Spontaneous jamming and unjamming in a hopper with multiple exit orifices

Area of Science:

• Physics
• Engineering
• Materials Science

Background:

• Granular material flow through hoppers is crucial in various industries.
• Hopper flow is often characterized by intermittent jamming and unjamming phenomena.
• Understanding factors influencing flow rate is essential for process optimization.

Purpose of the Study:

• To investigate the impact of multiple exit orifices on granular material flow in a 2D hopper.
• To quantify the effect of interorifice distance on total flow rate and jamming behavior.
• To elucidate the mechanisms driving jamming and unjamming events with multiple exits.

Main Methods:

• Utilized discrete element simulations (DES) to model granular flow.
• Simulated a two-dimensional flat-bottomed hopper with varying numbers and spacings of exit orifices.
• Analyzed flow patterns, avalanche sizes, and jamming/unjamming dynamics.

Main Results:

• Multiple exits significantly alter granular flow compared to single exits.
• Interorifice distance critically affects the total amount of granular material flow (avalanche size), enabling up to tenfold enhancement.
• Observed a sequence of jamming and unjamming events, where flow through one orifice can trigger resumption in adjacent jammed orifices.
• Flow unjamming is driven by fluctuations alone at large interorifice distances, but by both fluctuations and mean flow when orifices are closely spaced.

Conclusions:

• The configuration of multiple exit orifices offers a powerful method to control and enhance granular material flow.
• Adjusting interorifice distance is a key parameter for optimizing hopper discharge and preventing blockages.
• The interplay between fluctuations and mean flow dynamics dictates the unjamming process in multi-orifice hoppers.