Turbulence anisotropy modulation in bubble-laden channel flow: A numerical study

The effect of buoyant bubbles – undergoing deformation, breakup, and coalescence – on wall-bounded turbulence is explored through numerical simulations of a bubbly channel flow in an upwards configuration. We show that the dispersed phase drastically changes the turbulence intensities. In particular, we demonstrate that while bubbles increase anisotropy in the core region, most of the channel exhibits a higher degree of isotropy compared to the single-phase flow. We attribute this energy redistribution to an increase in sweeps, driven by the turbulent wakes and shear layers generated by the largest bubbles. These findings pave the way for a better understanding of bubble-laden flows and offer valuable data for validating Reynolds stress models.