Particles turbulence interactions in boundary layers - Plenary lecture presented at the 75th Annual GAMM Conference, Dresden/Germany, 22-26 March 2004

urbulent dispersed flows in boundary layers are crucial in a number of industrial and environmental applications. In most applications, the key information is space distribution of particles which is known to be strongly non-homogeneous. Specifically, inertial particles distribute preferentially avoiding strong vortical regions and segregating into straining regions. The vortical boundary layer structures control momentum, mass, heat, and particle transfer. Coherent structures bring particles toward the wall and away from the wall and favour particle segregation in the viscous region giving rise to nonuniform particle distribution profiles which peak close to the wall. The reason for this behavior is particle inertia, which filters the high frequency turbulence fluctuations. The object of this work is to review the current understanding of turbulent boundary layer dynamics and to examine the mechanisms for particle transfer, segregation, and preferential distribution. The physical mechanisms discussed and proposed are based on Direct Numerical Simulations of turbulence and Lagrangian tracking of inertial particles.