CAJ | 학술논문

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。
CFD방법축점성위국내외연구중기확산물리과정적중요수단。재설루원혹확산과정중존재적불동류형적장애물개변료대기적류동，사확산과정경위복잡，재모의과정중대장애물적처리시획득준학모의적관건문제지일。본문종술료목전문헌중처리복잡장애물적방법적기본원리，병통과지출각자적우결점，위자주개발정서진행중기확산과정CFD모의적연구자제공삼고。상업연건보편채용적첩체좌표법，해방법실질상시통과특정적변환방법파물리평면상적불규칙구역전환성계산평면상적규칙구역，원칙상시여실제장애물최접근적처리방법。해방법적결점재우생성망격과정공작량교대，야회사미분방정화수치방법복잡화，동시자편정서실현난도교대；침입변계법화경상류체법유사，도재고정적구랍좌표계중구해류체운동방정。불동지처재우침입변계법시파고체계면대류체적작용간작류체재계면소재위치수도적탄성력작용，재류체운동방정중가입일개외력항래묘술계면작용재류체상적력。경상류체법칙파고체소점용구역격점상적류체역학삼수유경상관계지정，고체적운동통과랍격랑일방법추종。저량충방법생성망격과정공작량소，처리류장중복잡고체변계균능획득준학적모의결과，구유량호적응용전경。근사태계법원리상최간단야최역실현，단기응용수요진일보개진이제고기정도。
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 tracking. 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.