SIR Physics Investigation Abstract
EXPERIMENTATION WITH GRANULAR MATERIALS
Presenter:
Temi-tope Okubadejo, Illinois Mathematics and Science Academy
Advisor:
Dr. Nick Pohlman, Northwestern University
Abstract:
Granular materials demonstrate a unique de-mixing effect when flowing in heaps or rotating tumblers, which challenge pharmaceutical companies in medicine production. Heaping experiments involve a mixture of two different particle types (size, density, and/ or shape) where the particles are poured between two narrowly spaced vertical plates constructed of two same sized clear plastic sheets, for visibility of poured mixture, and bolted together with two thick plates. Particles that exhibit different angles of repose, size, and shape result in striations, while those of similar shape but different size produce segregation. Striations are characterized by repeated horizontal layers of larger and small particles where as segregation is the separation of particles in singular areas.
Rotating tumblers generate a continuous flow of the granular materials. A mixture half of the total volume of a two dimensional shape, is rotated on a machine capable of controlling the rotational speed, and inversely how well the particles separate. Results indicate that a circular shaped tumbler produces a pattern similar to a semi-circular shape while squares produce unique patterns of larger particles in the corners and smaller particle more near the middle of the sides and the center of the shape.