Larson is an expert in the theory and simulations of
rheology,
fluid mechanics, and
transport phenomena. His research contributions are in self-assembling
soft matter, especially
polymers,
colloids,
surfactant-containing fluids,
liquid crystalline polymers, biological
macromolecules such as DNA, proteins, and
polyelectrolytes. Larson (along with
Susan Muller at
UC Berkeley and
Eric Shaqfeh at
Stanford) is known for the discovery of fluid mechanical
instabilities of polymeric fluids in curved streamlines due to polymer stretching. These types of streamlines, commonly found in
Taylor-Couette flows, are of great importance to the polymer processing industry. Analogous instabilities have been known for over a century for ordinary fluids such as air and water, and these instabilities drive common phenomena such as
weather patterns, as well as
vortices and other phenomena in common industrial flows of liquids. He has developed molecular
constitutive equations for entangled polymers, as well as many predictive theories for nonlinear rheology of branched polymers, polymers unraveling in shear and extensional flows, polymer drag reduction, shear-induced alignment transitions in
block copolymers, slip and cavitation in
polymer solutions and melts, and arrested tumbling of
liquid crystalline polymers. These methods have been used worldwide by researchers to understand and predict the flow properties of polymeric fluids. Larson is the sole author of two textbooks, "Constitutive Equations for Polymer Melts and Solutions", and "The Structure and Rheology of Complex Fluids". He has also co-authored with John Dealy and Daniel Read on the book, "Structure and Rheology of Molten Polymers". According to
Google Scholar, Larson's publications have received over 42,500 citations and his
h-index is 87. == Awards and honors ==