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Implicit Finite Difference Simulation of Hybrid Nanofluid along a Vertical Thin Cylinder with Sinusoidal Wall Heat Flux under the Effects of Magnetic Field 磁场效应下具有正弦壁面热通量的垂直薄圆柱混合纳米流体的隐式有限差分模拟
IF 1.2 4区 物理与天体物理 Q3 PHYSICS, MATHEMATICAL Pub Date : 2023-12-22 DOI: 10.1155/2023/6699888
Mashiyat Khan, Amzad Hossain, Afroja Parvin, M. Molla
A numerical analysis of magnetohydrodynamic natural convection along a thin vertical cylinder with a sinusoidal heat flux at the wall immersed in copper (Cu) and aluminum-oxide (Al2O3) hybrid nanofluids has been studied. A 2D vertical thin cylinder shape geometry has been considered with a radius of R. The fluid flow is considered laminar and incompressible with the Prandtl number of Pr = 6.2 and 10% concentration of hybrid nanoparticles. The nondimensional governing equations have been solved numerically by using the implicit finite difference method. An in-house FORTRAN 90 code is used for solving this problem and the code is validated with the available benchmark results. Numerical simulations have been performed for a wide range of governing parameters, Hartmann number from Ha = 0 to Ha = 4, nanoparticles volume fractions ϕ = 0.0 to ϕ = 0.1, and the amplitude of the wall heat flux ε = 0.0–0.3. The findings have been illustrated in terms of streamlines, isotherms, local skin friction coefficients, local Nusselt numbers, velocity, and temperature distributions. The flow field and temperature distribution within the boundary layer are deceased by the effects of the wall heat flux amplitudes. It is also noted that the rate of heat transfer increases with particle volume fraction and the amplitude of the wall heat flux. According to the findings, Nu increases by 24.72% as ϕ increases from 0 to 0.1 while ε = 0.3, and 27.66% while ε increases from 0.0 to 0.3 at 5% hybrid nanoparticles. The local skin frictions and Nusselt number diminish with the increment of the Hartman number due to the effects of the Lorenz force. The findings of this study can lead to a better understanding of the fundamental principles regarding the behavior of hybrid nanofluids under complex conditions, such as a vertical thin cylinder with a sinusoidal wall heat flux. Understanding the behavior of hybrid nanofluids in the presence of a magnetic field and a nonuniform wall heat flow can also lead to the development of innovative heat transfer enhancement strategies.
研究人员对浸入铜(Cu)和氧化铝(Al2O3)混合纳米流体的垂直薄圆柱体进行了磁流体力学自然对流的数值分析。研究考虑了半径为 R 的二维垂直薄圆柱体几何形状。流体流动为层流,不可压缩,普朗特数为 Pr = 6.2,混合纳米粒子浓度为 10%。采用隐式有限差分法对无量纲控制方程进行数值求解。内部使用的 FORTRAN 90 代码用于解决该问题,并用现有的基准结果对该代码进行了验证。数值模拟的调节参数范围很广,哈特曼数从 Ha = 0 到 Ha = 4,纳米颗粒体积分数 ϕ = 0.0 到 ϕ = 0.1,壁面热通量振幅 ε = 0.0-0.3 。研究结果通过流线、等温线、局部表皮摩擦系数、局部努塞尔特数、速度和温度分布进行了说明。边界层内的流场和温度分布受到壁面热通量振幅的影响。研究还发现,传热速率随颗粒体积分数和壁面热通量振幅的增加而增加。根据研究结果,当 ε = 0.3 时,ϕ 从 0 增加到 0.1,Nu 增加了 24.72%;当 ε 从 0.0 增加到 0.3 时,Nu 增加了 27.66%。由于洛伦兹力的影响,局部表皮摩擦和努塞尔特数随着哈特曼数的增大而减小。本研究的发现有助于更好地理解混合纳米流体在复杂条件下(如具有正弦壁面热通量的垂直薄圆柱体)的行为的基本原理。了解混合纳米流体在磁场和非均匀壁面热流作用下的行为还有助于开发创新的传热增强策略。
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引用次数: 0
Retracted: A Cloud Computing-Based Intelligent Forecasting Method for Cross-Border E-Commerce Logistics Costs 撤回:基于云计算的跨境电商物流成本智能预测方法
IF 1.2 4区 物理与天体物理 Q3 PHYSICS, MATHEMATICAL Pub Date : 2023-12-20 DOI: 10.1155/2023/9834121
Advances in Mathematical Physics
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引用次数: 0
Retracted: Research on Spectrum Feature Identification of Indoor Multimodal Communication Signal 撤回:室内多模态通信信号的频谱特征识别研究
IF 1.2 4区 物理与天体物理 Q3 PHYSICS, MATHEMATICAL Pub Date : 2023-12-20 DOI: 10.1155/2023/9848035
Advances in Mathematical Physics
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引用次数: 0
Retracted: Study on Announcement Effect of Stock Repurchase from the Perspective of Configuration Analysis 撤回:配置分析视角下的股票回购公告效应研究
IF 1.2 4区 物理与天体物理 Q3 PHYSICS, MATHEMATICAL Pub Date : 2023-12-20 DOI: 10.1155/2023/9836215
Advances in Mathematical Physics
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引用次数: 0
Retracted: Asymptotic Behavior of Solution for Functional Evolution Equations with Stepanov Forcing Terms 撤回:带有斯捷潘诺夫强迫项的函数演化方程求解的渐近行为
IF 1.2 4区 物理与天体物理 Q3 PHYSICS, MATHEMATICAL Pub Date : 2023-12-20 DOI: 10.1155/2023/9816201
Advances in Mathematical Physics
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引用次数: 0
Modelling and Investigation of the Dynamic Behavior of a Penny-Shaped Interface Crack in Piezoelectric Bimaterials 压电双材料中竹篙形界面裂缝的动态行为建模与研究
IF 1.2 4区 物理与天体物理 Q3 PHYSICS, MATHEMATICAL Pub Date : 2023-12-19 DOI: 10.1155/2023/6660484
Yani Zhang, Junlin Li, Di Liu, Xiufeng Xie
In this section, the dynamic propagation behavior of a penny-shaped interface crack in piezoelectric bimaterials is analyzed. The objective of this paper is to use the boundary conditions of the penny-shaped interface crack to study the dynamic propagation of the crack under the action of load, so as to provide some valuable implications for the fracture mechanics of the piezoelectric bimaterials and simulate the interface crack between piezoelectric bimaterials, it is necessary to establish a suitable model and give appropriate boundary conditions according to the actual situation. The elastic displacement and potential equations are constructed according to the structural characteristics of the circular crack. In the case of a given displacement or stress, the Laplace transform and Hankel transform are used to simplify the problem into an integral equation with unknown functions. According to the boundary conditions, the corresponding unknowns are obtained, and the closed solution is derived. The results show that the fracture toughness of a penny-shaped interface crack in piezoelectric bimaterials is related to the thickness of the material, the impact time, the material characteristics, and the electric field. At the same time, it can be found that different materials have different roles in the crack propagation, so it is very important to study the crack opening displacement (COD) intensity factor of the crack for safety design.
本节分析了压电双材料中一分钱形界面裂纹的动态扩展行为。本文的目的是利用一分钱形界面裂纹的边界条件研究裂纹在载荷作用下的动态扩展,从而为压电双材料的断裂力学提供一些有价值的启示,模拟压电双材料之间的界面裂纹,需要根据实际情况建立合适的模型并给出合适的边界条件。根据圆形裂缝的结构特征构建弹性位移和位势方程。在给定位移或应力的情况下,利用拉普拉斯变换和汉克尔变换将问题简化为带未知函数的积分方程。根据边界条件,得到相应的未知数,并推导出闭合解。结果表明,压电双材料中的一分钱形界面裂纹的断裂韧性与材料厚度、冲击时间、材料特性和电场有关。同时,可以发现不同材料在裂纹扩展中的作用不同,因此研究裂纹的开裂位移(COD)强度因子对于安全设计非常重要。
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引用次数: 0
Spectral Element Method for Fractional Klein–Gordon Equations Using Interpolating Scaling Functions 使用插值缩放函数的分数克莱因-戈登方程谱元法
IF 1.2 4区 物理与天体物理 Q3 PHYSICS, MATHEMATICAL Pub Date : 2023-12-12 DOI: 10.1155/2023/8453459
Haifa Bin Jebreen
The focus of this paper is on utilizing the spectral element method to find the numerical solution of the fractional Klein–Gordon equation. The algorithm employs interpolating scaling functions (ISFs) that meet specific properties and satisfy the multiresolution analysis. Using an orthonormal projection, the equation is mapped to the scaling spaces in this method. A matrix representation of the Caputo fractional derivative of ISFs is presented using matrices representing the fractional integral and derivative operators. Using this matrix, the spectral element method reduces the desired equation to a system of algebraic equations. To find the solution, the generalized minimal residual method (GMRES method) and Newton’s method are used in linear and nonlinear forms of this system, respectively. The method’s convergence is proven, and some illustrative examples confirm it. The method is characterized by its simplicity in implementation, high efficiency, and significant accuracy.
本文的重点是利用谱元法求分数克莱因-戈登方程的数值解。该算法采用符合特定属性并满足多分辨率分析的插值缩放函数 (ISF)。利用正交投影,该方法可将方程映射到缩放空间。利用表示分数积分和导数算子的矩阵,提出了 ISF 的卡普托分数导数矩阵表示法。利用该矩阵,谱元法可将所需方程还原为代数方程系。为了求解,在该系统的线性和非线性形式中分别使用了广义最小残差法(GMRES 法)和牛顿法。该方法的收敛性已得到证明,一些示例也证实了这一点。该方法的特点是实施简单、效率高、精度高。
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引用次数: 0
Free Convection Heat Transfer in Composite Enclosures with Porous and Nanofluid Layers 多孔层和纳米流体层复合围护结构中的自由对流传热
IF 1.2 4区 物理与天体物理 Q3 PHYSICS, MATHEMATICAL Pub Date : 2023-12-11 DOI: 10.1155/2023/2088607
Abeer Alhashash
This work conducts a numerical investigation of convection heat transfer within two composite enclosures. These enclosures consist of porous and nanofluidic layers, where the porous layers are saturated with the same nanofluid. The first enclosure has two porous layers of different sizes and permeabilities, while the second is separated by a single porous layer. As the porous layer thickness approaches zero, both enclosures transition to clear nanofluid enclosures. The study uses the Navier–Stokes equations to govern fluid flow in the nanofluid domain and the Brinkman–Forchheimer extended Darcy model to describe flow within the saturated porous layer. Numerical solutions are obtained using an iterative finite difference method. Key parameters studied include the porous thickness (<span><svg height="9.75571pt" style="vertical-align:-1.11981pt" version="1.1" viewbox="-0.0498162 -8.6359 26.707 9.75571" width="26.707pt" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><g transform="matrix(.013,0,0,-0.013,0,0)"></path></g><g transform="matrix(.013,0,0,-0.013,6.24,0)"></path></g><g transform="matrix(.013,0,0,-0.013,9.204,0)"><use xlink:href="#g113-49"></use></g><g transform="matrix(.013,0,0,-0.013,19.076,0)"></path></g></svg><span></span><svg height="9.75571pt" style="vertical-align:-1.11981pt" version="1.1" viewbox="30.2891838 -8.6359 17.399 9.75571" width="17.399pt" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><g transform="matrix(.013,0,0,-0.013,30.339,0)"></path></g><g transform="matrix(.013,0,0,-0.013,40.107,0)"><use xlink:href="#g117-93"></use></g></svg><span></span><span><svg height="9.75571pt" style="vertical-align:-1.11981pt" version="1.1" viewbox="51.320183799999995 -8.6359 15.739 9.75571" width="15.739pt" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><g transform="matrix(.013,0,0,-0.013,51.37,0)"></path></g><g transform="matrix(.013,0,0,-0.013,57.61,0)"><use xlink:href="#g113-47"></use></g><g transform="matrix(.013,0,0,-0.013,60.574,0)"><use xlink:href="#g113-49"></use></g></svg>),</span></span> the nanoparticle volume fraction (<span><svg height="12.3916pt" style="vertical-align:-3.42948pt" version="1.1" viewbox="-0.0498162 -8.96212 26.707 12.3916" width="26.707pt" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><g transform="matrix(.013,0,0,-0.013,0,0)"><use xlink:href="#g113-49"></use></g><g transform="matrix(.013,0,0,-0.013,6.24,0)"><use xlink:href="#g113-47"></use></g><g transform="matrix(.013,0,0,-0.013,9.204,0)"><use xlink:href="#g113-49"></use></g><g transform="matrix(.013,0,0,-0.013,19.076,0)"><use xlink:href="#g117-93"></use></g></svg><span></span><svg height="12.3916pt" style="vertical-align:-3.42948pt" version="1.1" viewbox="30.2891838 -8.96212 18.609 12.3916" width="18.609pt" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><g transform="matrix(.013,0,0,-0.013,30.339,0)"></path>
本研究对两个复合围护结构内的对流传热进行了数值研究。这些外壳由多孔层和纳米流体层组成,多孔层中饱含相同的纳米流体。第一个外壳有两个大小和渗透率不同的多孔层,而第二个外壳由一个多孔层隔开。当多孔层厚度趋近于零时,两个外壳都会过渡到透明的纳米流体外壳。研究使用纳维-斯托克斯方程来控制纳米流体域中的流体流动,并使用布林克曼-福克海默扩展达西模型来描述饱和多孔层内的流动。数值求解采用迭代有限差分法。研究的主要参数包括多孔厚度()、纳米粒子体积分数()、导热比()和达西数()。主要发现包括:无论多孔层构造、渗透率值或导热率如何,在最高浓度时都能实现最高传热。具体来说,当浓度从 1%调整到 5%时,传热值最多可增加 22%。同样,当浓度从 1%调整到 5%时,数值最多可增加 25%。
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引用次数: 0
QMU Analysis of Flexoelectric Timoshenko Beam by Evidence Theory 基于证据理论的柔性电Timoshenko梁QMU分析
IF 1.2 4区 物理与天体物理 Q3 PHYSICS, MATHEMATICAL Pub Date : 2023-12-02 DOI: 10.1155/2023/2967408
Feng Zhang, Jiajia Zhang, Weiyue Wang, Ruijie Du, Cheng Han, Zijie Qiao
In recent years, with the rapid development of nanotechnology, a new type of electromechanical coupling effect similar to the piezoelectric effect, the flexoelectric effect, has gradually come into the public’s view. The flexoelectric beam that is the main structural unit of the flexoelectric signal output has broad application prospects in the next generation of micro- and nanoelectromechanical systems. Therefore, the investigation of flexoelectric materials and structures has important scientific and engineering application significances for the design of flexoelectric devices. In this paper, a model of flexoelectric Timoshenko beam is established, the deflection, rotation angle, and dynamic electrical signal output of the forced vibration are taken as the system response, and the density , shear correction factor , and frequency ratio are selected as the key performance parameters of the system. The combination of available data and engineers’ experience suggests that there are random and cognitive uncertainties in the parameters. Therefore, the probability distribution of the system performance response is expressed by the likelihood function and belief function through the quantification of margins and uncertainties (QMUs) analysis methodology under the framework of evidence theory, and the system reliability or performance evaluation is measured by the calculated confidence factors. These results provide a theoretical basis for accurate analysis of flexoelectric components and provide guidance for the design of flexoelectric components with excellent performance.
近年来,随着纳米技术的飞速发展,一种类似于压电效应的新型机电耦合效应——挠电效应逐渐进入人们的视野。挠曲电子束作为挠曲电信号输出的主要结构单元,在下一代微纳机电系统中具有广阔的应用前景。因此,研究柔性电材料和结构对柔性电器件的设计具有重要的科学和工程应用意义。本文建立了挠性电Timoshenko梁的模型,将受迫振动的挠度、转角和动态电信号输出作为系统响应,选择密度、剪切修正系数和频率比作为系统的关键性能参数。现有数据和工程师经验的结合表明,参数中存在随机和认知的不确定性。因此,在证据理论的框架下,通过量化边际和不确定性(QMUs)分析方法,用似然函数和信念函数来表示系统性能响应的概率分布,并通过计算得到的置信因子来衡量系统的可靠性或性能评价。这些结果为柔性电气元件的精确分析提供了理论依据,并为设计性能优良的柔性电气元件提供了指导。
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引用次数: 0
Effects of Soret and Dufour on Unsteady Magneto-Convective Transport through a Vertical Perforated Sheet with Chemical Reaction Soret和Dufour对具有化学反应的垂直穿孔板非定常磁对流输运的影响
IF 1.2 4区 物理与天体物理 Q3 PHYSICS, MATHEMATICAL Pub Date : 2023-12-02 DOI: 10.1155/2023/6648797
Md. Mosharrof Hossain, Md. Hasanuzzaman, A. Rahim Laskar, Ashish Barmon
An investigation of the effects of Soret and Dufour on an unsteady MHD convective transmission over a vertical porous sheet with chemical reaction was introduced throughout this study. The model that formed nonlinear governing equations is transformed by applying the similarity analysis with the help of the finite difference method. The numerical resolutions of the fluid characteristics like velocity, concentration, and temperature are explained graphically. This research also presented the mass transmission rate, heat transmission rate, and the local skin friction coefficient, which are explained in tabular form. The results give the fluid motion and temperature improvement for growing values of the Dofour effect. Also, the fluid velocity and concentration improve for elevated amounts of the Soret effect. The local skin friction improves by around 66% whereas the mass transmission rate lessens by around 247% with the growing Soret number (0.5–2.0).
研究了Soret和Dufour对具有化学反应的垂直多孔板上非定常MHD对流传输的影响。在有限差分法的帮助下,应用相似度分析对形成非线性控制方程的模型进行了变换。流体特性如速度、浓度和温度的数值分辨率用图形解释。本研究还给出了传质率、传热率和局部表面摩擦系数,并以表格形式进行了解释。结果表明,流体运动和温度的提高对Dofour效应的增长值有促进作用。此外,流体的速度和浓度也会随着Soret效应的增加而提高。随着Soret数(0.5-2.0)的增加,局部皮肤摩擦提高约66%,质量传播率降低约247%。
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引用次数: 0
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Advances in Mathematical Physics
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