基于局部本构理论的三维筒仓卸载问题研究

Study of the Discharge Flow of Granular Media from a Three Dimensional Silo Based on the Local Constitutive Law

研究颗粒流的运动规律对核安全学科有重要意义,目前颗粒流的数值模拟方法主要是离散元法,该方法的弊端是计算速度慢。近年来,通过对大量实验和离散元模拟结果进行无量纲分析后,科学家得出了颗粒物质的本构理论,本质上是将颗粒物质看成带有摩擦性质的非牛顿流体。该方法与离散元方法相比能够大大降低运算时间,本文主要研究基于上述本构理论的三维计算在筒仓卸载构型中的适用性。结果表明,出口为矩形情况下,类似二维筒仓(quasi 2D)和二维(2D)筒仓卸载出口流量完全吻合,该三维计算模型得到了验证,且流量满足二维Beverloo关系式。另外,出口为圆形的情况下,流量满足三维Beverloo关系式,证明了该局部本构理论在筒仓卸载三维构型中仍适用。

The study of the motion of granular flow is important for nuclear safety.The current simulation method to study granular flow is mainly discrete element simulation.The computational cost of this discrete element method simulation is high.In recent years,by conducting a dimensionless analysis of a large number of experiments and discrete element simulation results,scientists have derived the constitutive law of granular matter,which essentially treats the granular matter as a non-Newtonian fluid with frictional properties.Comparing with the discrete element method,this constitutive law can greatly reduce the calculation time.This work studies the applicability of the three-dimensional simulation based on the constitutive law in the configuration of the discharge of silo.The results show that when the outlet is rectangular,the discharge flow rate of a quasi two-dimensional silo and a real two-dimensional silo are completely consistent.Thus,the three-dimensional simulation model has been verified.And the two-dimensional Beverloo law has been recovered.In addition,when the outlet is circular,the three-dimensional Beverloo law has also been recovered.This demonstrates the applicability of the local constitutive law in the three-dimensional configuration of silo discharge.