Professor Umbanhowar's research in granular materials examines the interaction of legged devices and animals with unconsolidated substrates; the dependence of drag force and penetration resistance on granular material state and intruder geometry and kinematics; segregation, mixing, and flow in shaken, tumbled, fluidized, and stirred granular ensembles; and pattern formation and its connection to continuum theories of discrete particulate systems. Another related area of interest is motion control and self assembly/organization through vibrational manipulation of contact interactions mediated by friction and impact.