Sc = 100 from a bubble in homogeneous and isotropic turbulence in region 50 < Pe < 10⁴. The direct numerical simulations are performed with an efficient wavelet-based adaptive mesh refinement resolving the thin boundary layers for high Schmidt numbers along with Kolmogorov and Batchelor scales (Farsoiya et. al. 2021).