Title: Modified kinetic theory applied to the shear flows of granular materials

Abstract

Here, granular materials are characterized by large collections of discrete particles, where the particle-particle interactions are significantly more important than the particle-fluid interactions. The current kinetic theory captures fairly accurately the granular flow behavior in the dilute case, when only binary interactions are significant, but is not accurate at all in the dense flow regime, where multi-particle interactions and contacts must be modeled. To improve the kinetic theory results for granular flows in the dense flow regime, we propose a Modified Kinetic Theory (MKT) model that utilizes the contact duration or cut-off time to account for the complex particle-particle interactions in the dense regime. The contact duration model, also called TC model, is originally proposed by Luding and McNamara to solve the inelastic collapse issue existing in the Inelastic Hard Sphere (IHS) model. This model defines a cut-off time t_c such that dissipation is not counted if the time between two consecutive contacts is less than t_c. As shown in their study, the use of a cut-off time t_c can also reduce the dissipation during multi-particle contacts. In this paper we relate the TC model with the Discrete Element Method (DEM) by choosing the cut-off time t_c to be themore » duration of contact calculated from the linear-spring-dashpot soft-sphere model of the DEM. We examine two types of granular flows: simple shear flow and the plane shear flow, and compare the results of the classical Kinetic Theory (KT) model, the present MKT model, and the DEM model. Here, we show that the MKT model entails a significant improvement over the KT model for simple shear flows at inertial regimes. With the MKT model the calculations are close to the DEM results at solid fractions as high as 0.57. Even for the plane shear flows, where shear rate and solid fraction are inhomogeneous, the results of the MKT model agree very well with the DEM results.« less

Authors:

Duan, Yifei ^[1]; Feng, Zhi -Gang ^[1]; Michaelides, Efstathios E. ^[2]; Mao, Shaolin ^[3]

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+ Show Author Affiliations

1. Univ. of Texas at San Antonio, San Antonio, TX (United States)
2. Texas Christian Univ., Fort Worth, TX (United States)
3. Univ. of Texas at El Paso, El Paso, TX (United States)

Publication Date:

Tue Apr 11 00:00:00 EDT 2017

Research Org.:

Univ. of Texas at San Antonio, San Antonio, TX (United States)

Sponsoring Org.:

USDOE Office of Fossil Energy (FE)

OSTI Identifier:

1347615

Alternate Identifier(s):

OSTI ID: 1361806

Grant/Contract Number:  

FE0011453

Resource Type:

Accepted Manuscript

Journal Name:

Physics of Fluids

Additional Journal Information:

Journal Volume: 29; Journal Issue: 4; Journal ID: ISSN 1070-6631

Publisher:

American Institute of Physics

Country of Publication:

United States

Language:

English

Subject:

36 MATERIALS SCIENCE; kinetic theory; granular flows modeling; discrete element method