Jeff is internationally known and respected in suspension mechanics and has a broad and deep understanding of the mechanics of fluid-particle systems. His explanations include experimental and theoretical insights. He's published widely and participated in major leadership roles in the field, including programs in fluid mechanics for the AIChE and chairing the Bingham Award Committee for Society of Rheology. Jeff is an acknowledged leader worldwide on fluid-particle systems, widely recognized for his theoretical contributions as well as using numerical simulations to address challenging problems in suspension mechanics. In his own group and collaboration, Jeff has produced results on phenomena in suspension flows and new experimental approaches for these problems. Jeff's major contributions to the rheology of suspensions include theory-simulations based on single-particle insights as well as modeling with effective medium approaches. He studies the rheology of Brownian and non-Brownian suspensions and studied unusual fluid-particle systems such as interfaces, commonly used for the stabilization of multiphase materials. Jeff’s new ideas, including accounting for finite volume fractions and inertial effects, have been tested using numerical simulations and experiments. He reviews the progress in the field and applies the results to more practical situations: suspension flow in thin films and suspension jet flow.