Table of Content

01 August 2017, Volume 38 Issue 8

Previous Issue    Next Issue

Articles

Fracture analysis of magnetoelectroelastic bimaterials with imperfect interfaces by symplectic expansion

Xinsheng XU, Zhenzhen TONG, Dalun RONG, Xianhe CHENG, Chenghui XU, Zhenhuan ZHOU

2017, 38(8):  1043-1058.  doi:10.1007/s10483-017-2222-9

Abstract ( 768 )   HTML   PDF (447KB) ( 257 )  

References | Related Articles | Metrics

A Hamiltonian-based analytical method is used to study the mode III interface cracks in magnetoelectroelastic bimaterials with an imperfect interface. By introducing an unknown vector, the governing equations are reformulated in sets of first-order ordinary differential equations. Using separation of variables, eigensolutions in the symplectic space are obtained. An exact solution of the unknown vector is obtained and expressed in terms of symplectic eigensolutions. Singularities of mechanical, electric, and magnetic fields are evaluated with the generalized intensity factors. Comparisons are made to verify accuracy and stability of the proposed method. Numerical examples including mixed boundary conditions are given.

Thermal buckling analysis of functionally graded cylindrical shells

Zeqing WAN, Shirong LI

2017, 38(8):  1059-1070.  doi:10.1007/s10483-017-2225-7

Abstract ( 505 )   HTML   PDF (315KB) ( 248 )  

References | Related Articles | Metrics

Thermal buckling behavior of cylindrical shell made of functionally graded material (FGM) is studied. The material constituents are composed of ceramic and metal. The material properties across the shell thickness are assumed to be graded according to a simple power law distribution in terms of the volume fraction rule of mixtures. Based on the Donnell shell theory, a system of dimensionless partial differential equations of buckling in terms of displacement components is derived. The method of separation of variables is used to transform the governing equations to ordinary differential equations (ODEs). A shooting method is used to search for the numerical solutions of the differential equations under two types of boundary conditions. Effects of the power law index, the dimensionless geometrical parameters, and the temperature ratio on the critical buckling temperature are discussed in detail.

Duality in interaction potentials for curved surface bodies and inside particles

Dan WANG, Yajun YIN, Jiye WU, Zheng ZHONG

2017, 38(8):  1071-1090.  doi:10.1007/s10483-017-2223-9

Abstract ( 576 )   HTML   PDF (840KB) ( 152 )  

References | Related Articles | Metrics

Based on the viewpoint of duality, this paper studies the interaction between a curved surface body and an inside particle. By convex/concave bodies with geometric duality, interaction potentials of particles located outside and inside the curved surface bodies are shown to have duality. With duality, the curvature-based potential between a curved surface body and an inside particle is derived. Furthermore, the normal and tangential driving forces exerted on the particle are studied and expressed as a function of curvatures and curvature gradients. Numerical experiments are designed to test accuracy of the curvature-based potential.

Fractional-order generalized thermoelastic diffusion theory

Chunbao XIONG, Yanbo NIU

2017, 38(8):  1091-1108.  doi:10.1007/s10483-017-2230-9

Abstract ( 456 )   HTML   PDF (365KB) ( 200 )  

References | Related Articles | Metrics

The present work aims to establish a fractional-order generalized themoelastic diffusion theory for anisotropic and linearly thermoelastic diffusive media. To numerically handle the multi-physics problems expressed by a sequence of incomplete differential equations, particularly by a fractional equation, a generalized variational principle is obtained for the unified theory using a semi-inverse method. In numerical implementation, the dynamic response of a semi-infinite medium with one end subjected to a thermal shock and a chemical potential shock is investigated using the Laplace transform. Numerical results, i.e., non-dimensional temperature, chemical potential, and displacement, are presented graphically. The influence of the fractional order parameter on them is evaluated and discussed.

Selective enhancement of oblique waves caused by finite amplitude second mode in supersonic boundary layer

Cunbo ZHANG, Jisheng LUO

2017, 38(8):  1109-1126.  doi:10.1007/s10483-017-2227-9

Abstract ( 471 )   HTML   PDF (7318KB) ( 104 )  

References | Related Articles | Metrics

Nonlinear interactions of the two-dimensional (2D) second mode with oblique modes are studied numerically in a Mach 6.0 flat-plate boundary layer, focusing on its selective enhancement effect on amplification of different oblique waves. Evolution of oblique modes with various frequencies and spanwise wavenumbers in the presence of 2D second mode is simulated successively, using a modified parabolized stability equation (PSE) method, which is able to simulate interaction of two modes with different frequencies efficiently. Numerical results show that oblique modes in a broad band of frequencies and spanwise wavenumbers can be enhanced by the finite amplitude 2D second mode instability wave. The enhancement effect is accomplished by interaction of the 2D second mode, the oblique mode, and a forced mode with difference frequency. Two types of oblique modes are found to be more amplified, i.e., oblique modes with frequency close to that of the 2D second mode and low-frequency first mode oblique waves. Each of them may correspond to one type of transition routes found in transition experiments. The spanwise wavenumber of the oblique wave preferred by the nonlinear interaction is also determined by numerical simulations.

Triad resonant wave interactions in electrically charged jets

S. ORIZAGA, D. N. RIAHI

2017, 38(8):  1127-1148.  doi:10.1007/s10483-017-2229-9

Abstract ( 352 )   HTML   PDF (4502KB) ( 80 )  

References | Related Articles | Metrics

Nonlinear instability in electrically charged jets is studied using the governing electro-hydrodynamic equations describing stretching and thinning of a liquid jet. A jet flow system subject to both space and time evolving disturbances is considered. At the linear stage, the Rayleigh and conducting jet flow instability modes are uncovered. Nonlinear instability in the flow is explored via triad resonant waves which uncover favorable operating modes not previously detected in the linear study of the problem. In particular, the jet radius is significantly reduced, and the electric field of the jet is properly oriented under the nonlinear study. It is found that taking into account the resonance triad modes provides a better mathematical description of a jet that stretches and thins due to tangential electric field effects. Both linear and nonlinear instability results in the jet flow system are presented and discussed.

Effect of inertial particles with different specific heat capacities on heat transfer in particle-laden turbulent flow

Caixi LIU, Shuai TANG, Yuhong DONG

2017, 38(8):  1149-1158.  doi:10.1007/s10483-017-2224-9

Abstract ( 488 )   HTML   PDF (463KB) ( 148 )  

References | Related Articles | Metrics

The effect of inertial particles with different specific heat on heat transfer in particle-laden turbulent channel flows is studied using the direct numerical simulation (DNS) and the Lagrangian particle tracking method. The simulation uses a two-way coupling model to consider the momentum and thermal interactions between the particles and turbulence. The study shows that the temperature fields display differences between the particle-laden flow with different specific heat particles and the particle-free flow, indicating that the particle specific heat is an important factor that affects the heat transfer process in a particle-laden flow. It is found that the heat transfer capacity of the particle-laden flow gradually increases with the increase of the particle specific heat. This is due to the positive contribution of the particle increase to the heat transfer. In addition, the Nusselt number of a particle-laden flow is compared with that of a particle-free flow. It is found that particles with a large specific heat strengthen heat transfer of turbulent flow, while those with small specific heat weaken heat transfer of turbulent flow.

Response of turbulent enstrophy to sudden implementation of spanwise wall oscillation in channel flow

Mingwei GE, Guodong JIN

2017, 38(8):  1159-1170.  doi:10.1007/s10483-017-2226-9

Abstract ( 313 )   HTML   PDF (976KB) ( 76 )  

References | Related Articles | Metrics

The response of turbulent enstrophy to a sudden implementation of spanwise wall oscillation (SWO) is studied in a turbulent channel flow via direct numerical simulation. In the beginning of the application of SWO, a significant correlation is formed between ω'_y and ω'_z. A transient growth of turbulent enstrophy occurs, which directly enhances turbulent dissipation and drifts the turbulent flow towards a new lower-drag condition. Afterwards, the terms related to the stretching of vorticity (ωx, ω'_y, and ω_z), the inclination of ω'_y by ∂w/∂y, the turn of ω_z by ∂v'/∂z, and the horizontal shear of ω_z by ∂w'/∂x are suppressed due to the presence of SWO, leading to attenuation of the turbulent enstrophy.

Modeling natural convection boundary layer flow of micropolar nanofluid over vertical permeable cone with variable wall temperature

S. E. AHMED

2017, 38(8):  1171-1180.  doi:10.1007/s10483-017-2231-9

Abstract ( 546 )   HTML   PDF (799KB) ( 186 )  

References | Related Articles | Metrics

This paper discusses the natural convection boundary layer flow of a micropolar nanofluid over a vertical permeable cone with variable wall temperatures. Non-similar solutions are obtained. The nonlinearly coupled differential equations under the boundary layer approximations governing the flow are solved numerically using an efficient, iterative, tri-diagonal, implicit finite difference method. Different experimental correlations for both nanofluid effective viscosity and nanofluid thermal conductivity are considered. It is found that as the vortex-viscosity parameter increases, both the velocity profiles and the local Nusselt number decrease. Also, among all the nanoparticles considered in this investigation, Cu gives a good convection.

A class of epidemic virus transmission population dynamic system

Cheng OUYANG, Min ZHU, Jiaqi MO

2017, 38(8):  1181-1190.  doi:10.1007/s10483-017-2228-9

Abstract ( 377 )   HTML   PDF (196KB) ( 154 )  

References | Related Articles | Metrics

A class of epidemic virus transmission population dynamic system is considered. Firstly, using the functional homotopic analysis method, an initial approximate function is selected. Then, the arbitrary order approximate analytic solutions are obtained successively. Finally, the accuracy of the obtained approximate analytic solutions is described. The influence of the various physical parameters for the epidemic virus transmission population dynamic system is discussed.