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2013年 第34卷 第5期    刊出日期：2013-05-03

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Influence of random uncertainties of anisotropic fibrous model parameters on arterial pressure estimation

A. EDDHAHAK-OUNI I. MASSON F. MOHAND-KACI M.ZIDI

2013, 34(5):  529-540.  doi:10.1007/s10483-013-1688-6

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This paper deals with a stochastic approach based on the principle of the maximum entropy to investigate the effect of the parameter random uncertainties on the arterial pressure. Motivated by a hyperelastic, anisotropic, and incompressible constitutive law with fiber families, the uncertain parameters describing the mechanical behavior are considered. Based on the available information, the probability density functions are attributed to every random variable to describe the dispersion of the model parameters. Numerous realizations are carried out, and the corresponding arterial pressure results are compared with the human non-invasive clinical data recorded over a mean cardiac cycle. Furthermore, the Monte Carlo simulations are performed, the convergence of the probabilistic model is proven. The different realizations are useful to define a reliable confidence
region, in which the probability to have a realization is equal to 95%. It is shown through the obtained results that the error in the estimation of the arterial pressure can reach 35% when the estimation of the model parameters is subjected to an uncertainty ratio of 5%. Finally, a sensitivity analysis is performed to identify the constitutive law relevant parameters for better understanding and characterization of the arterial wall mechanical
behaviors.

Forced convection heat transfer due to different inclination angles of splitter behind square cylinder

S. M. SEYYEDI D. D. GANJI M. GORJI H. BARARNIA S. SOLEIMANI

2013, 34(5):  541-558.  doi:10.1007/s10483-013-1689-9

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A numerical investigation is carried out to study the effect of splitter’s inclination angle behind an inclined square cylinder on the forced convection heat transfer in a plan channel using the lattice Boltzmann method (LBM). The simulations are conducted for the pertinent parameters in the following ranges: the Reynolds number Re=50–300, the gap ratio G/d = 2, and the splitter’s inclination angle θ = 0 ^?–90^?. The results show
that with the increase in the angle of the splitter, the drag coefficient initially decreases and then increases. Moreover, the time-averaged Nusselt number at a certain angle increases noticeably.

论文

Finite element solution of heat and mass transfer flow with Hall current, heat source, and viscous dissipation

S. SIVAIAH;R. SRINIVASA-RAJU

2013, 34(5):  559-570.  doi:10.1007/s10483-013-1690-8

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The aim of the paper is to investigate the effect of heat and mass transfer on the unsteady magnetohydrodynamic free convective flow with Hall current, heat source, and viscous dissipation. The problem is governed by the system of coupled non-linear partial differential equations whose exact solution is difficult to obtain. Therefore, the problem is solved by using the Galerkin finite element method. The effects of the various
parameters like Hall current, Eckert number, heat source parameter, Prandtl number, and Schmidt number on the velocity components, the temperature, and the concentration are also examined through graphs.

Mesoscopic numerical computation model of air-diffusion electrode of metal/air batteries

刘晓毅 徐献芝

2013, 34(5):  571-576.  doi:10.1007/s10483-013-1691-9

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This work creates a droplet battery model based on the electrolyte performance in the porous electrode, studies the current density on the mesoscopic scale, and explains how the mesoscopic structure of the porous electrode influences the current density on the air-diffusion electrode. Near the three-phase line, there is a strong band containing nearly 80% current. For porous electrodes, the total current is proportional to
the length of the strong band. Thus, it can be inferred that on the macroscopic scale, the longer the total length of the strong band on unit area is, the larger the current density is.

Validation of 1D model for methane/air/Pt combustion in stagnation flow

刘明侯 邢丹 陆雨洲 朱会元

2013, 34(5):  577-588.  doi:10.1007/s10483-013-1692-7

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A 2D model is built on the package of FLUENT to study the effects of radial aspect ratio (R/W), length-to-width ratio (L/W), strain rate (SR), and buoyancy (Ri=Gr/Re²) on the validation of the simplified 1D model. In the present 2D model, the methane/air homogeneous reaction mechanism of Peters and the methane/air/platinum heterogeneous reaction mechanism of Deutschmann are applied. By comparison between the 1D and 2D numerical results, it is found that the validation of 1D model is highly related with the catalytic stagnation reactor configuration. For length-to-width ratio L/W = 1 configuration, 1D laminar model is applicable when the radial aspect ratio R/W > 0.4. For R/W = 0.6, the reactor exhibited 1D characteristics when L/W < 1. Compared with the temperature and species profiles, the velocity distribution along the axis is more sensitive to the change of radial aspect ratio and length-to-width ratio. With increasing of the strain rate, the flame front goes closer to the catalytic wall surface and
the difference between the 1D and 2D results decreases. For a valid 1D simulation, it is recommended that the strain rate should be greater than 20 s⁻¹. The effects of natural convection can be neglected when Ri< 5.

Spiral piezoelectric transducer in torsional motion as low-frequency power harvester

王海仁 胡洪平 杨嘉实 胡元太

2013, 34(5):  589-596.  doi:10.1007/s10483-013-1693-x

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A structure consisting of a spiral piezoelectric transducer and a concentrated mass is proposed as a low-frequency piezoelectric power harvester. A theoretical model is developed for the system from the theory of piezoelectricity. An analysis is performed to demonstrate the low-frequency nature of the system. Other basic characteristics of the power harvester including the output power, voltage, and efficiency are also calculated and examined.

Two-dimensional analyses of delamination buckling of symmetrically cross-ply rectangular laminates

薛江红 罗庆姿 韩峰 刘人怀

2013, 34(5):  597-612.  doi:10.1007/s10483-013-1694-7

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The conventional approach to analysis the buckling of rectangular laminates containing an embedded delamination subjected to the in-plane loading is to simplify the laminate as a beam-plate from which the predicted buckling load decreases as the length of the laminate increases. Two-dimensional analyses are employed in this paper by extending the one-dimensional model to take into consideration of the influence of the
delamination width on the buckling performance of the laminates. The laminate is simply supported containing a through width delamination. A new parameter β defined as the ratio of delamination length to delamination width is introduced with an emphasis on the influence of the delamination size. It is found that (i) when the ratio β is greater than one snap-through buckling prevails, the buckling load is determined by the delamination size
and depth only; (ii) as the ratio β continues to increase, the buckling load will approach to a constant value. Solutions are verified with the well established results and are found in good agreement with the latter.

Moment Lyapunov exponent for three-dimensional system under real noise excitation

李胜宏 刘先斌

2013, 34(5):  613-626.  doi:10.1007/s10483-013-1695-8

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The pth moment Lyapunov exponent of a two-codimension bifurcation system excited parametrically by a real noise is investigated. By a linear stochastic transformation, the differential operator of the system is obtained. In order to evaluate the asymptotic expansion of the moment Lyapunov exponent, via a perturbation method, a ralevant eigenvalue problem is obtained. The eigenvalue problem is then solved by a Fourier cosine series expansion, and an infinite matrix is thus obtained, whose leading eigenvalue is the second-order of the asymptotic expansion of the moment Lyapunov exponent. Finally, the convergence of procedure is numerically illustrated, and the effects of the system and the noise parameters on the moment Lyapunov exponent are discussed.

Bifurcation and chaos of airfoil with multiple strong nonlinearities

蔡铭 刘卫飞 刘济科

2013, 34(5):  627-636.  doi:10.1007/s10483-013-1696-x

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The bifurcation and chaos phenomena of two-dimensional airfoils with multiple strong nonlinearities are investigated. First, the strongly nonlinear square and cubic plunging and pitching stiffness terms are considered in the airfoil motion equations, and the fourth-order Runge-Kutta simulation method is used to obtain the numerical solutions to the equations. Then, a post-processing program is developed to calculate the physical
parameters such as the amplitude and the frequency based on the discrete numerical solutions. With these parameters, the transition of the airfoil motion from balance, period, and period-doubling bifurcations to chaos is emphatically analyzed. Finally, the critical points of the period-doubling bifurcations and chaos are predicted using the Feigenbaum constant and the first two bifurcation critical values. It is shown that the numerical simulation method with post-processing and the prediction procedure are capable of simulating and predicting the bifurcation and chaos of airfoils with multiple strong nonlinearities.

Optimal convergence rates for three-dimensional turbulent flow equations

边东芬 郭柏灵

2013, 34(5):  637-656.  doi:10.1007/s10483-013-1697-6

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In this paper, the convergence rates of solutions to the three-dimensional turbulent flow equations are considered. By combining the L^p-L^q estimate for the linearized equations and an elaborate energy method, the convergence rates are obtained in various norms for the solution to the equilibrium state in the whole space when the initial perturbation of the equilibrium state is small in the H³-framework. More precisely, the optimal convergence rates of the solutions and their first-order derivatives in the L²-norm are obtained when the L^p-norm of the perturbation is bounded for some p ∈ [1, 6/5 ).