Particle motion in stratified turbulent flows

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The interaction between inertial particles and turbulence is of fundamental importance in many environmental and engineering flows. Most previous studies on the topic have considered the simplified case of inertial particle motion in homogeneous isotropic turbulence. However, little is known about the behavior of inertial particles in stratified turbulence, despite its importance in natural and technologically relevant flows such as cloud formation, motion of plankton, air pollution meteorology, etc.The present proposal is intended for a research stay at Duke University, Durham, North Carolina in the group of Prof. Bragg who combines various novel theoretical methods with corresponding numerical simulations to investigate inertial particle motion in turbulence. The goal of the stay is to explore in detail the motion of inertial particles in stratified turbulence. More specifically, the research proposal incorporates three major objectives to be investigated. First, a systematic study using Direct Numerical Simulation (DNS) is intended to explore the effects of fluid stratification on the transport and mixing of inertial particles in turbulence. Second, turbulence generation due to particle clustering (i.e. production of fluid kinetic energy results from momentum coupling with particles) will be quantified by the various terms of the Reynolds-stress budget evaluated by DNS data. The generated results can then advance the turbulence model development considering cluster-induced turbulence. The third objective is to use the dispersion theory and DNS data to develop a simplified turbulent dispersion model to predict particle motion in stratified turbulence that can be used for engineering large-scale calculations. In addition to the technical goals, this research stay will bridge the established research groups dealing with DNS and modeling and build up a scientific network between Europe and USA.