当期目录

2018年 第39卷 第9期    刊出日期：2018-09-01

上一期    下一期

论文

The effect of initial geometric imperfection on the nonlinear resonance of functionally graded carbon nanotube-reinforced composite rectangular plates

R. GHOLAMI, R. ANSARI

2018, 39(9):  1219-1238.  doi:10.1007/s10483-018-2367-9

摘要 ( 570 )   HTML   PDF (412KB) ( 201 )  

参考文献 | 相关文章 | 多维度评价

The purpose of the present study is to examine the impact of initial geometric imperfection on the nonlinear dynamical characteristics of functionally graded carbon nanotube-reinforced composite (FG-CNTRC) rectangular plates under a harmonic excitation transverse load. The considered plate is assumed to be made of matrix and single-walled carbon nanotubes (SWCNTs). The rule of mixture is employed to calculate the effective material properties of the plate. Within the framework of the parabolic shear deformation plate theory with taking the influence of transverse shear deformation and rotary inertia into account, Hamilton's principle is utilized to derive the geometrically nonlinear mathematical formulation including the governing equations and corresponding boundary conditions of initially imperfect FG-CNTRC plates. Afterwards, with the aid of an efficient multistep numerical solution methodology, the frequency-amplitude and forcing-amplitude curves of initially imperfect FG-CNTRC rectangular plates with various edge conditions are provided, demonstrating the influence of initial imperfection, geometrical parameters, and edge conditions. It is displayed that an increase in the initial geometric imperfection intensifies the softening-type behavior of system, while no softening behavior can be found in the frequency-amplitude curve of a perfect plate.



Comparison and analysis of two Coulomb friction models on the dynamic behavior of slider-crank mechanism with a revolute clearance joint

Xudong ZHENG, Runsen ZHANG, Qi WANG

2018, 39(9):  1239-1258.  doi:10.1007/s10483-018-2371-9

摘要 ( 480 )   HTML   PDF (1233KB) ( 155 )  

参考文献 | 相关文章 | 多维度评价

The objective of this study is to investigate the effects of the Coulomb dry friction model versus the modified Coulomb friction model on the dynamic behavior of the slider-crank mechanism with a revolute clearance joint. The normal and tangential forces acting on the contact points between the journal and the bearing are described by using a Hertzian-based contact force model and the Coulomb friction models, respectively. The dynamic equations of the mechanism are derived based on the Lagrange equations of the first kind and the Baumgarte stabilization method. The frictional force is solved via the linear complementarity problem (LCP) algorithm and the trial-and-error algorithm. Finally, three numerical examples are given to show the influence of the two Coulomb friction models on the dynamic behavior of the mechanism. Numerical results show that due to the stick friction, the slider-crank mechanism may exhibit stick-slip motion and can balance at some special positions, while the mechanism with ideal joints cannot.

Study on a straight dislocation in an icosahedral quasicrystal with piezoelectric effects

Lianhe LI, Guanting LIU

2018, 39(9):  1259-1266.  doi:10.1007/s10483-018-2363-9

摘要 ( 478 )   HTML   PDF (242KB) ( 78 )  

参考文献 | 相关文章 | 多维度评价

An electro-elastic analysis is performed on an icosahedral quasicrystal with piezoelectric effects containing a straight dislocation. The closed-form expressions for the elastic and electric fields are obtained using the extended Stroh formalism. The effects of piezoelectric constant on the phonon displacement, phason displacement, and electric potential are discussed in detail.

Direct numerical simulation of turbulent flows through concentric annulus with circumferential oscillation of inner wall

Yichen YAO, Chunxiao XU, Weixi HUANG

2018, 39(9):  1267-1276.  doi:10.1007/s10483-018-2364-7

摘要 ( 426 )   HTML   PDF (1095KB) ( 139 )  

参考文献 | 相关文章 | 多维度评价

Periodic wall oscillations in the spanwise or circumferential direction can greatly reduce the friction drag in turbulent channel and pipe flows. In a concentric annulus, the constant rotation of the inner cylinder can intensify turbulence fluctuations and enhance skin friction due to centrifugal instabilities. In the present study, the effects of the periodic oscillation of the inner wall on turbulent flows through concentric annulus are investigated by the direct numerical simulation (DNS). The radius ratio of the inner to the outer cylinders is 0.1, and the Reynolds number is 2 225 based on the bulk mean velocity U_m and the half annulus gap H. The influence of oscillation period is considered. It is found that for short-period oscillations, the Stokes layer formed by the circumferential wall movement can effectively inhibit the near-wall coherent motions and lead to skin friction reduction, while for long-period oscillations, the centrifugal instability has enough time to develop and generate new vortices, resulting in the enhancement of turbulence intensity and skin friction.

Large eddy simulation of turbulent premixed piloted flame using artificial thickened flame model coupled with tabulated chemistry

Zhou YU, Hongda ZHANG, Taohong YE, Minming ZHU

2018, 39(9):  1277-1294.  doi:10.1007/s10483-018-2370-9

摘要 ( 487 )   HTML   PDF (1344KB) ( 141 )  

参考文献 | 相关文章 | 多维度评价

A sub-grid scale (SGS) combustion model, which combines the artificial thickened flame (ATF) model with the flamelet generated manifold (FGM) tabulation method, is proposed. Based on the analysis of laminar flame structures, two self-contained flame sensors are used to track the diffusion and reaction processes with different spatial scales in the flame front, respectively. The dynamic formulation for the proposed SGS combustion model is also performed. Large eddy simulations (LESs) of Bunsen flame F3 are used to evaluate the different SGS combustion models. The results show that the proposed SGS model has the ability in predicting the distributions of temperature and velocity reasonably, while the predictions for the distributions of some species need further improvement. The snapshots of instantaneous normalized progress variables reveal that the flame is more remarkably and severely wrinkled at the flame tip for flame F3. More satisfactory results obtained by the dynamic model indicate that it can preserve the premixed flame propagation characteristics better.

Chemically reactive and radiative von Kármán swirling flow due to a rotating disk

M. KHAN, J. AHMED, L. AHMAD

2018, 39(9):  1295-1310.  doi:10.1007/s10483-018-2368-9

摘要 ( 718 )   HTML   PDF (425KB) ( 183 )  

参考文献 | 相关文章 | 多维度评价

A new mathematical model is presented to study the heat and mass transfer characteristics of magnetohydrodynamic (MHD) Maxwell fluid flow over a convectively heated stretchable rotating disk. To regulate the fluid temperature at the surface, a simple isothermal model of homogeneous-heterogeneous reactions is employed. The impact of nonlinear thermal radiative heat flux on thermal transport features is studied. The transformed nonlinear system of ordinary differential equations is solved numerically with an efficient method, namely, the Runge-Kutta-Felberg fourth-order and fifth-order (RKF45) integration scheme using the MAPLE software. Achieved results are validated with previous studies in an excellent way. Major outcomes reveal that the magnetic flux reduces the velocity components in the radial, angular, and axial directions, and enhances the fluid temperature. Also, the presence of radiative heat flux is to raise the temperature of fluid. Further, the strength of homogeneous-heterogeneous reactions is useful to diminish the concentration of reaction.

Quadratic convective flow of radiated nano-Jeffrey liquid subject to multiple convective conditions and Cattaneo-Christov double diffusion

P. B. SAMPATH KUMAR, B. MAHANTHESH, B. J. GIREESHA, S. A. SHEHZAD

2018, 39(9):  1311-1326.  doi:10.1007/s10483-018-2362-9

摘要 ( 559 )   HTML   PDF (1414KB) ( 122 )  

参考文献 | 相关文章 | 多维度评价

A nonlinear flow of Jeffrey liquid with Cattaneo-Christov heat flux is investigated in the presence of nanoparticles. The features of thermophoretic and Brownian movement are retained. The effects of nonlinear radiation, magnetohydrodynamic (MHD), and convective conditions are accounted. The conversion of governing equations into ordinary differential equations is prepared via stretching transformations. The consequent equations are solved using the Runge-Kutta-Fehlberg (RKF) method. Impacts of physical constraints on the liquid velocity, the temperature, and the nanoparticle volume fraction are analyzed through graphical illustrations. It is established that the velocity of the liquid and its associated boundary layer width increase with the mixed convection parameter and the Deborah number.

Simultaneous impacts of MHD and variable wall temperature on transient mixed Casson nanofluid flow in the stagnation point of rotating sphere

A. MAHDY

2018, 39(9):  1327-1340.  doi:10.1007/s10483-018-2365-9

摘要 ( 548 )   HTML   PDF (864KB) ( 151 )  

参考文献 | 相关文章 | 多维度评价

A numerical analysis is provided to scrutinize time-dependent magnetohydrodynamics (MHD) free and forced convection of an electrically conducting non-Newtonian Casson nanofluid flow in the forward stagnation point region of an impulsively rotating sphere with variable wall temperature. A single-phase flow of nanofluid model is reflected with a number of experimental formulae for both effective viscosity and thermal conductivity of nanofluid. Exceedingly nonlinear governing partial differential equations (PDEs) subject to their compatible boundary conditions are mutated into a system of nonlinear ordinary differential equations (ODEs). The derived nonlinear system is solved numerically with implementation of an implicit finite difference procedure merging with a technique of quasi-linearization. The controlled parameter impacts are clarified by a parametric study of the entire flow regime. It is depicted that from all the exhibited nanoparticles, Cu possesses the best convection. The surface heat transfer and surface shear stresses in the x-and z-directions are boosted with maximizing the values of nanoparticle solid volume fraction ψ and rotation λ. Besides, as both the surface temperature exponent n and the Casson parameter γ upgrade, an enhancement of the Nusselt number is given.

Investigation of Coulomb force effects on ethylene glycol based nanofluid laminar flow in a porous enclosure

M. SHEIKHOLESLAMI

2018, 39(9):  1341-1352.  doi:10.1007/s10483-018-2366-9

摘要 ( 526 )   HTML   PDF (5114KB) ( 120 )  

参考文献 | 相关文章 | 多维度评价

Forced convection heat transfer of ethylene glycol based nanofluid with Fe₃O₄ inside a porous medium is studied using the electric field. The control volume based finite element method (CVFEM) is selected for numerical simulation. The impact of the radiation parameter (R_d), the supplied voltage (△ψ), the volume fraction of nanofluid (φ), the Darcy number (Da), and the Reynolds number (Re) on nanofluid treatment is demonstrated. Results prove that thermal radiation increases the temperature gradient near the positive electrode. Distortion of isotherms increases with the enhance of the Darcy number and the Coulomb force.

Superconvergence analysis of bi-k-degree rectangular elements for two-dimensional time-dependent Schrödinger equation

Jianyun WANG, Yanping CHEN

2018, 39(9):  1353-1372.  doi:10.1007/s10483-018-2369-9

摘要 ( 538 )   HTML   PDF (737KB) ( 118 )  

参考文献 | 相关文章 | 多维度评价

Superconvergence has been studied for long, and many different numerical methods have been analyzed. This paper is concerned with the problem of superconvergence for a two-dimensional time-dependent linear Schrödinger equation with the finite element method. The error estimate and superconvergence property with order O(h^k+1) in the H¹ norm are given by using the elliptic projection operator in the semi-discrete scheme. The global superconvergence is derived by the interpolation post-processing technique. The superconvergence result with order O(h^k+1 + τ²) in the H¹ norm can be obtained in the Crank-Nicolson fully discrete scheme.