Title:

The Dynamics of Inertial Particles in Turbulence: Role of Density Ratio, Turbulence Scales and Gravity on Preferential Accumulation and Relative Velocity

Abstract:

The dynamics of solid particles, liquid droplets and gas bubbles hold significant gaps in our fundamental understanding, and at the same time, are of great relevance in many industrial and environmental applications. The microphysics of individual particles, as well as of particle clusters, occuring at the smallest scales of the turbulent flow play an important role—sometimes dominant—in phenomena such as formation of rain drops in warm rain, condensation/evaporation of water vapor in hurricans, and gas transfer in bubbles entrained by breaking waves in the ocean.

I will discuss laboratory experiments in which we probe the inertial effects in the dynamics of heavy particles in a homogeneous isotropic turbulent flow. The interaction of the inertial particles with the turbulent vortical structures results in accumulation of droplets in regions of high strain and the modification of the drift velocity of droplets due to gravity. The analysis proposed here is based on measurements of the evolution of smalll inertial particles, at both ends of the density ratio spectrum, in homogenous, isotropic turbulence, as well as in a boundary layer and a turbulent/non-turbulent interface are analyzed to understand the particle concentration field, and the relative velocities.

The dependence of clustering on turbulent characteristics and the parameters controlling the transition between settling velocity enhancement and hindering are among the most important results from this series of studies conducted in different wind tunnels with different types of grid turbulence.

Bio:

Dr. Aliseda is the PACCAR Professor at the University of Washington in Seattle where he has been in the faculty since 2006. He has also served as the chair of the Department of Mechanical Engineering since July 2021. He holds adjunct (courtesy) appointments in Aeronautics and Astronautics and Neurological Surgery. Prior to UW, Aliseda obtained his PhD and conducted postdoctoral research at the University of California, San Diego. Before his graduate studies, he earned a bachelor's and master's degree in Aerospace Engineering from the Polytechnic University of Madrid in 1998. 

His current interests focus on turbulent and multiphase flows, including flows of interest to enegy conversion and environmental problems, such as liquid atomization and cloud microphysics. He also works on biomedical flows, with a special emphasis on the biomechanical basis of cardiovascular disease and the interaction of medical devices with flows in the heart and arteries. He has been a visiting professor at the Universidad Carlos 3 de Madrid, the École Normale Supérieure de Lyon and the Laboratoire des Ecoulements Geophysiques et Industriels (LEGI) of the Université Grenoble-Alpes and the École des Mines de Saint-Étienne.

The Paul M. Rady Department of Mechanical Engineering Distinguished Seminar Series features scholars from a wide range of peer institutions across the country. The events are open to all faculty, staff and students looking to spark their curiosity and learn about high-impact research from some of the world's most prominent experts in mechanical engineering.