渗流的PFC-CFD耦合细观数值模拟

本文针对饱和多孔介质中渗流特点,在分析渗流连续介质力学模型的基础上,采用描述多孔介质中固相颗粒和液相流体耦合的细观力学模型,其中固相颗粒采用离散元的颗粒流理论(PFC)模拟,液相流体通过求解平均Navier-Stokes方程的计算流体动力学(CFD)技术计算,并利用建议的模型对二维渗流问题进行了模拟验证。数值模拟结果表明,采用PFC-CFD耦合细观力学模型能够描述从低雷诺流到高雷诺流范围很大的流体运动,可以用于多孔介质中的渗流问题分析。

Improved similarity criterion for seepage erosion using mesoscopic coupled PFC–CFD model

Conventional model tests and centrifuge tests are frequently used to investigate seepage erosion. However, the centrifugal test method may not be efficient according to the results of hydraulic conductivity tests and piping erosion tests. The reason why seepage deformation in model tests may deviate from similarity was first discussed in this work. Then, the similarity criterion for seepage deformation in porous media was improved based on the extended Darcy-Brinkman-Forchheimer equation. Finally, the coupled particle flow code–computational fluid dynamics(PFC-CFD) model at the mesoscopic level was proposed to verify the derived similarity criterion. The proposed model maximizes its potential to simulate seepage erosion via the discrete element method and satisfy the similarity criterion by adjusting particle size. The numerical simulations achieved identical results with the prototype, thus indicating that the PFC-CFD model that satisfies the improved similarity criterion can accurately reproduce the processes of seepage erosion at the mesoscopic level.

EAST运行状态下的PFCs烘烤设计与传热分析

对EAST超导托卡马克装置在低温运行状态下的PFCs真空烘烤进行设计,通过对传热过程进行分析、计算和模拟,验证烘烤的可行性和安全性,并给出了三种烘烤温度以供选择。

EAST PFCs气流烘烤设计及流体与传热计算

根据聚变反应对真空度的要求,在EAST超导托卡马克装置中采用气流烘烤技术来实现对PFCs的真空烘烤。对PFCs烘烤进行了原理设计,对介质气体的参数进行了选择,分析并计算了烘烤时PFCs内部气体流动和传热状况,最后给出了模拟结果。

地铁穿越岩溶区地表塌陷特征及微观力学试验研究

武汉地铁穿越区的岩溶地表塌陷问题目前已经成为该市地铁建设中亟待解决的问题,为更好探究武汉地区岩溶地表塌陷特征及机理,开展了以下研究工作:(1)通过可视化的塌陷物理试验,研究了典型地质结构条件下的塌陷特征以及微观力学特征;(2)基于颗粒流PFC软件平台,对武汉地铁穿越区的典型岩溶地质模型塌陷过程进行了数值模拟;(3)以砂层地质结构模型为研究对象,研究了在不同振动频率和振幅条件下土体中孔隙水压力和孔隙率的发展规律,并通过室内实验进行了对比分析。