John F. Brady

Fluid dynamics specialist in area of "complex fluids." Developed, with Bossis, a molecular-dynamics-like method for modeling micro-structural and macroscopic properties of complex fluids in presence of shear. Developed scaling theory for diffusive and rheological behavior of concentrated colloidal dispersions by showing how the most important effects of hydrodynamics can be included by a simple rescaling of time or shear rate by concentration dependent self-diffusivity. Devised the suspension balance model, to serve as a constitutive equation for macroscopic description of the flow of concentrated suspensions, which can account for all the unusual rheological properties that have been observed experimentally for such systems. Turned his focus to "microrheology" and in a series of papers with Squires and others, showed what is measured in a colloidal probe, and how to extend "passive" microrheology, in which a probe's motion is caused by thermal fluctuations and is therefore limited to probing a material's linear-response behavior, to "active" and nonlinear microrheology.  Discovered the swim pressure -- a new contribution to the stress in all active matter owing to its random motion.