GRANULAR FLOWS 
GOAL The particles

The idea is to understand the influence of forcing signals in the pattern forming granular structures (convection rolls) when we vertically vibrate a nearly 2D hopper filled with small particles (glass beads). The figure shows snapshots of two type of particles. Small glass beads (d=0.34 mm) and lightweight poppy seeds (d=1.0 mm) used as high contrast big tracers. 
particles 


SETUP
 Vertically vibrated hopper
The experimental setup is simple. A B&K shaker produce a periodic vertical forcing of a nearly 2D hopper, filled with particles, which has a bottom discharge hole and a small container to capture the particle mass flow. We are able to measure the mass flowrate under the hopper during the forcing cycle. As the same time, with a PIV system we can estimate the granular velocity and perform tracking of individual large (black) particles driven by the convection motion of the smaller ones.
 setup hooper

RESULTS
 Granular convection 

A layer of big black particles at the begining of the forcing cycle is progressively convected by the action of the granular flow of small particles (white). Interesting mixing effects are observed. The mass flow rate depends on the forcing frequency and amplitude.

 convection
Cl vs Taylor number



uch
 Universidad de Chile, Facultad de Ciencias Físicas y Matemáticas
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