高温作用下混凝土热-水-力耦合损伤分析模型

以混合物理论为基础建立了高温作用下混凝土的热-水-力耦合损伤分析模型．将混凝土视为由固体骨架、液态水、水蒸气、干燥气体和溶解气体共5种组分构成的混合物,模型的宏观平衡方程包括各组分的质量守恒方程、整体的能量守恒方程及动量守恒方程,模型所需的状态方程及本构关系全部给出,最后给出基于4个主要参数（固体骨架位移、气压力、毛细压力和温度）的控制方程．模型考虑了混凝土在高温作用下,水分的蒸发与冷凝、胶结材料的水化及脱水、溶解气的溶解与挥发等相变过程;从材料变形破坏过程中能量耗散特征入手,基于Lemaitre应变等价性假说和能量守恒原理得到力学损伤演化方程,并考虑了高温引起的热损伤对材料力学性能及力学损伤演化规律的影响,建立了热-力耦合损伤本构模型．     

喷涂于运动边界上液体薄膜射流的流变效应

采用非Newton流体的二阶流体模型分析了相对高温的液体熔体薄膜由模口喷出并涂于运动的固体膜上. 讨论了由自由面上温度梯度驱动的非Newton液体薄膜的热毛细流动, 考虑热毛细流动的流变效应. 分析是基于润滑理论近似和摄动理论近似. 得到了液体高度方程和非Newton液体薄膜的热流体力学过程描述, 具体求解了弱流变流体效应的情况.     

交通流流体力学模型与非线性波

介绍了交通流问题中的流体力学描述方法,分析了交通流在受压力和自驱动力等因素作用下所产生的非线性波动现象．这些描述包括LWR运动学模型,考虑动力学效应的高阶模型,考虑超车效应的多车种LWR(Lighthill-Whitham-Richards)模型,以及考虑流通量间断的模型方程．此外,还介绍了LWR网络推广模型在交叉口的Riemann问题求解;提出了描述二维行人流问题的Navier-Stokes-Eikon方程模型并描述了确定行人流运动期盼方向的基本思想．     

解非定常不可压Navier-Stokes方程的压力修正投影法的并行算法研究

1．CNMTZ格式和压力Poisson、方程的快速解法为后面讨论的方便，本节中我们简要介绍一下［1，2］提出的求解上述方程的CNMTZ算法以及相应的压力Poisson方程的快速算法．考虑原始变量非定常不可压N—S方程（INSE）和满足方程（2的初始条件W（；队0），W在边界＊0上给定并满足这里，V＝（。，V厂是速度场，p是压力．方程（1）（2）进行空间离散后可以写成以下形式：其中力（W，t）包括动量方程中的对流项、扩散项和非齐次项的空间差分近似及相应的边界条件，G和D分别为梯度和散度算子的离散形式．它的CNMT格式的PC投影法如下：其…     

含水合物油包水管道输送体系压力波速研究

考虑水合物的相变、油相的压缩性、频率、虚拟质量力及体系的温度和压力的影响,建立了含水合物油包水体系的压力波速方程.研究结果表明,输送过程中水合物对体系的压力波速影响很大,在水合物分解区域,气体的出现使体系的压缩性大幅增加,压力波速急速降低;反之,在水合物生成区域,体系的压缩性减小,压力波速增大.随油水比、管径、温度的减小,压力波速均呈现减小的趋势;随压力、油相密度增加,压力波速呈现增大趋势;压力及温度通过影响水合物的分解速度,对体系压力波速产生影响.     

变质量可控力学系统的相对论性变分原理与运动方程*

本文同时考虑经典变质量和相对论变质量情况,建立了基本形式、Lagrange形式,Nielsen形式和APPell形式的变质量可控力学系统的相对论性D'Alembert原理,得到了变质量非完整可控力学系统在准坐标下和广义坐标下的相对论性方程、Nielsen方程和APPell方程,并讨论了完整系统、常质量系统的相对论性可控力学系统的运动方程。     

二维Navier-Stokes方程同位有限体积法的稳定性改进

1 引言 考虑不可压缩粘性流体的二维Navier-Stokes方程,它由速度压力公式和连续性方程的耦合组成.     

通过有漏孔管道时的层流解析解

研究了通过有漏孔管道时的层流,并解析地求解了动量方程和能量守恒方程．由Hagen-Poiseuille的速度分布,同时定义轴向和径向速度分量的未知函数,得到了压力和质量输运方程,并根据不同的参数,画出其分布图．结果表明,管道中的轴向速度、径向速度、质量输运参数和压力,随着流体沿管道的流动而减小．     

Hertz接触问题的精确的积分方程

本文给出Hertz接触问题的精确积分方程,也就是将压力作用下接触面中各点的水平位移也考虑在内而得到的积分方程.     

渗流过程的混合物理论

本文把渗流过程考虑为混合物的非平衡输运过程,用现代连续统物理混合物理论的基本观点和方法研究流体在多孔介质中的运动。文中考虑了物质不可混溶和组分间质量交换的影响,提出毛管压力方程和有效应力关系作为封闭关系,系统地阐述了多相渗流、双重介质渗流、非Darcy流动等基本的渗流问题,得到了与经典渗流理论一致的结果,给出了考虑诸热力学耦合因素和非线性因素时渗透定律的一般形式。     

Optimization of technology parameters for the plane-strain component in the process of gas quenching

The paper introduces an optimization method for the technology parameters of the plane-strain component in the process of gas quenching. Distortion, residual stress, average surface hardness and standard deviation of surface hardness are regarded as the optimization objectives. A new heat transfer coefficient model is presented, five distinct heat transfer coefficients are used at various regions of the model. The five heat transfer coefficients are regarded as the design variables, and four regressive equations are established by using response surface method. The four equations, respectively represent the relations between the four optimization objectives and the design variables. A multi-objectives optimization model is established, and the multi-objectives optimization model is optimized by the non-linear method. The optimized technology parameters are used to simulate the gas quenching process by FEM software. The quenching results after optimization are compared with those before optimization. The comparison shows that the quenching quality after optimization is better than that before optimization. After optimization, the four optimization objectives are all improved.     

Heat and mass transfer in annular liquid jets: I. Formulation

Heat and mass transfer phenomena in annular liquid jets are analyzed at high Reynolds numbers by means of a model derived from the governing equations that takes into account the effects of surface tension and boundary conditions at the gas–liquid interfaces and the large differences between the thermal and mass diffusivities, densities, dynamic viscosities, and thermal conductivities between gases and liquids. The model clearly illustrates the stiffness in both space and time associated with the concentration, linear momentum and energy boundary layers, and the initial cooling of the gases enclosed by the jet when, starting from a steady state where gases are injected into the volume enclosed by the jet at a rate equal to the heat and mass absorption rates by the liquid, gas injection is stopped. It is shown that, owing to the non-linear integrodifferential coupling between the fluid dynamics and heat and mass transfer processes, the pressure of the gases enclosed by the jet may vary in either a monotonic or an oscillatory manner depending on the large number of non-dimensional parameters that govern the heat and mass transfer phenomena. For the underpressurized jets considered here, it is shown that thermal equilibrium is achieved at a much faster rate than that associated with mass transfer, double diffusive phenomena in the liquid may occur, and the mass and volume of the gases enclosed by the jet may increase or decrease as functions of time until a steady equilibrium condition is reached.     

The heat and moisture transfer balance theory of garment simulation

To establish the human body model to analyze the heat and moisture transfer on body surface, a new explicit definition of rational L-recursion surface is given and the L-recursion surfaces, in Grassmann spaces, are constructed by using blossom method of the homogeneous normal pyramid form. Based on our human body model, the balance theory of garment simulation, the heat and moisture transfer balance equations, called ICAD-balance equations are obtained. The balance theory of garment simulation integrally studies the complex system of human body-fabric-environment. At the same time, the method of obtaining the heat and moisture transfer balance equations is also based on the mass conservation law, the energy conservation law and the Fish law of capillarity. A finite volume method is employed to solve the ICAD-balance equations.     

The heat and moisture transfer balance theory of garment simulation

To establish the human body model to analyze the heat and moisture transfer on body surface, a new explicit definition of rational L-recursion surface is given and the L-recursion surfaces, in Grassmann spaces, are constructed by using blossom method of the homogeneous normal pyramid form. Based on our human body model, the balance theory of garment simulation, the heat and moisture transfer balance equations, called ICAD-balance equations are obtained. The balance theory of garment simulation integrally studies the complex system of human body–fabric–environment. At the same time, the method of obtaining the heat and moisture transfer balance equations is also based on the mass conservation law, the energy conservation law and the Fish law of capillarity. A finite volume method is employed to solve the ICAD-balance equations.     

Heat and mass transfer in annular liquid jets: II. g-jitter

The effects of g-jitter on heat and mass transfer in underpressurized, annular liquid jets are analyzed numerically as a function of the amplitude and frequency of the gravitational modulation by means of a mapping technique that transforms the time-dependent geometry of these jets into a unit square and a conservative finite difference method. It is shown that the pressure coefficient, gas concentration at the jet's inner interface, heat fluxes at the jet's inner and outer interfaces and interfacial temperature are periodic functions of time whose amplitudes increase as the amplitude of the g-jitter is increased, but decrease as the jitter frequency is increased. The pressure coefficient is almost in phase with the heat flux at the jet's outer interface, and out of phase with the mass transfer rate at the jet's inner interface. It is also shown that the temperature field adapts itself rapidly to the imposed gravity modulation, and thermal equilibrium is reached quickly. However, mass transfer phenomena are very slow and require a very long time to become periodic.     

Mathematical simulation of transfer processes in an elliptical channel in a free molecular regime

In the framework of a free molecular regime, we consider the problem of heat and mass transfer in a long channel of constant elliptical cross-section. The diffuse reflection model is used as the boundary condition. The distributions over the channel cross-section are obtained for the mass velocity of a gas and the heat flux vector. Some analytical method is proposed for finding the heat and mass fluxes through the channel cross-section.     

Nonlinear evolution equations for describing waves in bubbly liquids with viscosity and heat transfer consideration

Nonlinear evolution equations of the fourth order and its partial cases are derived for describing nonlinear pressure waves in a mixture liquid and gas bubbles. Influence of viscosity and heat transfer is taken into account. Exact solutions of nonlinear evolution equation of the fourth order are found by means of the simplest equation method. Properties of nonlinear waves in a liquid with gas bubbles are discussed.     

Lattice-Boltzmann Models for heat transfer

A multispeed heat transfer lattice Boltzmann model is presented. The model possesses the perfect gas state equation with arbitrary special heat ratio. The macroscopic conservation equations are derived by the Chapman-Enskog method. The one dimensional simulation for the sinusoidal energy distributions are compared with the theoretical results, showing good agreement. The theoretical conductivity in the energy equation is in accordance with the simulations.     

Numerical study of a mathematical model of a catalytic fuel processor with cocurrent oxidation and conversion flows

The results are presented of the numerical study of a mathematical model in the form of a nonlinear boundary value problem describing the stationary regimes in a catalytic fuel processor. We study a two-dimensional model for the endoblock, with the longitudinal heat and mass transfer by the gas and the transversal heat conductivity along the catalyst in the two-temperature approximation. For the exochannel, a model is considered with the longitudinal heat and mass transfer by the gas flow and the longitudinal heat transfer along the catalytic wall. These two blocks are related to each other through the equality of the temperature and heat flux on the boundary. The results obtained are in good agreement with experimental data.