Dense inclined flows: Theory and experiments. Quarterly technical progress report, April 1--June 30, 1995

Rapid, gravity-driven flows of granular materials down inclines pose a challenge to the understanding of solids flow. Even in situations in which the flow is steady and two-dimensional, the details of how momentum and energy are balanced within the flow and at the bottom boundary are not well understood. Thus the authors have undertaken a research program integrating theory, computer simulation, and experiment that will focus on dense entry flows down inclines. The effort involves the development of theory informed by the results of simultaneous computer simulations and the construction, instrumentation, and use of an experimental facility in which the variables necessary to assess the success or failure of the theory can be measured. In the present reporting period, the authors began a series of measurements in the chute facility with a bumpy boundary constructed using random two-dimensional packings of 1 mm glass spheres. At the inclination of 19{degree} and at several gate openings, they measured mass flow rate and mass holdup, as well as granular temperature and collision frequency at the bottom wall of the chute. By recording simultaneously the collisional normal stress at the bottom wall and the mass holdup above it, the experiments revealed that, unlike the flat boundary, only a small fraction of the weight of particles is supported by direct impact. The authors have also completed measurements of the impact properties for several binary collisions of nearly spherical particles used in this and other projects. A table summarizes the data obtained