Granular Shear Instabilities: Oscillations, Waves and Rolls?

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AbstractCTS-0070591T. Shinbrot and B.J. Glasser, Rutgers University - New BrunswickIt is proposed to investigate the flow microstructure and instabilities in rapid flow of two particle streams past a splitter plate. This is a simple flow geometry where fundamental aspects can be studied, such as the type of instability, typical velocity and vorticity flow structures, the shape of the interface among streams, dimensionless numbers governing the transition, and the role of interparticle stick-slip phenomenon on instabilities. The research was triggered by observations made on a small-scale experiment where unexpected indications of Kelvin-Helmholtz type instabilities have been noticed. The main experiment is based on flow visualization of a quasi-two-dimensional flow using colored and tracer particles at the confluence of two particulate streams. The effect of particle size on various shear flow patterns, including collective behavior of particle motion in large vortices and rollers, will be experimentally determined. This exploratory research aims to establish the flow pattern in a relatively simple shear flow and to derive conclusions for the basic flow mechanisms in particle systems of various particle sizes from micron to nanosize.If successful, this proof of concept projects may have applications in mixing, in chemical and pharmaceutical processing industry, in polymer and ceramics processing.