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Moncef Aouadi 《热应力杂志》2013,36(3):270-285
The equations of generalized thermoelastic diffusion, based on the theory of Lord and Shulman with one relaxation time, are given in anisotropic media. A variational principle for the governing equations is obtained. Then we show that the variational principle can be used to obtain a uniqueness theorem under suitable conditions. A reciprocity theorem for these equations is given. The obtained results are valid for some special cases that can be deduced from our generalized model. 相似文献
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In the present work, some essential theorems on the linear coupled theory of micropolar thermoelasticity with two temperatures are established. The uniqueness theorem is proved in two distinct approaches without the positive definiteness assumptions on the thermoelastic modulus. The reciprocity theorem is established by the aid of an integral identity that involves two admissible processes at two different instants. The continuous dependence results on the external data are studied. The variational principle of Gurtin type is established. Finally, we solve the problems of concentrated heat source and body force to study the effect of two-temperature influence on the relevant variables. 相似文献
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Ahmed S. El-Karamany 《热应力杂志》2013,36(9):985-1000
The reciprocal theorem is proved and the convolutional variational principle is established for the two-temperature linear anisotropic and inhomogeneous micropolar thermoviscoelastic solid. A proof, based on variational principle of a uniqueness theorem with no restrictions imposed on the relaxation or thermal conductivity tensors except symmetry conditions, is given. The theorems for classical dynamic coupled micropolar-thermoviscoelasticity theory result as special case when the two temperatures coincides. 相似文献
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Moncef Aouadi 《热应力杂志》2013,36(9):923-942
The general equations of motion and constitutive equations, based on the theory of Lord–Shulman with one relaxation time, are derived for a general homogeneous anisotropic medium with a microstructure, taking into account the effects of heat and diffusion. A variational principle for the governing equations is obtained. Then we show that the variational principle can be used to obtain a uniqueness theorem under suitable conditions. A reciprocity theorem for these equations is given. The obtained results are valid for some special cases which can be deduced from our generalized model. 相似文献
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Moncef Aouadi 《热应力杂志》2013,36(8):706-727
In this paper we derive some qualitative results of the coupled theory of thermoelastic diffusion for anisotropic media. We establish a reciprocity relation, which involves two thermoelastic diffusion processes at different instants. We show that this relation can be used to obtain reciprocity, uniqueness and continuous dependence theorems. The reciprocity theorem avoids both the use of the Laplace transform and the incorporation of initial conditions into the equations of motion. The uniqueness theorem is derived without the positive definiteness assumption on the elastic, conductivity and diffusion tensors. We prove also that the reciprocal relation leads to a continuous dependence theorem studied on external body loads. Finally, we prove the existence of a generalized solution by means of the semigroup of linear operators theory. 相似文献
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In this work, a new theory of thermodiffusion in elastic solids is derived using the methodology of fractional calculus. The theories of coupled thermoelastic diffusion and of generalized thermoelastic diffusion problem with one relaxation time follow as limit cases. A variational theorem is then obtained for the governing equations. Finally, a uniqueness and reciprocity theorems for these equations are derived. 相似文献
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The present paper is concerned with the theory of two temperature thermoelasticity with two phase-lags in which the theory of heat conduction in deformable bodies depends on two distinct temperatures – the conductive temperature and the thermodynamic temperature. A generalized heat conduction law with dual-phase-lag effects was proposed by Tzou (1995) for the purpose of considering the delayed response in times due to the microstructural interactions in the heat transport mechanism. Recently, Quintanilla (2008) has proposed to combine this constitutive equation with a two temperature heat conduction theory and has proved that a dual-phase-lag theory with two temperatures is a well-posed problem. In the present work we consider the basic equations concerning this dual-phase lag theory of two temperature thermoelasticity and make an attempt to establish some important theorems in this context. A uniqueness theorem has been established for a homogeneous and isotropic body. An alternative characterization of mixed boundary initial value problem is formulated and a variational principle as well as reciprocal principle have been established. 相似文献
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Heat and mass transfer with condensation in porous media was numerically studied coupling with distributions of temperature, vapor concentration, pressure and water saturation. The transport processes in porous media displayed two distinct stages, or early and late stages. Different characteristics during these stages were described with the consideration of physical nature. A systematical investigation was conducted to explore the influence of different parameters on the processes, including the temperature, the particle diameter, the porosity, and the thermal conductivity of the particle. A modeling experiment was conducted to partially validate the calculation. 相似文献
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在低温太阳能光热光伏联合应用试验台的基础上,结合GB/T 17049—2005,利用Gambit、Ansys Fluent和Tecplot软件,对全玻璃真空管太阳能热水器进行传热传质和强化传热分析。结果表明:所建立的二维数值计算模型,能准确反映同一条件下,全玻璃真空管太阳能热水器的变化趋势;在数值模拟基础上,确定了单面受热时的最佳安装角度为51°,加装反光板类似双面受热的最佳安装角度为38°;在粗略估算和细化分析的基础上,确定了不同真空管结构的最佳导流板长度及安装位置;通过实验和数值模拟,确定了58mm×1 800mm为优化的全玻璃真空管结构。 相似文献
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Zuu-Chang Hong Chaw-En Zhen Chien-Yuh Yang 《Numerical Heat Transfer, Part A: Applications》2013,63(3):293-314
The subsonic gas flows through straight rectangular cross-sectional microchannel with patterned microstructures was simulated using the direct simulation Monte Carlo (DSMC) method. An implicit treatment for low-speed inflow and outflow boundaries for the DSMC of the flows in microelectromechanical systems (MEMS) is employed. The 3-D microchannel flows are simulated with the cross-section aspect ratio ranging between 1 and 5. The comparison between 3-D cases and 2-D case shows that when the aspect ratio < 3, the two extra side-walls in the 3-D case have significant effects on the heat transfer and flow properties. When the aspect ratio increases, the flow pattern and heat transfer characteristics tend to approach those of 2-D results. The 2-D simplification is found to be reasonable when the cross-section aspect ratio is larger than 5. The microchannel flows with microstructures are also calculated with three different Knudsen numbers regime cases, and each case is calculated with three different microstructure temperatures, 273 K, 323 K, and 373 K. One Knudsen numbers regime ranges between 0.72 and 1.8, another regime ranges between 0.24 and 0.6 and the other regime ranges between 0.08 and 0.2. The computations show that the cooling and heating effects of the microstructure temperature on flow properties are enhanced with decreasing Knudsen number, and the higher microstructure temperature accelerates the velocity of the flow at the locations above the microstructures. 相似文献
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The complex model of heat and mass transfer during adsorption and chemical heat conversion is presented. It includes combined effect of physical and chemical adsorption and accompanying ammonia condensation/evaporation directly inside the sorber taking into account the conjugate heat transfer between the sorbent and the heat-transfer fluid. It was found that the specific cooling power and average cooling temperature are one-valued function of a ratio of the sorber length to the mass flow of heat-transfer fluid. The use of condensation/evaporation in a sorbent can increase the temperature effect more than twice. 相似文献
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This paper concerns with the linear theory of micropolar thermoelasticity for materials with voids. We construct the fundamental solution of the system of differential equations in the case of steady oscillations in terms of elementary functions. Some basic properties of this solution are established. 相似文献
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An analysis was carried out to study the efficiency of a straight rectangular fin with a uniform cross-section area when subjected to simultaneous heat and mass transfer mechanisms. The temperature and humidity ratio differences are the driving forces for the heat and mass transfer, respectively. Numerical solutions are obtained for the temperature distribution over the fin surface when the fin surface is dry, fully wet, and partially wet. The psychrometric correlation of an air-water vapor mixture was used to simulate the relation between the temperature and humidity ratio instead of the linear approximate correlations used in the literature. The effect of atmospheric pressure on the fin efficiency was also studied, in addition to fin optimum thickness for specific operating conditions. The numerical solution was compared with those of previous studies in order to find if the linear model in the published analytical results are near to the real situation. It is found that the linear model for the relation between the humidity ratio and the temperature used by Wu and Bong is a reasonable engineering approximation for small values of the fin parameter and at low relative humidities. 相似文献
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