Dr. John Brady

D.B. Robinson Distinguished Speaker Series 2013-2014

ICI Lecture Part 1:

The Micromechanics of Colloidal Dispersions


It's morning. You pour cereal in your bowl. Shake the orange juice and fill your glass. And pour milk over your cereal. Why did you shake the orange juice and not the milk? Why do you pour cereal? These are just some everyday examples of complex fluids – materials that often behave like water or air, but just as often display quite different behavior. Many soft materials, or complex fluids, are in the form of particles dispersed in a host liquid or gas, and it is the particle-level interactions that give rise to interesting macroscopic phenomena, such as shear thinning and thickening, viscoelasticity and structure formation.

This talk will discuss the micromechanics of particulate dispersions and how the interplay of colloidal, Brownian and hydrodynamic forces set the material’s microstructure and determine its macroscopic properties. Examples of hard-sphere systems ranging in size from a few nanometers, where Brownian motion is important, to larger sand-grain-size mixtures will be investigated via computer simulation and the results compared with theory and experiment. So why did you shake the orange juice and not the milk?

Download a copy of his presentation here (10.8 MB).


John F. Brady is the Chevron Professor of Chemical Engineering and Professor of Mechanical Engineering at the California Institute of Technology. He received his BS in chemical engineering from the University of Pennsylvania in 1975, which was followed by a year at Cambridge University as a Churchill Scholar. He received both an MS and PhD in chemical engineering from Stanford University, the latter in 1981. Following a postdoctoral year in Paris at ESPCI, he joined the Chemical Engineering department at MIT. Dr. Brady moved to Caltech in 1985.

Dr. Brady’s research interests are in the mechanical and transport properties of two-phase materials, especially complex fluids such as biological liquids, colloid dispersions, suspensions, porous media, etc. His research combines statistical and continuum mechanics to understand how macroscopic behavior emerges from microscale physics. He is the co-inventor of the Stokesian Dynamics technique for simulating the behavior of particles dispersed in a viscous fluid under a wide range of conditions.

Dr. Brady has been recognized for his work by several awards, including a Presidential Young Investigator Award, the Professional Progress Award of the American Institute of Chemical Engineers, the Bingham Medal of the Society of Rheology and the Fluid Dynamics Prize of the American Physical Society, Division of Fluid Dynamics. Dr. Brady served as an associate editor of the Journal of Fluid Mechanics and editor of the Journal of Rheology. He is a fellow of the American Physical Society and a member of the National Academy of Engineering.

Dr. John F. Brady

Dr. John F. Brady

Professor of Chemical Engineering

California Institute of Technology, USA
Email: jfb@cheme.caltech.edu
Research Group: JFB Group Stokesian Synamics

Date and time:

(Thursday) September 19, 2013 at 3:30pm


Engineering Teaching and Learning Complex (ETLC) 1-00


Dr. Stevan Dubljevic