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Research Interests:
My research interests include agglomeration and deagglomeration, static granular packings, and granular flows.
Research Summary:
Presently, I am working to understand the mechanics of wetted granular particles. This research has applications to granulation, filtration, coagulation, spray coating, drying, and pneumatic transport. Wetted particles are relevant in many industries including the pharmaceutical and chemical industries. Significant contribution to this research area has already been made. Namely two-particle collisions (particle-wall and particle-particle) for wetted and fully immersed particles have been investigated theoretically, experimentally, and computationally. The focus of our current project is to extend existing theory and experiments to three particle collisions. A Newton's Cradle is used, which for the case of wetted particles we call a “Stokes Cradle”. We are currently in the process of using the apparatus to verify the existing theory for two particle collisions. Afterwards we will move on the create an experimental regime map for the three particle collinear collisions to compare against developing theory.
To extend the theory to three particle collisions, we are first considering a “toy” model in which the collisions are assumed to be a series of two particle collisions. This method works well for the traditional Newton’s cradle which involves collisions of dry particles. Using a Matlab program, I have created a regime map for various dimensionless parameters has been created, depending on Stokes number, Stokes critical number and the coefficient of restitution of the dry particle. The next step is to work out the more rigorous lubrication and Hertzian equations for three-particle contacts. The ability of the simplified model to predict outcomes will be assessed via comparison with experiments over a part of the parameter range (high restitution coefficient), and via comparison with the more rigorous three-particle theory over that part of the parameter space which cannot be reached experimentally. In the medium term, it will be required to study three-particle oblique collisions. What makes this specifically challenging is that oblique collisions can result in a rotating doublet, which can be pulled apart my centripetal forces not present in collinear collisions. In the long term, we will take what we have learned from macroscopic collisions and apply it to a large system of microscopic particles through molecular dynamics simulations in order to make the connection between microscopic (particle-level) and macroscopic behavior.
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