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2021年 第42卷 第9期    刊出日期：2021-09-01

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论文

Size and temperature effects on band gaps in periodic fluid-filled micropipes

Jun HONG, Zhuangzhuang HE, Gongye ZHANG, Changwen MI

2021, 42(9):  1219-1232.  doi:10.1007/s10483-021-2769-8

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A new model is proposed for determining the band gaps of flexural wave propagation in periodic fluid-filled micropipes with circular and square thin-wall cross-sectional shapes, which incorporates temperature, microstructure, and surface energy effects. The band gaps depend on the thin-wall cross-sectional shape, the microstructure and surface elastic material constants, the pipe wall thickness, the unit cell length, the volume fraction, the fluid velocity in the pipe, the temperature change, and the thermal expansion coefficient. A systematic parametric study is conducted to quantitatively illustrate these factors. The numerical results show that the band gap frequencies of the current non-classical model with both circular and square thin-wall cross-sectional shapes are always higher than those of the classical model. In addition, the band gap size and frequency decrease with the increase of the unit cell length according to all the cases. Moreover, the large band gaps can be obtained by tailoring these factors.



Description of inverse energy cascade in homogeneous isotropic turbulence using an eigenvalue method

Feng LIU, Hantao LIU, Hongkai ZHAO, Pengfei LYU

2021, 42(9):  1233-1246.  doi:10.1007/s10483-021-2767-7

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A description of inverse energy cascade (from small scale to large scale) in homogeneous isotropic turbulence is introduced by using an eigenvalue method. We show a special isotropic turbulence, in which the initial condition is constructed by reversing the velocity field in space, i.e., the time-reversed turbulence. It is shown that the product of eigenvalues of the rate-of-strain tensor can quantitatively describe the backward energy transfer process. This description is consistent to the velocity derivative skewness S_k. However, compared with S_k, it is easier to be obtained, and it is expected to be extended to anisotropic turbulence. Furthermore, this description also works for the resolved velocity field, which means that it can be used in engineering turbulent flows. The description presented here is desired to inspire future investigation for the modeling of the backward energy transfer process and lay the foundation for the accurate prediction of complex flows.

Dynamics of Sutterby fluid flow due to a spinning stretching disk with non-Fourier/Fick heat and mass flux models

F. MABOOD, J. MACKOLIL, B. MAHANTHESH, A. RAUF, S. A. SHEHZAD

2021, 42(9):  1247-1258.  doi:10.1007/s10483-021-2770-9

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The magnetohydrodynamic Sutterby fluid flow instigated by a spinning stretchable disk is modeled in this study. The Stefan blowing and heat and mass flux aspects are incorporated in the thermal phenomenon. The conventional models for heat and mass flux, i.e., Fourier and Fick models, are modified using the Cattaneo-Christov (CC) model for the more accurate modeling of the process. The boundary layer equations that govern this problem are solved using the apt similarity variables. The subsequent system of equations is tackled by the Runge-Kutta-Fehlberg (RKF) scheme. The graphical visualizations of the results are discussed with the physical significance. The rates of mass and heat transmission are evaluated for the augmentation in the pertinent parameters. The Stefan blowing leads to more species diffusion which in turn increases the concentration field of the fluid. The external magnetism is observed to decrease the velocity field. Also, more thermal relaxation leads to a lower thermal field which is due to the increased time required to transfer the heat among fluid particles. The heat transport is enhanced by the stretching of the rotating disk.

A carbuncle cure for the Harten-Lax-van Leer contact (HLLC) scheme using a novel velocity-based sensor

U. S. VEVEK, B. ZANG, T. H. NEW

2021, 42(9):  1259-1278.  doi:10.1007/s10483-021-2762-6

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A hybrid numerical flux scheme is proposed by adapting the carbuncle-free modified Harten-Lax-van Leer contact (HLLCM) scheme to smoothly revert to the Harten-Lax-van Leer contact (HLLC) scheme in regions of shear. This hybrid scheme, referred to as the HLLCT scheme, employs a novel, velocity-based shear sensor. In contrast to the non-local pressure-based shock sensors often used in carbuncle cures, the proposed shear sensor can be computed in a localized manner meaning that the HLLCT scheme can be easily introduced into existing codes without having to implement additional data structures. Through numerical experiments, it is shown that the HLLCT scheme is able to resolve shear layers accurately without succumbing to the shock instability.

An analytic model for transient heat conduction in bi-layered structures with flexible serpentine heaters

Zhao ZHAO, Yuhang LI, Sujun DONG, Yi CUI, Zheng DAI

2021, 42(9):  1279-1296.  doi:10.1007/s10483-021-2765-9

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Uniform heating of complex surfaces, especially non-developable surfaces, is a crucial problem that traditional rigid heaters cannot solve. Inspired by flexible electronic devices, a novel design for the stretchable heating film is proposed with the flexible serpentine wire embedded in the soft polymer film, which can be attached to non-developable surfaces conformally. It provides a new way for the stretchable heaters to realize uniform heating of complex surfaces. However, the thermal field of flexible serpentine heaters (FSHs) depends on the configurations of the embedded serpentine heating wire, which requires accurate theoretical prediction of real-time temperature distribution. Therefore, the analytical model for the transient heat conduction in FSHs is solved by the separation of variables method and validated by the finite element analysis (FEA) in this paper. Based on this model, the effects of the geometric parameters, such as the radius and the length of the serpentine heaters, on the thermal uniformity are systematically investigated. This study can help to design and fabricate flexible heaters with uniform heating in the future.

Proper orthogonal decomposition analysis of coherent motions in a turbulent annular jet

Y. ZHANG, M. VANIERSCHOT

2021, 42(9):  1297-1310.  doi:10.1007/s10483-021-2764-8

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A three-dimensional incompressible annular jet is simulated by the large eddy simulation (LES) method at a Reynolds number Re=8 500. The time-averaged velocity field shows an asymmetric wake behind the central bluff-body although the flow geometry is symmetric. The proper orthogonal decomposition (POD) analysis of the velocity fluctuation vectors is conducted to study the flow dynamics of the wake flow. The distribution of turbulent kinetic energy across the three-dimensional POD modes shows that the first four eigenmodes each capture more than 1% of the turbulent kinetic energy, and hence their impact on the wake dynamics is studied. The results demonstrate that the asymmetric mean flow in the near-field of the annular jet is related to the first two POD modes which correspond to a radial shift of the stagnation point. The modes 3 and 4 involve the stretching or squeezing effects of the recirculation region in the radial direction. In addition, the spatial structure of these four POD eigenmodes also shows the counter-rotating vortices in the streamwise direction downstream of the flow reversal region.

Thomson effect with hyperbolic two-temperature on magneto-thermo-visco-elasticity

A. M. ALHARBI, M. I. A. OTHMAN, H. M. ATEF

2021, 42(9):  1311-1326.  doi:10.1007/s10483-021-2763-7

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The study considers a homogeneous isotropic thermo-visco-elastic solid with hyperbolic two-temperature to cope up with its two-dimensional (2D) deformations. The heat conduction equation is influenced by the Thomson coefficient. Lord-Shulman's theory is used to modify the basic governing equations. A method called "normal mode analysis" is utilized to attain the magnetic field, stress, conductive and thermodynamic temperature, and displacement components. Also, a number of numerical calculations are performed and discussed to understand the impact of hyperbolic two-temperatures, Thomson parameter, and viscosity on the material mentioned above.

Nonlinear stability of advanced sandwich cylindrical shells comprising porous functionally graded material and carbon nanotube reinforced composite layers under elevated temperature

H. V. TUNG, L. T. N. TRANG

2021, 42(9):  1327-1348.  doi:10.1007/s10483-021-2771-6

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The nonlinear stability of sandwich cylindrical shells comprising porous functionally graded material (FGM) and carbon nanotube reinforced composite (CNTRC) layers subjected to uniform temperature rise is investigated. Two sandwich models corresponding to CNTRC and FGM face sheets are proposed. Carbon nanotubes (CNTs) in the CNTRC layer are embedded into a matrix according to functionally graded distributions. The effects of porosity in the FGM and the temperature dependence of properties of all constituent materials are considered. The effective properties of the porous FGM and CNTRC are determined by using the modified and extended versions of a linear mixture rule, respectively. The basic equations governing the stability problem of thin sandwich cylindrical shells are established within the framework of the Donnell shell theory including the von Kármán-Donnell nonlinearity. These equations are solved by using the multi-term analytical solutions and the Galerkin method for simply supported shells. The critical buckling temperatures and postbuckling paths are determined through an iteration procedure. The study reveals that the sandwich shell model with a CNTRC core layer and relatively thin porous FGM face sheets can have the best capacity of thermal load carrying. In addition, unlike the cases of mechanical loads, porosities have beneficial effects on the nonlinear stability of sandwich shells under the thermal load. It is suggested that an appropriate combination of advantages of FGM and CNTRC can result in optimal efficiency for advanced sandwich structures.

Research on coupled thermo-hydro-mechanical dynamic response characteristics of saturated porous deep-sea sediments under vibration of mining vehicle

Wei ZHU, Xinyu SHI, Rong HUANG, Liyue HUANG, Wenbo MA

2021, 42(9):  1349-1362.  doi:10.1007/s10483-021-2768-5

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The excessive deformation of deep-sea sediments caused by the vibration of the mining machine will adversely affect the efficiency and safety of mining. Combined with the deep-sea environment, the coupled thermo-hydro-mechanical problem for saturated porous deep-sea sediments subject to the vibration of the mining vehicle is investigated. Based on the Green-Lindsay (G-L) generalized thermoelastic theory and Darcy's law, the model of thermo-hydro-mechanical dynamic responses for saturated porous deep-sea sediments under the vibration of the mining vehicle is established. We obtain the analytical solutions of non-dimensional vertical displacement, excess pore water pressure, vertical stress, temperature, and change in the volume fraction field with the normal mode analysis method, and depict them graphically. The normal mode analysis method uses the canonical coordinate transformation to solve the equation, which can quickly decouple the equation by ignoring the modal coupling effect on the basis of the canonical mode. The results indicate that the vibration frequency has obvious influence on the vertical displacement, excess pore water pressure, vertical stress, and change in volume fraction field. The loading amplitude has a great effect on the physical quantities in the foundation, and the changes of the physical quantities increase with the increase in loading amplitude.

Reflection of three-dimensional plane waves at the free surface of a rotating triclinic half-space under the context of generalized thermoelasticity

P. SINGH, A. K. SINGH, A. CHATTOPADHYAY

2021, 42(9):  1363-1378.  doi:10.1007/s10483-021-2766-6

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The reflection of three-dimensional (3D) plane waves in a highly anisotropic (triclinic) medium under the context of generalized thermoelasticity is studied. The thermoelastic nature of the 3D plane waves in an anisotropic medium is investigated in the perspective of the three-phase-lag (TPL), dual-phase-lag (DPL), Green-Naghdi-III (GN-III), Lord-Shulman (LS), and classical coupled (CL) theories. The reflection coefficients and energy ratios for all the reflected waves are obtained in a mathematical form. The rotational effects on the reflection characteristics of the 3D waves are discussed under the context of generalized thermoelasticity. Comparative analyses for the reflection coefficients of the waves among these generalized thermoelastic theories are performed. The energy ratios for each of the reflected waves establish the energy conservation law in the reflection phenomena of the plane waves. The highly anisotropic materials along with the rotation may have a significant role in the phenomenon of the reflection behavior of the 3D waves. Numerical computations are performed for the graphical representation of the study.