Start
Apr 17, 2015 - 10:00
End
Apr 17, 2015 - 11:00
Venue
Room 240 Computer Lab Chemical Engineering
Event Type
Speaker
Prof. Prabhu R. Nott Department of Chemical Enginering Indian Institute of Science Bangalore
Title
Kinematics and stress in flowing granular materials: lessons for constitutive modelling
Asbtract: The mechanics of granular materials (sand food grains powders) has historically been studied in the limiting regimes of slow and rapid flow. In the former the grains are densely packed and stress is transmitted by sustained grain contacts. In the latter regime grains are in continuous fluctuational motion and stress is generated from the impulse transmitted during the brief grain collisions. In recent years it has become evident that there is a vast regime of “intermediate flow” that lies between the above extremes wherein the micromechanics and statistics of grain interaction is not clearly understood. In this presentation I will highlight some of the peculiarities of the kinematics and rheology of granular flows in the slow and intermediate regimes. I will motivate the use of protocols of fluid rheometry for granular materials and address the complexities that arise when doing so. I will discuss the existing continuum models for dense granular flows and point out their deficiencies. I will then discuss some recent experimental results from my group in granular rheometry and show how particle dynamics computations has helped resolve a major puzzle. I will then close with some thoughts on the improvements needed for effective continuum mechanical modelling of granular materials and how particle dynamics computations may be used for critical evaluation and refinement of proposed models.