Related Experiment Video
Updated: Dec 12, 2025

Fabrication, Operation and Flow Visualization in Surface-acoustic-wave-driven Acoustic-counterflow Microfluidics
Published on: August 27, 2013
Intermittent flow and transient congestions of soft spheres passing narrow orifices
Kirsten Harth1, Jing Wang, Tamás Börzsönyi
1Institute of Physics, Otto von Guericke University, Department of Nonlinear Phenomena, Universitätsplatz 2, D-39106 Magdeburg, Germany. ralf.stannarius@ovgu.de.
Abstract:
Soft, low-friction particles in silos show peculiar features during their discharge. The outflow velocity and the clogging probability both depend upon the momentary silo fill height, in sharp contrast to silos filled with hard particles. The reason is the fill-height dependence of the pressure at the orifice. We study the statistics of silo discharge of soft hydrogel spheres. The outflow is found to become increasingly fluctuating and even intermittent with decreasing orifice size, and with decreasing fill height. In orifices narrower than two particle diameters, outflow can stop completely, but in contrast to clogs formed by rigid particles, these congestions may dissolve spontaneously. We analyze such non-permanent congestions and attribute them to slow reorganization processes in the container, caused by viscoelasticity of the material.
Related Concept Videos
Steady Flow of a Fluid Stream
During this process, the momentum of the fluid within the control volume remains constant over the time interval dt. By applying the...
Steady, Laminar Flow in Circular Tubes
Laminar and Turbulent Flow
Gradually Varying Flow
Rapidly Varying Flow
Design Example: Flow of Oil Through Circular Pipes

