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An Isaac Newton Institute Workshop

Developments in Experimental Pattern Formation

Pattern formation in dense granular flow on an inclined plane

Author: Robert Ecke (Los Alamos)


Experimental results are presented for the periodic patterns formed in flowing granular media on a rough planar surface that was steeply inclined at 41.3$^\circ$ with respect to horizontal. The surface height profile was measured using laser deflection and the velocity field was determined simultaneously using particle image velocimetry. We demonstrate that the structure of the local flow making up the stripes has height maxima for fast flowing regions, that the amplitude of the pattern evolves over downstream length scales that are 50-100 times the lateral wave length, and that the thickness at which the flow becomes unstable to the formation of lateral stripes is quite close to the thickness at which the flow does not have an average terminal velocity.