Turbulence Modulation by Micro-Particles in Boundary Layers

Turbulent dispersed flows over boundary layers are crucial in a number of industrial and environmental applications. In most applications, the key information is the spatial distribution of inertial particles, which is known to be highly non-homogeneous and may exhibit a complex pattern driven by the structures of the turbulent flow field. Theoretical and experimental evidence shows that fluid motions in turbulent boundary layers are intermittent and have a strongly organized and coherent nature represented by the large scale structures. These structures control the transport of the dispersed species in such a way that the overall distribution will resemble not at all those given by methods in which these motions are ignored.

In this paper, we study from a statistical viewpoint turbulence modulation produced by different-size dispersed particles and we examine how near-wall particle concentration is modified due to the action of particles themselves in modulating turbulence. The physical mechanisms and the statistics proposed are based on Direct Numerical Simulation (DNS) of turbulence and Lagrangian particle tracking, considering a two-way coupling between particles and fluid.