重气扩散中复杂障碍物的数值处理方法  

Numerical treatment of complex obstructions in heavy gas diffusion field

作　　者：王正[1] 李向阳[2] 陈杰[2] 赵祥迪[1] 

机构地区：[1]中国石化安全工程研究院,山东青岛266071 [2]中国科学院过程工程研究所,北京100190

出　　处：《计算机与应用化学》2013年第10期1087-1090,共4页Computers and Applied Chemistry

基　　金：国家自然科学基金资助项目(21276004);国家重点基础研究发展计划(2012CB724210);国家高技术研究发展计划(2011AA060704);化学品安全控制国家重点实验室开放课题

摘　　要：CFD方法逐渐成为国内外研究重气扩散物理过程的重要手段。在泄漏源或扩散过程中存在的不同类型的障碍物改变了大气的流动,使扩散过程更为复杂,在模拟过程中对障碍物的处理是获得准确模拟的关键问题之一。本文综述了目前文献中处理复杂障碍物的方法的基本原理,并通过指出各自的优缺点,为自主开发程序进行重气扩散过程CFD模拟的研究者提供参考。商业软件普遍采用的贴体坐标法,该方法实质上是通过特定的变换方法把物理平面上的不规则区域转换成计算平面上的规则区域,原则上是与实际障碍物最接近的处理方法。该方法的缺点在于生成网格过程工作量较大,也会使微分方程和数值方法复杂化,同时自编程序实现难度较大;浸入边界法和镜像流体法类似,都在固定的欧拉坐标系中求解流体运动方程。不同之处在于浸入边界法是把固体界面对流体的作用看作流体在界面所在位置受到的弹性力作用,在流体运动方程中加入一个外力项来描述界面作用在流体上的力。镜像流体法则把固体所占用区域格点上的流体力学参数由镜像关系指定,固体的运动通过拉格朗日方法追踪。这两种方法生成网格过程工作量小,处理流场中复杂固体边界均能获得准确的模拟结果,具有良好的应用前景。近似台阶法原理上最简单也最易实现,但其应用需要进一步改进以提高其精度。CFD method becomes one of the most important means to study the heavy gas dispersion study. The different types of obstacles existing around the source of the leak or in the diffusion field can change the flow of the atmosphere so greatly that the diffusion process is made more complex. Numerical treatment of the obstacles is one of the key issues to obtain accurate simulation. The methods dealing with complex obstacles have been reviewed and their advantages and disadvantages have also been pointed out which can provide a reference for the researchers using in-house program. Body-fitted coordinate method commonly used by commercial software is essentially a transformation from irregular region on the physical plane into regular one on the calculation of plane. This needs a larger workload in generating body-fitted meshes and also makes differential equations and numerical methods complex. The immersed boundary method and the mirror fluid method are similar in solving equations of fluid motion in fixed Eulerian coordinates. The difference is that the action of the solid surface on the fluid is treated as a elastic force and a term to describe this external force is added in the motion equation in immersed boundary method. In the mirror fluid method, hydrodynamic parameters of the locations occupied by the solid points are specified base on the mirror relationship. Then the movement of solids is tracked by Lagrangian hacking. Both methods need small workload in the mesh generation. Accurate simulation results can be obtained when the flow field with complex solid boundary was processed. So, both of them have good applicable potential. The approximation-step method with the simplest principle needs further modification to improve its accuracy.

关 键 词：重气扩散 数值模拟 障碍物 

分 类 号：X169[环境科学与工程—环境科学] X937