离散流

The main work and the originality points of this dissertation could be concluded as the following parts:(1) To analyze systematically the mathematical model of LES of air flow in great space, under the case of isothermal and non-isothermal, as well as the combined action of buoyancy and strain. Some basic problems are studied about the LES application into airflow simulation of great space, such as boundary conditions, spatial difference scheme and time advancing scheme, time step etc., which creates the basis for the LES application to indoor airflow simulation.(2) Both the instantaneous and time averaged flow field of great space with multiple jets under isothermal and non-isothermal cases are explored with large eddy simulation method, and also discussed the dynamic characteristics and the law of fluidflow in the great space.(3) Based on the results of LES of the great space and the Fanger thermal comfort indexes, it is brought forward the concept of the series of dynamic thermal comfort evaluating indexes, which could be divided into thermal comfort index with time averaged properties PD, PPD, PMV, thermal comfort index with instantaneous properties IPD, IPPD, IPMV, and time averaged thermal comfort indexes TAPD, TAPPD, TAPMV, and transient situations time averaged thermal comfort indexes TTAPD, TTAPPD, TTAPMV. The differences among them and the calculation methods are discussed, and the four kinds of indexes are calculated with the thermal comfort index PD as an example.(4) Based on the LES results it is discussed the hot air stratification phenomena in air-conditioned buildings in the case with air supply and return registers on the ceiling and the case on the sidewall. The fundamentals of the hot air stratification are studied and the relations of estimating hot air stratification are brought forward.(5) With the advanced apparatus such as hot wire film anemometer IFA300 and laser particle field anemoscope, corresponding model test and site measurements have been done, which are compared with the simulation results and LES is proved a very promising method in air flow simulation indoor.

本文主要工作既创新点体现在以下几个方面：(1)系统分析了等温、非等温和考虑剪切力与浮升力综合作用的高大空间大涡模拟数学模型，并研究了高大空间大涡模拟在室内气流仿真应用中的一些基本问题，如边界条件、空间离散格式和时间推进格式、时间步长选择等问题，为大涡模拟在室内气流计算中的广泛应用打下了基础；(2)首次用大涡模拟方法研究了高雷诺数下高大空间多射流在等温、非等温情况下的瞬时流场和时均流场分布，并探讨了多射流流场的动态特性和流动规律；(3)基于大涡模拟的动态仿真结果和Fanger的热舒适指标，首次系统地提出了动态热舒适评价指标体系的概念：即基于时间平均参数的热舒适指标PD、PPD、PMV；基于瞬时参数的瞬时热指标IPD、IPPD、IPMV；基于时间平均热舒适指标TAPD、TAPPD、TAPMV；以及沿行动迹线的时间平均热舒适指标TTAPD、TTAPPD、TTAPMV，并分析了四类热舒适指标的差异性和计算方法，还以PD值为例对四类指标分别进行了计算；(4)基于数十种工况下空调房间大涡模拟的结果，研究了空调建筑上送上回和侧送侧回两种情况下热分层现象，并探讨了热分层的基本规律，首次提出了避免热分层现象的判断公式；(5)在暖通空调领域，首次使用IFA300热线风速仪、激光粒子速度场仪等先进设备，完成了与大涡模拟相对应的模型试验，并把实测结果与仿真结果进行了对比，说明LES在室内气流仿真方面是一种很有前景的方法。

The model is applied to numerically analyze the wave field and the coastwise current formed by the breaking of oblique incident wave in the Leadbetter Beach, Santa Barbara, California, USA. In the analysis the Crank-Nicolson scheme is adopted to solve the parabolic mild slope equation and the ADI finite difference scheme is applied to solve the model of wave induced coastwise current.

运用该近岸流方程，对美国Santa Barbara Leadbetter海岸波浪斜向入射所产生的波浪场及波浪破碎所形成的沿岸流进了数值模拟，其中抛物型缓坡模型采用Crank-Nicolson格式进行数值离散，近岸流方程采用ADI差分格式离散。

The main objective of this dissertation was to develop methodologies with capability of engineering application for simulating flow in fractured rock using discontinuum models. The study work includes three parts. In the first part, numerical methodology of three-dimensional discrete fracture network model casing on hybrid BEM-channel was presented, and the technique for improve the model's computing efficiency was also studied. Firstly in this part, computer simulation methodology based on the Baechermodel for generating network of discrete fractures was presented, which includes the follow details: probability distributions of fracture density,orientation, trace length, size, and aperture and estimation of their statistical parameters; stochastic models of fracture network; Monte-Carlo's simulation method; numerical simulation procedure and technicality.

给出了离散裂隙网络模型所依据的基本假定；发展了基于Baecher模型的离散裂隙网络计算机随机生成技术：详细地推导了单裂隙渗流和多裂隙相交网络渗流的边界单元法公式，发展了离散裂隙网络中稳态渗流的边界元数值技术，并且讨论了相关的具体数值技术细节，如角点的处理方法，单元的自动剖分等：描述了混合边界元—管流模拟方法及其数值实现；研究了裂隙网络的简化方法，并针对裂隙网络边界元法的特点提出了一种改进的分块三角分解法。

For instance, the first prize winner-Investigation Study on Urban Traffic Flow Discrete pattern in China submitted by Beijing City Planning Institute analyzes the pattern of urban traffic and proposes a discrete pattern suitable for China.

如，获得一等奖的北京城市设计规划设计院的《我国城市道路车流离散规律初探》研究了我国城市道路交通流的离散规律及其影响因素，提出了适合我国的交通特点的离散系数

For instance, the first prize winner-Investigation Study on Urban Traffic Flow Discrete pattern in China submitted by Beijing City Planning Institute analyzes the pattern of urban traffic and propose s a discrete pattern suitable for China.

如，获得一等奖的北京城市设计规划设计院的《我国城市道路车流离散规律初探》研究了我国城市道路交通流的离散规律及其影响因素，提出了适合我国的交通特点的离散系数

LES cooperated with the second order full extension ETG finite element method is applied to simulate three typical problems concerned with convection heat transfer with sufficient experimental data. By comparing the numerical results with the experimental results, LES is proved to be of better accuracy and stability when it is used to solve the problems concerned with convection heat transfer. The time history of the flow field and temperature field can be reflected better, and abundant information of the fields can be obtained. Furthermore the details of the change in the vortex structure can be captured.

应用大涡模拟与二阶全展开ETG有限元离散格式相结合的方法对具有实验基础的三个典型对流换热问题进行了数值模拟，并将模拟结果与相应的实验结果进行对比，证明了大涡模拟应用于对流换热问题中具有较高的稳定性和精度，能够较好地反映流场和温度场的时变过程，提供丰富的温度场和流场信息，捕捉流场中旋涡结构的变化细节，尤其适合于边界形状复杂的区段内含有大尺度各向异性涡的流动和换热问题的计算。

The generating function method is applied to the study of integrability structure of these finite-dimensional systems, by which it is very convenient to prove the involutivity of integrals of motion.

上面所提到的这些连续的和离散的2+1维可积模型被分解成所导出的常微分方程的Hamiltonian系统或常微分方程的Hamiltonian系统以及辛映射所产生的离散流。

The discrete velocity ordinate method in the kinetic theory of gases is developed and applied to discretize the correspo

借助非定常时间分裂法和无波动无自由参数的NND耗散格式，建立直接求解微观分子速度分布函数的有限差分数值格式；研究并发展可用于离散速度坐标点选取和离散速度空间宏观取矩的高斯─埃尔米特无穷积分方法、等均间隔的牛顿─柯斯复合积分法、以勒让德多项式的根为积分结点的高斯─勒让德数值积分法，并应用于不同马赫数绕流模拟；通过对不同流域一维激波管问题、二维圆柱绕流问题和三维球体绕流的计算研究，并将计算结果与其他途径得到的研究结果诸如DSMC模拟值、N-S解及有关实验数据进行比较分析，创建了一套能有效模拟稀薄流到连续流不同流域气体流动问题简化的统一数值算法研究框架

In this paper,a 3-D numerical simulation model is proposed to simulate and analyze the 3-D flow characteristics of natural spawning sites of Acipenser Sinensis by using N-S and k-ε formulas,the volume of fluid method is also used to simulate the two phase flow,and the finite volume method is used to disperse the calculated area.

将水动力学N-S方程、k-ε紊流数值模型与计算水气两相流的方法VOF相结合，采用控制体积法离散计算区域，建立了葛洲坝下游中华鲟产卵场的三维流场模拟模型。

With the aid of the solution matrix of Lax equation satisfied by the eigenfunctions, elliptic variables are introduced suitably, which give a direct relation between the soliton equation and the resulting compatible ordinary differential equations.

文中发展了一个分离技术，由此可将连续的和离散的2+1维孤子方程分解为相容的常微分方程或相容的常微分方程和离散流的演化。

The split between the two groups can hardly be papered over.

这两个团体间的分歧难以掩饰。

This approach not only encourages a greater number of responses, but minimizes the likelihood of stale groupthink.

这种做法不仅鼓励了更多的反应，而且减少跟风的可能性。