Discrete element method modeling of granular flow characteristics transition in mixed flow
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Discrete element method modeling of granular flow characteristics transition in mixed flow Yong Feng1 · Ziran Yuan1 Received: 12 July 2019 / Revised: 25 October 2019 / Accepted: 22 December 2019 © OWZ 2020
Abstract The silos have a complex flow behavior: The lower part presents a “funnel flow” and the upper part presents a “mass flow”. It is necessary to study the flow characteristics of the silos in mixed flow on mesoscale. In this paper, the change in flow characteristics was analyzed in terms of the velocity and angular velocity, to clarify the special effect of the flow pattern transition and time variation during discharge. The results show that the flow characteristics change significantly during the flow pattern transition, the flow characteristics would not variety uniformly with height, and the flow pattern and shear zone have a great influence on them: the flow characteristics change more dramatically in funnel flow; the particles in the shear zone move slowly and rotate sharply with friction couples. The flow transformation can be characterized by more flow characteristics, not only the vertical velocity. Moreover, the profiles of velocity and angular velocity almost would not evolve with time, but only with the particles’ position. The study on the distribution and dynamic evolution of flow characteristics in silos provides theoretical basis for structural optimization design of self-weight discharge silos. Keywords Discrete element method · Flow pattern · Silo · Flow characteristics
1 Introduction Silos with hoppers are container structures that are used in industries. Flow of granular materials in silos is important in many process engineering applications such as food, agricultural, and powder industries [1, 2]. The flow behaviors of these granular materials are generally difficult to be predicted on account of the complex properties of granular materials. The cost of experimental tests sometimes makes it unaffordable for the engineering; the numerical simulation like DEM (discrete element method) [3] and the finite element method (FEM) [4, 5] have been used widely in last decade for understanding the flow behavior of silos. Since CUNDALL put forward the PFC, EDEM, DEMMT, and other numerical simulation software based on the discrete element method have been widely used in the field of granular materials research [6, 7]. DEM (discrete element modeling)
* Ziran Yuan [email protected] 1
College of Civil Engineering, Henan University of Technology, Zhengzhou 450001, Henan, China
software can obtain the mesoscopic parameters of discrete particles [8, 9]. Over the past decade,researchers have been committed to predict the discharge rate [10, 11] and the normal pressure on silo wall [12]. In addition, it is also valuable to explore the influence of physical parameters on flow pattern [13] and the mechanism of jamming during discharge [14, 15]. Previous researches have achieved remarkable results: The flow pattern in silos can be roughly divided into three types: mass flow, funnel flow, and mixed fl
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