Clogging-jamming connection in narrow vertical pipes

Area of Science:

• Physics of granular materials
• Fluid dynamics
• Statistical mechanics

Background:

• Granular materials flowing in confined geometries, like pipes, are prone to clogging.
• Silo clogging is a known phenomenon attributed to the formation of stable arches.
• Frictional forces are crucial for the stability of these granular structures.

Purpose of the Study:

• To experimentally investigate the mechanisms of clogging in narrow vertical pipes for granular flow.
• To explore the relationship between pipe-to-particle diameter ratio and clogging probability.
• To determine the connection between granular clogging in pipes and jamming phenomena.

Main Methods:

• Experimental observation of granular flow and clogging in narrow vertical pipes using spherical particles.
• Analysis of particle ordering and arch formation.
• Numerical simulations to study interparticle force distributions.

Main Results:

• Experimental evidence of clogging caused by spontaneous hanging arches, similar to silo clogging.
• Clogging probability in narrow tubes does not monotonically decrease with increasing pipe-to-particle diameter ratio.
• Particle ordering in specific aspect ratios can prevent clogging.
• Numerical simulations show broader interparticle normal force distributions in systems with higher clogging probability.

Conclusions:

• Frictional forces are essential for the development of stable hanging arches that cause pipe clogging.
• The non-monotonic dependence of clogging on the diameter ratio is linked to spontaneous particle ordering.
• Broader interparticle force distributions suggest a fundamental connection between granular clogging in pipes and jamming.