共查询到20条相似文献,搜索用时 156 毫秒
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本文采用SIMPLE方法对有流动条件下双组分系统的凝固过程进行数值模拟,求解混合物参数的控制方程,混合物中两相的体积分数和溶质浓度利用平衡相图关系确定,控制方程用有限体积法离散,SIMPLE方法求解,对NH4Cl水溶液的流动凝固过程进行了数据模拟,给出数据求解的结果,分析了对流和输动现象对宏观相界面形态,相变速率和最终宏观的组分分凝现象的影响。 相似文献
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本文用液体-颗粒两相流动的方程来描述心血管系统中的血液流动、对导出的二维两相流动基本方程用SIMPLE及IPSA算法进行了离散求解.算例的结果显示:两相系统的描述方法确实能对红组胞的一些运动特性给出恰当的解释,具有单相流动法不可比拟的优点。 相似文献
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基于Fluent软件的汽车散热器双侧三维数值模拟 总被引:1,自引:0,他引:1
本文在对汽车散热器的物理模型单元进行了合理的简化处理后,利用Fluent软件,采用SIMPLE算法和标准k—e湍流模型,通过求解三维N—S方程和能量方程模拟了空气在散热器空气侧流动,水在散热器的水侧流动的双侧传热过程。计算出散热器的平均换热系数,并通过模拟两种尺寸和五种流速的情况展示出提高散热器的散热效率的几种常规做法。 相似文献
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概述了目前国内外镍基单晶高温合金定向凝固数值模拟的研究进展,定向凝固过程的数值模拟由宏观向微观转变,详细介绍了微观组织数值模拟的几种主要方法:决定论方法、随机论方法和相场方法,评述了这几种方法的特点以及局限性,指出宏观和微观现象的完整耦合可以对镍基单晶高温合金凝固过程做出更加准确的模拟预测。 相似文献
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概述了目前国内外镍基单晶高温合金定向凝固数值模拟的研究进展,定向凝固过程的数值模拟由宏观向微观转变,详细介绍了微观组织数值模拟的几种主要方法:决定论方法、随机论方法和相场方法,评述了这几种方法的特点以及局限性,指出宏观和微观现象的完整耦合可以对镍基单晶高温合金凝固过程做出更加准确的模拟预测。 相似文献
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根据JB/T9066—1999标准,设计并建立了空调机组性能测试室;利用k-ε湍流模型,对空调机组性能测试室内气流组织进行三维空间数值模拟;采用交错网格控制容积法将计算区域进行离散,用SIMPLE算法求解离散控制方程。模拟结果表明,测试室内的温度、速度分布均匀,满足柜式风机盘管机组的测试要求,并与实测数据相吻合。 相似文献
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本文首先在综合横焰玻璃熔窑理论及实践的基础上 ,建立了具有实用意义的燃油浮法玻璃熔窑火焰空间燃烧过程的三维数学模型。它包括气相流动与传热模型和雾化油滴燃烧的轨道模型 ,前者以流体力学理论基础 ,采用 SIMPL E方法求解 ;后者用单元内颗粒源法来处理 ,并对计算结果分别进行图形、图像模拟。通过对日产 4 0 0吨燃油浮法玻璃熔窑火焰空间的温度分布研究表明 ,该三维数学模型比较全面地反映了火焰空间温度分布的规律 ,与窑炉实际工况较吻合 ;而对温度场的图像模拟则使温度场更具直观性。 相似文献
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快速凝固高强高导铜合金的研究现状及展望 总被引:1,自引:0,他引:1
本文综述了快速凝固高强度高导电率铜合金的研究现状 ,并对将来的发展趋势作了展望。指出 ,快速凝固铜合金的凝固过程对合金的最终显微组织结构起重要作用 ,因而 ,对其进行深入细致的研究具有重要意义。 相似文献
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本文通过比较离心SHS技术和重力分离SHS技术的合成工艺 ,从理论上阐述合成SHS陶瓷内衬复合管所涉及的燃烧合成、液相分离和陶瓷凝固三个重要过程 ,并着重探讨了SHS陶瓷内衬复合管技术研究领域中陶瓷致密化问题 ,提出了提高SHS陶瓷内衬复合管质量的有效途径 相似文献
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Deep Samanta Nicholas Zabaras 《International journal for numerical methods in engineering》2005,64(13):1769-1799
Solidification of dendritic alloys is modelled using stabilized finite element techniques to study convection and macrosegregation driven by buoyancy and shrinkage. The adopted governing macroscopic conservation equations of momentum, energy and species transport are derived from their microscopic counterparts using the volume‐averaging method. A single domain model is considered with a fixed numerical grid and without boundary conditions applied explicitly on the freezing front. The mushy zone is modelled here as a porous medium with either an isotropic or an anisotropic permeability. The stabilized finite‐element scheme, previously developed by authors for modelling flows with phase change, is extended here to include effects of shrinkage, density changes and anisotropic permeability during solidification. The fluid flow scheme developed includes streamline‐upwind/Petrov–Galerkin (SUPG), pressure stabilizing/Petrov–Galerkin, Darcy stabilizing/Petrov–Galerkin and other stabilizing terms arising from changes in density in the mushy zone. For the energy and species equations a classical SUPG‐based finite element method is employed with minor modifications. The developed algorithms are first tested for a reference problem involving solidification of lead–tin alloy where the mushy zone is characterized by an isotropic permeability. Convergence studies are performed to validate the simulation results. Solidification of the same alloy in the absence of shrinkage is studied to observe differences in macrosegregation. Vertical solidification of a lead–tin alloy, where the mushy zone is characterized by an anisotropic permeability, is then simulated. The main aim here is to study convection and demonstrate formation of freckles and channels due to macrosegregation. The ability of stabilized finite element methods to model a wide variety of solidification problems with varying underlying phenomena in two and three dimensions is demonstrated through these examples. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
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利用蚀刻硅技术制造的微机械构件 ,由于特殊的制作工艺而需要对其材料的机械性能如杨氏模量等进行测试。这是随微机械技术的产生而提出的一个新课题。文章综述了微机械材料杨氏模量的静态测试法。提出了微机械材料杨氏模量的动态测试法———静电激振法。这种方法具有测试装置简单、测量容易、适应性广等特点 相似文献
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Yih-Jena Jan 《Computational Mechanics》2007,40(2):217-231
The finite volume based numerical approach is used to simulate phase-change processes including natural convection. This approach
is based on a cell-by-cell, thermally driven mushy cell tracking equation, developed in Part I [20], to trace the front at
which phase-change occurs. A mushy cell is a specialized cell where the interface between liquid and solid phases is located.
In this paper, the mushy cell tracking equation and the associated boundary condition around the mushy cells are derived in
a general manner and shown to have the same form as that used in Part I. The SIMPLE algorithm is adopted to solve the flow,
including pressure field, as well, in the liquid phase and a conjugate gradient method is used when solving the system of
discretized equations. To reduce computational time, an acceleration technique, based on a justified quasi-steady state assumption,
is adopted. The proposed numerical method is applied to simulate the solidification and melting of Tin with natural convection.
The numerical predictions are compared well with the available experimental data and previously published numerical results.
Specifically, these comparisons demonstrate that the proposed methodology is capable of predicating the location of moving
fronts and the temperature distributions for phase-change processes with natural convection. 相似文献
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A parallel implementation of a finite volume method for the solution of the Navier-Stokes equations on a distributed computing
environment through Parallel Virtual Machine (PVM) is reported. The numerical method is implicit and is based on the SIMPLE
algorithm in which the system of equations is discretised using a hybrid scheme. An Alternative Direction Implicit (ADI) scheme,
and the Thomas tri-diagonal solver are used to solve the algebraic equations. The parallelization of the program is implemented
by a domain decomposition strategy on MIMD parallel architectures using PVM platform. The program was tested for laminar flow
in a cavity. The parallelisation strategy and performance are discussed. It is concluded that the efficiency is strongly dependent
on the grid size, block numbers and the number of processors. Different strategies to improve the computational efficiency
are proposed. 相似文献
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Nicholas Zabaras Deep Samanta 《International journal for numerical methods in engineering》2004,60(6):1103-1138
A stabilized equal‐order velocity–pressure finite element algorithm is presented for the analysis of flow in porous media and in the solidification of binary alloys. The adopted governing macroscopic conservation equations of momentum, energy and species transport are derived from their microscopic counterparts using the volume‐averaging method. The analysis is performed in a single domain with a fixed numerical grid. The fluid flow scheme developed includes SUPG (streamline‐upwind/Petrov–Galerkin), PSPG (pressure stabilizing/Petrov–Galerkin) and DSPG (Darcy stabilizing/Petrov–Galerkin) stabilization terms in a variable porosity medium. For the energy and species equations a classical SUPG‐based finite element method is employed. The developed algorithms were tested extensively with bilinear elements and were shown to perform stably and with nearly quadratic convergence in high Rayleigh number flows in varying porosity media. Examples are shown in natural and double diffusive convection in porous media and in the directional solidification of a binary‐alloy. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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ABSTRACT The numerical study of the pneumatic transport in a two-phase turbulent horizontal flow at high loading, q> 10, has been developed. The effect of turbulence is considered by a coupled item of interaction force between solid particles and gaseous species. The equations are solved through the modified SIMPLE method. The steady solution has been carried out by using the time-dependent method. As a special example, pneumatic transport of a mixture of a gas and a solid in hollow cylinders of polyethylene in a turbulent horizontal flow is solved. (Diameter of the pipe, D: 55 m Length, L: 36.73 m, d: 3 to 4 mm, P S: 958 kg/m3 ). The results show excellent agreement between the numerical calculation and the experiment. Some problems for pneumatic transport at high solids loading have been discussed. The present method is also applicable to pneumatic conveyance in telescoping pipes. 相似文献