Defining temperatures of granular powders analogously with thermodynamics to understand jamming phenomena

• Main Author: Tian Hao
• Format: Article
• Language: English
• Published: AIMS Press 2017-12-01
• Series: AIMS Materials Science
• Subjects: jamming; granular temperatures; thermodynamics; granular powders
• Online Access: http://www.aimspress.com/Materials/article/1768/fulltext.html

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 using kinetic energy connections. 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 equations are mainly for hard sphere systems without frictional forces among particles, but can be easily extended to frictional granular systems with frictional energy term included in. The goal of this article is to lay a foundation for establishing 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.