Bubble Effects on Wall Shear in Vortical Flows

Direct numerical simulations of the motion of bubbles in turbulent flows are being carried out, using a finite volume/front tracking technique that accounts fully for the effect of fluid inertia, viscosity, bubble deformability, and surface tension. The objective of the simulations is both to address the fundamental interaction mechanisms between the bubbles and the flow and how the bubbles modify the wall turbulent structures, as well as to provide data for validation of simplified models. Results for bubbles placed in the so-called “minimum turbulent channel” show significant drag reduction as the bubbles disrupt the near-wall turbulent flow.