Defining Temperatures of Granular Powders Analogously with Thermodynamics to Understand the Jamming Phenomena

TL;DR

This paper introduces a novel concept of granular temperature to describe jamming phenomena in powders, aligning granular systems with thermodynamic principles for better understanding and prediction.

Contribution

It defines a new granular temperature analogous to thermal temperature, enabling the application of thermodynamic laws to granular powders and explaining jamming transitions.

Findings

Predicted jamming volume fractions match experimental data.

The new temperature concept explains particle movement and jamming behavior.

Bridges the gap between thermal systems and granular materials.

Abstract

For the purpose of applying laws or principles originated from thermal systems to granular athermal systems, we may need to properly define the critical temperature concept in granular powders. The conventional environmental temperature in thermal systems is too weak to drive movements of particles in granular powders and cannot function as a thermal energy indicator. For maintaining the same functionality as in thermal systems, the temperature in granular powders is defined analogously and uniformly in this article. The newly defined granular temperature is utilized to describe and explain one of the most important phenomena observed in granular powders, the jamming transition, by introducing jamming temperature and jamming volume fraction concepts. The predictions from the equations of the jamming volume fractions for several cases like granular powders under shear or vibration are in line with experimental observations and empirical solutions in powder handlings. The goal of this article is to establish similar concepts in granular powders, allowing granular powders to be described with common laws or principles we are familiar with in thermal systems. Our intention is to build a bridge between thermal systems and granular powders to account for many similarities already found between these two systems.