Effect of Micro-bubbles on a Turbulent Boundary Layer

Micro-bubble is one of the most promising methods for reduction of skin friction drag. The injection of gas bubbles into a turbulent boundary layer may have multiple impacts on the turbulent flow structure. This work aims to understand the interaction between micro-bubbles and the turbulent boundary layer, especially the effect of the bubble layer thickness on the skin-friction drag reduction. Large eddy simulation was conducted for a turbulent boundary layer over a flat plate, injected with micro-bubbles, with a view to reduce skin-friction drag. The Reynolds number Re _θ examined was 1430 based on the momentum thickness θ and free-stream velocity \( U_{\infty } \). A three-dimensional perturbation method was deployed to generate a turbulent boundary layer within a short distance of inflow.