Direct numerical simulation of wall turbulent flows with microbubbles

The marker-density-function (MDF) method has been developed to conduct dire ct numerical simulation (DNS) for bubbly flows. The method is applied to tu rbulent bubbly channel flows to elucidate the interaction between bubbles a nd wall turbulence. The simulation is designed to clarify the structure of the turbulent boundary layer containing microbubbles and the mechanism of f rictional drag reduction. It is deduced from the numerical tests that the i nteraction between bubbles and wall turbulence depends on the Weber and Fro ude numbers. The reduction of the frictional resistance on the wall is atta ined and its mechanism is explained from the modulation of the three-dimens ional structure of the turbulent flow. Copyright (C) 2001 John Wiley & Sons , Ltd.