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2011年 第32卷 第6期    刊出日期：2011-06-01

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论文

Effects of thermal radiation on MHD viscous fluid flow and heat transfer over nonlinear shrinking porous sheet

G. C. SHIT R. HALDAR

2011, 32(6):  677-688.  doi:10.1007/s10483-011-1448-6

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This paper investigates the effects of thermal radiation on the magnetohydrodynamic (MHD) flow and heat transfer over a nonlinear shrinking porous sheet. The surface velocity of the shrinking sheet and the transverse magnetic field are assumed to vary as a power function of the distance from the origin. The temperature dependent viscosity and the thermal conductivity are also assumed to vary as an inverse function and a linear function of the temperature, respectively. A generalized similarity transformation is used to reduce the governing partial differential equations to their nonlinear coupled ordinary differential equations, and is solved numerically by using a finite difference scheme. The numerical results concern with the velocity and temperature profiles as well as the local skin-friction coefficient and the rate of the heat transfer at the porous sheet for different values of several physical parameters of interest.

Articles

Peristaltic flow of Walter’s B fluid in endoscope

S. NADEEM N.S.AKBAR T. HAYAT A. A. HENDI

2011, 32(6):  689-700.  doi:10.1007/s10483-011-1449-7

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The peristaltic flow of a Walter’s B fluid in an endoscope is studied. The problem is modeled in a cylindrical coordinate system. The main theme of the present analysis is to study the endoscopic effects on the peristaltic flow of theWalter’s B fluid. To the best of the authors’ knowledge, no investigation has been made so far in the literatures to study the Walter’s B fluid in an endoscope. Analytical solutions are obtained using the regular perturbation method by taking δ as a perturbation parameter. The approximate analytical solutions for the pressure rise and friction forces are evaluated using numerical integration. The effects of emerging parameters of the Walter’s B fluid are presented graphically.

论文

Wave transmission through laminated composite double-walled cylindrical shell lined with porous materials

K. DANESHJOU H. RAMEZANI R. TALEBITOOTI

2011, 32(6):  701-718.  doi:10.1007/s10483-011-1450-9

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A study on free harmonic wave propagation in a double-walled cylindrical shell, whose walls sandwich a layer of porous materials, is presented within the framework of the classic theory for laminated composite shells. One of the most effective components of the wave propagation through the porous core is estimated with the aid of a flat panel with the same geometrical properties. By considering the effective wave component, the porous layer is modeled as a fluid with equivalent properties. Thus, the model is simplified as a double-walled cylindrical shell trapping the fluid media. Finally, the transmission loss (TL) of the structure is estimated in a broadband frequency, and then the results are compared.

Articles

Analysis of nonlinear stability and post-buckling for Euler-type beam-column structure

朱媛媛 胡育佳 程昌钧

2011, 32(6):  719-728.  doi:10.1007/s10483-011-1451-x

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Based on the assumption of finite deformation, the Hamilton variational principle is extended to a nonlinear elastic Euler-type beam-column structure located on a nonlinear elastic foundation. The corresponding three-dimensional (3D) mathematical model for analyzing the nonlinear mechanical behaviors of structures is established, in which the effects of the rotation inertia and the nonlinearity of material and geometry are considered. As an application, the nonlinear stability and the post-buckling for a linear elastic beam with the equal cross-section located on an elastic foundation are analyzed. One end of the beam is fully fixed, and the other end is partially fixed and subjected to an axial force. A new numerical technique is proposed to calculate the trivial solution, bifurcation points, and bifurcation solutions by the shooting method and the Newton-Raphson iterative method. The first and second bifurcation points and the corresponding bifurcation solutions are calculated successfully. The effects of the foundation resistances and the inertia moments on the bifurcation points are considered.

论文

Particle image velocimetry (PIV) measurements of tip vortex wake structure of wind turbine

肖金平 武杰 陈立 史喆羽

2011, 32(6):  729-738.  doi:10.1007/s10483-011-1452-x

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Large-view flow field measurements using the particle image velocimetry (PIV) technique with high resolution CCD cameras on a rotating 1/8 scale blade model of the NREL UAE phase VI wind turbine are conducted in the engineering-oriented Φ3.2m wind tunnel. The motivation is to establish the database of the initiation and development of the tip vortex to study the flow structure and mechanism of the wind turbine. The results show that the tip vortex first moves inward for a very short period and then moves outward with the wake expansion, while its vorticity decreases with time after being trailed from the trailing edge of the blade tip, and then increases continuously with the rapid rolling-up to form a strong tip vortex. The measurements also indicate that the downstream movement of the tip vortex is nearly linear in the very near wake under the test condition.

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王珑 王同光 罗源

2011, 32(6):  739-748.  doi:10.1007/s10483-011-1453-x

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The non-dominated sorting genetic algorithm (NSGA) is improved with the controlled elitism and dynamic crowding distance. A novel multi-objective optimization algorithm is obtained for wind turbine blades. As an example, a 5 MWwind turbine blade design is presented by taking the maximum power coefficient and the minimum blade mass as the optimization objectives. The optimal results show that this algorithm has good performance in handling the multi-objective optimization of wind turbines, and it gives a Pareto-optimal solution set rather than the optimum solutions to the conventional multiobjective optimization problems. The wind turbine blade optimization method presented in this paper provides a new and general algorithm for the multi-objective optimization of wind turbines.

Articles

Active control scheme for improving mass resolution of film bulk acoustic resonators

贺学锋 刘兴 印显方 温志渝 陈可万

2011, 32(6):  749-756.  doi:10.1007/s10483-011-1454-9

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High mass resolution of sensors based on film bulk acoustic resonators (FBARs) is required for the detection of small molecules with the low concentration. An active control scheme is presented to improve the mass resolution of the FBAR sensors by adding a feedback voltage onto the driving voltage between two electrodes of the FBAR sensors. The feedback voltage is obtained by giving a constant gain and a constant phase shift to the current on the electrodes of the FBAR sensors. The acoustic energy produced by the feedback voltage partly compensates the acoustic energy loss due to the material damping and the acoustic scattering, and thus improves the quality factor and the mass resolution of the FBAR sensors. An explicit expression relating to the impedance and the frequency for an FBAR sensor with the active control is derived based on the continuum theory by neglecting the influence of the electrodes. Numerical simulations show that the impedance of the FBAR sensor strongly depends on the gain and the phase shift of the feedback voltage, and the mass resolution of the FBAR sensor can greatly be improved when the appropriate gain and the phase shift of the feedback voltage are used. The active control scheme also provides an effective solution to improve the resolution of the quartz crystal microbalance (QCM).

Analysis on high-temperature oxidation and growth stress of iron-based alloy using phase field method

杨帆 刘彬 方岱宁

2011, 32(6):  757-764.  doi:10.1007/s10483-011-1455-8

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High-temperature oxidation is an important property to evaluate thermal protection materials. However, since oxidation is a complex process involving microstructure evolution, its quantitative analysis has always been a challenge. In this work, a phase field method (PFM) based on the thermodynamics theory is developed to simulate the oxidation behavior and oxidation induced growth stress. It involves microstructure evolution and solves the problem of quantitatively computational analysis for the oxidation behavior and growth stress. Employing this method, the diffusion process, oxidation performance, and stress evolution are predicted for Fe-Cr-Al-Y alloys. The numerical results agree well with the experimental data. The linear relationship between the maximum growth stress and the environment oxygen concentration is found. PFM provides a powerful tool to investigate high-temperature oxidation in complex environments.

Experimental and numerical investigation on sound generation from airfoil-flow interaction

江旻 李晓东 周家检

2011, 32(6):  765-776.  doi:10.1007/s10483-011-1456-7

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Aerodynamic noise due to interaction between incoming turbulence and rotating blades is an important component in the wind turbine noise. The rod-airfoil configuration is used to investigate the interactive phenomenon experimentally and numerically. Distribution of unsteady pressure on the airfoil surface is measured for different rod positions and airfoil attack angles. Two National Advisory Committee for Aeronatics (NACA) airfoils, NACA0012 and NACA0018, and two wind turbine airfoils, S809 and S825 are investigated. In addition, for low angles of attack, the flow field around the airfoil’s leading edge is investigated with the particle image velocimetry (PIV). The experimental results indicate that unsteady pressure disturbances on the airfoil surface are related to the rod vortex shedding. Meanwhile, the interaction flow field of the rod and NACA0012 airfoil is simulated with the unsteady Reynolds averaged Navier-Stokes method (URANS), and the obtained pressure spectra are compared with the experimental results.

Stability and dispersion analysis of reproducing kernel collocation method for transient dynamics

罗汉中 刘学文 黄醒春

2011, 32(6):  777-788.  doi:10.1007/s10483-011-1457-6

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A reproducing kernel collocation method based on strong formulation is introduced for transient dynamics. To study the stability property of this method, an algorithm based on the von Neumann hypothesis is proposed to predict the critical time step. A numerical test is conducted to validate the algorithm. The numerical critical time step and the predicted critical time step are in good agreement. The results are compared with those obtained based on the radial basis collocation method, and they are in good agreement. Several important conclusions for choosing a proper support size of the reproducing kernel shape function are given to improve the stability condition.

Essential consistency of pressure Poisson equation method and projection method on staggered grids

王艺

2011, 32(6):  789-794.  doi:10.1007/s10483-011-1458-6

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A new pressure Poisson equation method with viscous terms is established on staggered grids. The derivations show that the newly established pressure equation has the identical equation form in the projection method. The results show that the two methods have the same velocity and pressure values except slight differences in the CPU time.

Stokes flow before plane boundary with mixed stick-slip boundary conditions

N. AKHTAR G. A. H. CHOWDHURY S.K.SEN

2011, 32(6):  795-804.  doi:10.1007/s10483-011-1459-8

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A general theorem for the Stokes flow over a plane boundary with mixed tick-slip boundary conditions is established. This is done by using a representation for the velocity and pressure fields in the three-dimensional Stokes flow in terms of a biharmonic function and a harmonic function. The earlier theorem for the Stokes flow due to fundamental singularities before a no-slip plane boundary is shown to be a special case of the present theorem. Furthermore, in terms of the Stokes stream function, a corollary of the theorem is also derived, providing a solution to the problem of the axisymmetric Stokes flow along a rigid plane with stick-slip boundary conditions. The formulae for the drag and torque exerted by the fluid on the boundary are established. An illustrative example is given.

Almost sure T-stability and convergence for random iterative algorithms

张石生 王雄瑞 刘敏 朱浸华

2011, 32(6):  805-810.  doi:10.1007/s10483-011-1460-6

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The purpose of this paper is to study the almost sure T-stability and convergence of Ishikawa-type and Mann-type random iterative algorithms for some kind of φ-weakly contractive type random operators in a separable Banach space. Under suitable conditions, the Bochner integrability of random fixed points for this kind of random operators and the almost sure T-stability and convergence for these two kinds of random iterative algorithms are proved.