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MHD flow due to stretching sheet embedded in non Darcian porous medium with thermal stratification effects 具有热分层效应的非达西多孔介质中拉伸片引起的MHD流动
IF 1.8 Q3 ENGINEERING, MARINE Pub Date : 2018-06-28 DOI: 10.3329/jname.v15i1.29692
A. Banshiwal, M. Goyal
The aim of present study is to analyze the non- Darcian effects on unsteady non-linear MHD flow of an incompressible, electrically conducting and viscous fluid over a stretching sheet embedded in a porous medium with heat source, viscous dissipation and thermal stratification. The dimensionless governing equation solved numerically by using 4th order Runge - Kutta method. The effects of pertinent parameters on velocity and temperature depicted graphically.
本研究的目的是分析非达西效应对不可压缩、导电和粘性流体在具有热源、粘性耗散和热分层的多孔介质中嵌入的拉伸片上的非定常非线性MHD流动的影响。用四阶龙格-库塔方法数值求解了无量纲控制方程。相关参数对速度和温度的影响如图所示。
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引用次数: 0
Mathematical analysis of non-Newtonian nanofluid transport phenomena past a truncated cone with Newtonian heating 牛顿加热下非牛顿纳米流体通过截锥传输现象的数学分析
IF 1.8 Q3 ENGINEERING, MARINE Pub Date : 2018-06-28 DOI: 10.3329/JNAME.V15I1.29966
Nagendra Nallagundla, Ch. Amanulla, M. Reddy
In the present study, we analyze the heat, momentum and mass (species) transfer in external boundary layer flow of Casson nanofluid past a truncated cone surface with Biot Number effect is studied theoretically. The effects of Brownian motion and thermophoresis are incorporated in the model in the presence of both heat and nanoparticle mass transfer Biot Number effect. The governing partial differential equations (PDEs) are transformed into highly nonlinear, coupled, multi-degree non-similar partial differential equations consisting of the momentum, energy and concentration equations via. Appropriate non-similarity transformations. These transformed conservation equations are solved subject to appropriate boundary conditions with a second order accurate finite difference method of the implicit type. The influences of the emerging parameters i.e. Casson fluid parameter (?), Brownian motion parameter (Nb) and thermophoresis parameter (Nt), Lewis number (Le), Buoyancy ratio parameter (N ), Prandtl number (Pr) and Biot number (Bi) on velocity, temperature and nano-particle concentration distributions is illustrated graphically and interpreted at length.  Validation of solutions with a Nakamura tri-diagonal method has been included. The study is relevant to enrobing processes for electric-conductive nano-materials of potential use in aerospace and other industries.
在本研究中,我们分析了Casson纳米流体通过截锥表面的外边界层流动中的热、动量和质量(物种)传递,并从理论上研究了Biot数效应。布朗运动和热泳效应在存在热和纳米颗粒传质生物数效应的情况下被纳入模型中。通过将控制偏微分方程转化为由动量、能量和浓度方程组成的高度非线性、耦合、多阶非相似偏微分方程。适当的非相似性变换。这些变换后的守恒方程在适当的边界条件下用隐式二阶精确有限差分法求解。图中详细说明了新兴参数,即Casson流体参数(?)、布朗运动参数(Nb)和热泳参数(Nt)、Lewis数(Le)、浮力比参数(N)、普朗特数(Pr)和毕奥数(Bi)对速度、温度和纳米粒子浓度分布的影响。已包括使用Nakamura三对角线方法验证解决方案。该研究与在航空航天和其他行业具有潜在用途的导电纳米材料的包覆工艺有关。
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引用次数: 12
Natural convective flow in circular and arc cavities filled with water-cu nanofluid: a comparative study 水-铜纳米流体填充的圆形和弧形腔内自然对流的比较研究
IF 1.8 Q3 ENGINEERING, MARINE Pub Date : 2018-06-28 DOI: 10.3329/JNAME.V15I1.33549
K. F. U. Ahmed, R. Nasrin, M. Elias
The fluid flow and heat transfer mechanism on steady state solutions obtained in circular and arc-square enclosures filled with water/Cu nanofluid as well as base fluid has been investigated numerically by Galerkin's weighted residual finite element procedure. The left and right boundaries of the cavities are, respectively, heated and cooled at constant temperatures, while their horizontal walls are adiabatic. Effects of buoyancy force (Rayleigh number) and viscous force (Prandtl number) with a wide range of Ra (103 - 106) and Pr (4.2 - 6.2) on heat transfer phenomenon inside cavities are observed. The fluid flow and temperature gradient are shown by streamlines and isotherms patterns. From the investigation, it is reported that the Rayleigh and Prandtl numbers are playing significant role in heat transfer rate. The variation in heat transfer is calculated in terms of average Nusselt number. Heat transfer rate is found to be higher for water/Cu nanofluid with 2% solid volume fraction than pure water. About 2.7% higher heat transfer rate is obtained for circular cavity than that of arc cavity using water/Cu nanofluid at Ra = 104 and Pr = 5.8.
采用Galerkin加权残差有限元方法,对充水/铜纳米流体和基底流体的圆形和弧形方形外壳中稳态解的流体流动和传热机制进行了数值研究。空腔的左边界和右边界分别在恒定温度下加热和冷却,而它们的水平壁是绝热的。观察了浮力(瑞利数)和粘性力(普朗特数)在Ra(103-106)和Pr(4.2-6.2)宽范围内对空腔内传热现象的影响。流体流动和温度梯度通过流线和等温线模式显示。研究表明,瑞利数和普朗特数对传热速率起着重要作用。传热的变化是根据平均努塞尔数来计算的。固体体积分数为2%的水/Cu纳米流体的传热速率高于纯水。在Ra=104和Pr=5.8时,圆形腔的传热率比使用水/Cu纳米流体的弧形腔高出约2.7%。
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引用次数: 8
Ultimate strength formulation of stiffened panels under in-plane compression or tension with cracking damage 带裂纹损伤的平面内压缩或拉伸加筋板的极限强度公式
IF 1.8 Q3 ENGINEERING, MARINE Pub Date : 2018-06-28 DOI: 10.3329/JNAME.V15I1.31668
M. Zareei, M. Iranmanesh
The aim of the present study is to develop closed-form formulations for predicting the ultimate compressive and tensional strength of stiffened steel panels with crack damages. First, a numerical database is generated. This database includes the ultimate strength levels of stiffened steel panels with cracks subjected to axial compressive or tensile loads. It was carried out with a series of nonlinear FEM analyses by varying the size of crack damage. In the following sections, regression analysis is used for deriving the empirical formulations. The results of the present paper can be used for the reliability and risk assessment of structures, including stiffened steel panels with cracks. 
本研究的目的是开发用于预测具有裂纹损伤的加筋钢板的极限抗压和抗拉强度的闭合公式。首先,生成一个数字数据库。该数据库包括在轴向压缩或拉伸载荷作用下具有裂纹的加筋钢板的极限强度水平。通过改变裂纹损伤的大小,进行了一系列非线性有限元分析。在以下各节中,回归分析用于推导经验公式。本文的结果可用于结构的可靠性和风险评估,包括带裂纹的加筋钢板。
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引用次数: 2
Computational hydrodynamic analysis of a highly skewed marine propeller 大偏斜船用螺旋桨的计算水动力分析
IF 1.8 Q3 ENGINEERING, MARINE Pub Date : 2018-06-19 DOI: 10.20944/preprints201806.0307.v1
Houari Hussein, K. Boumediene, S. E. Belhenniche, O. Imine, M. Bouzit
 The objective of the current paper is to study the flow around Seiun Maru Highly Skewed (HSP) marine propeller by assessment of blade forces and moments under non-cavitating case. The calculations are performed in open water (steady case) and non-uniform ship wake (Unsteady case). The governing equations based on Reynolds Averaged Navier-Stokes Equation (RANSE) are solved using Finite Volume Method. Ansys Fluent 14.0 is used to implement the simulation. For the steady case, Moving Reference Frame (MRF) is selected while sliding mesh technique is adopted for the unsteady case. Calculated open water performances in terms of thrust and torque coefficients fit very well with experimental data for a wide range of advance ratio. In the unsteady calculations, axial velocities, deduced from the nominal wake, are introduced in the Ansys fluent code. To locate suitably the non-uniform wake in the propeller front plane, three positions of inlet wake have been taken into account to determine their effects on the accuracy of the results. Obtained results show that computed performances are improved compared to panel method when the inlet is close to the propeller.  
本文的目的是通过评估无空化情况下的叶片力和力矩来研究Seiun Maru高倾斜(HSP)船用螺旋桨周围的流动。计算是在开放水域(稳定情况)和非均匀船舶尾流(非稳定情况)下进行的。采用有限体积法求解了基于雷诺平均Navier-Stokes方程的控制方程。Ansys Fluent 14.0用于实现仿真。对于稳定情况,选择移动参考系(MRF),而对于非稳定情况,则采用滑动网格技术。根据推力和扭矩系数计算的开放水域性能与大范围推进比的实验数据非常吻合。在非定常计算中,在Ansys fluent程序中引入了从标称尾流推导出的轴向速度。为了适当地定位螺旋桨前平面中的非均匀尾流,考虑了三个入口尾流位置,以确定它们对结果准确性的影响。计算结果表明,当进气道靠近螺旋桨时,与面板法相比,计算性能有所提高。
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引用次数: 3
A molecular dynamic study of change in thermodynamic functions of silicon FCC cell with the change in temperature 硅催化裂化电池热力学函数随温度变化的分子动力学研究
IF 1.8 Q3 ENGINEERING, MARINE Pub Date : 2017-12-28 DOI: 10.3329/JNAME.V14I2.30128
A. Bari, S. Rubaiee, Anas Ahmed, A. Masud
In modern days silicon is being extensively used in making electronic semiconductor-based chips and IC’s. In this research, the change in different thermodynamic properties of silicon like lattice heat capacity, molar enthalpy and Debye temperature at constant pressure, with the change in temperature, has been investigated by using molecular dynamics (MD) simulation method. Knowing silicon’ thermodynamic functions are quite important, because many electronic companies are nowadays trying a lot to reduce the heat generated by their semiconductor chips as excessive heating of the chip not only warms up the device quickly but also reduces the chip life. The results obtained from this simulation help engineers to design electronic chips more efficiently. For simulation “Accelrys Materials Studio” (Version 5.0) software has been used. The simulation was run for silicon FCC diamond structured cell. The analysis tool used in the simulation is known as CASTEP (Cambridge Sequential Total Energy Package). This tool is specialized for performing molecular level thermodynamic analysis to generate data and graphs for the change in different temperature dependent properties of the molecular system. The interaction between silicon atoms was expressed by the Kohn-Sham potential and MD calculation was conducted on crystalline state of silicon at temperatures between 0 and 1000 K. Here, density function theory (DFT) based tool has been used to derive density of state relations. Results obtained by the simulation were compared with published experimental values and it was found that the simulation results were close to the experimental values.
在现代,硅被广泛用于制造电子半导体芯片和集成电路。本研究采用分子动力学(MD)模拟方法,研究了恒压下硅的晶格热容、摩尔焓和德拜温度等不同热力学性质随温度变化的变化规律。了解硅的热力学功能是非常重要的,因为现在许多电子公司都在努力减少半导体芯片产生的热量,因为芯片的过度加热不仅会使设备迅速升温,而且会缩短芯片的寿命。仿真结果有助于工程师更有效地设计电子芯片。模拟“Accelrys Materials Studio”(5.0版)软件已被使用。对硅FCC金刚石结构电池进行了仿真。模拟中使用的分析工具被称为CASTEP(剑桥顺序总能量包)。该工具是专门用于执行分子水平热力学分析,以生成数据和图表的变化,在不同的温度依赖的性质的分子系统。硅原子间的相互作用用Kohn-Sham势表示,并对0 ~ 1000 K温度下硅的晶态进行了MD计算。本文采用密度函数理论(DFT)来推导状态关系的密度。将仿真结果与已发表的实验值进行了比较,发现仿真结果与实验值接近。
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引用次数: 0
Numerical analysis of heat and mass transfer along a stretching wedge surface 拉伸楔表面传热传质的数值分析
IF 1.8 Q3 ENGINEERING, MARINE Pub Date : 2017-12-28 DOI: 10.3329/JNAME.V14I2.30633
M. Ali, M. A. Alim, R. Nasrin, M. Alam
In this work, the effects of dimensionless parameters on the velocity field, thermal field and nanoparticle concentration have been analyzed. In this respect, the magnetohydrodynamic (MHD) boundary layer nanofluid flow along a moving wedge is considered. Therefore, a similarity solution has been derived like Falkner – Skan solution and identified the point of inflexion. So the governing partial differential equations transform into ordinary differential equations by using the similarity transformation. These ordinary differential equations are numerically solved using fourth order Runge–Kutta method along with shooting technique. The present results have been shown graphically and in tabular form. From the graph, the results indicate that the velocity increases with increasing values of pressure gradient, magnetic induction and velocity ratio. The temperature decreases for velocity ratio, Brownian motion and Prandtl number but opposite result arises for increasing values of thermophoresis. The nanoparticle concentration decreases with an increase in pressure gradient, Brownian motion and Lewis number, but increases for thermophoresis. Besides, the solution of nanoparticle concentration exists in the case of Brownian motion is less than 0.2, thermophoresis is less than 0.14 and lewis number is greater than 1.0. Finally, for validity and accuracy the present results have been compared with previous work and found to be in good agreement.
本文分析了无量纲参数对速度场、热场和纳米颗粒浓度的影响。在这方面,考虑了磁流体动力学(MHD)边界层纳米流体沿着移动楔的流动。因此,类似Falker-Skan解的相似解被推导出来,并确定了拐点。因此,利用相似变换将控制偏微分方程转化为常微分方程。这些常微分方程是用四阶龙格-库塔方法和射击技术数值求解的。结果表明,随着压力梯度、磁感应和速比的增大,速度增大。温度随着速度比、布朗运动和普朗特数的增加而降低,但随着热泳值的增加而出现相反的结果。纳米颗粒浓度随着压力梯度、布朗运动和路易斯数的增加而降低,但随着热泳的增加而增加。此外,在布朗运动小于0.2、热泳小于0.14和路易斯数大于1.0的情况下,存在纳米颗粒浓度的溶液。最后,为了验证有效性和准确性,将目前的结果与以前的工作进行了比较,结果一致。
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引用次数: 9
Numerical simulation of vortex induced vibration in heat exchanger tube bundle at low Reynolds number 低雷诺数下换热器管束涡激振动数值模拟
IF 1.8 Q3 ENGINEERING, MARINE Pub Date : 2017-12-28 DOI: 10.3329/JNAME.V14I2.25894
Asif Khan, S. Khushnood, N. Saqib, I. Shahid
It is sound recognized that when the tube is forced to vibrate or is naturally excited to sufficient amplitudes by flow-induced forces, cyclones peeling phenomena arises at downstream of a tube which clues to vibration in the tube. Two-dimensional numerical recreation model for the computation of flow induced vibration of heat exchanger tube bundle imperiled to cross- flow is proficient in current research. Computational Fluid Dynamics (CFD) tool, GAMBIT (grid generation) and ANSYS FLUENT (fluid flow analysis) are operated during numerical investigations. k-epsilon model is used to solve the Navier– Stokes equations. Lift coefficient graph derived from analysis is used to predict the vortex shedding frequency using Fast Fourier Transform (FFT). The results of flow rate, Strouhal number, Reduced velocity, Natural frequency of tube as found from the experimental data has been verified numerically for a Reynolds number range of 4.45 × 104
人们已经认识到,当管道被迫振动或被流体诱导力自然激发到足够的振幅时,旋风分离器剥离现象会在管道下游出现,这表明管道中存在振动。用二维数值重建模型计算有交叉流危险的换热器管束的流激振动是目前研究的热点。在数值研究过程中,使用了计算流体动力学(CFD)工具、GAMBIT(网格生成)和ANSYS FLUENT(流体流动分析)。ε模型用于求解Navier-Stokes方程。通过分析得出的升力系数图用于使用快速傅立叶变换(FFT)预测旋涡脱落频率。在雷诺数为4.45×104<Re<4.65×104的情况下,对实验数据中的流量、斯特劳哈尔数、降速和管固有频率的结果进行了数值验证。结果表明,实验结果和数值计算结果吻合较好。
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引用次数: 1
Wave interaction with Floating platform of different shapes and supports using BEM approach 基于边界元法的波浪与不同形状和支撑的浮动平台的相互作用
IF 1.8 Q3 ENGINEERING, MARINE Pub Date : 2017-12-28 DOI: 10.3329/JNAME.V14I2.28267
A. Shirkol, Nasar Thuvanismail
Wave interaction with a floating thin elastic plate which can be used as floating platform is analyzed using Boundary Element Method (BEM) for different shapes such as rectangular, circular and triangular. Different support conditions are considered and the performance of the floating platform under the action of ocean waves is explored. The study is performed under the assumption of linearized water wave theory and the floating elastic plate is modelled based on the Euler-Bernoulli beam theory. Using Galerkin’s approach, a numerical model has been developed and the hydrodynamic loading on the floating elastic plate of shallow draft (thickness) is investigated. The wave forces are generated by the numerical model for the analysis of the floating plate. The resulting bending moment and optimal deflection due to encountering wave force is analysed. The present study will be helpful in design and analysis of the large floating platform in ocean waves.
采用边界元法分析了波浪与可作为浮动平台的弹性薄板的相互作用,分析了不同形状的矩形、圆形和三角形弹性薄板的相互作用。考虑了不同的支撑条件,探讨了浮动平台在海浪作用下的性能。在线性化水波理论的假设下,浮动弹性板采用欧拉-伯努利梁理论进行建模。采用伽辽金方法建立了数值模型,研究了浅吃水(厚度)浮动弹性板的水动力载荷。波浪力是由浮板分析的数值模型产生的。分析了波浪力作用下的弯矩和最优挠度。本文的研究成果对大型海上浮式平台的设计与分析具有一定的指导意义。
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引用次数: 0
Heat and mass transfer with viscous dissipation in horizontal channel partially occupied by porous medium in the presence of oscillatory suction 振荡吸力作用下部分被多孔介质占据的水平通道中具有粘性耗散的传热传质
IF 1.8 Q3 ENGINEERING, MARINE Pub Date : 2017-12-28 DOI: 10.3329/JNAME.V14I2.25584
P. Sharma, R. Saboo
This paper deals with unsteady oscillatory flow of viscous incompressible fluid with heat & mass transfer in a horizontal channel partially occupied by porous medium following the Darcy-Brinkman model. The interior territory of the channel consists of two regions; one of them is filled with porous material and second is clear fluid. At the porous medium fluid interface, interfacial coupling conditions for the fluid velocity, temperature and concentration were used to derive the analytical solution. The effects of pertinent physical fluid parameter like porosity, viscosity ratio, density ratio etc. on velocity, temperature and concentration distribution are considered and demonstrated through graphs. Also, the non-dimensional Skin-friction coefficient, Nusselt number and Sherwood number have been calculated and reported in tabular form.
本文采用Darcy-Brinkman模型,研究了部分由多孔介质占据的水平通道中具有传热传质的粘性不可压缩流体的非定常振荡流动。海峡内部由两个区域组成;其中一个是用多孔材料填充的,第二个是透明流体。在多孔介质-流体界面上,利用流体速度、温度和浓度的界面耦合条件导出了解析解。考虑了孔隙度、粘度比、密度比等相关物理流体参数对速度、温度和浓度分布的影响,并通过图形进行了论证。此外,还计算了无量纲皮肤摩擦系数、努塞尔数和舍伍德数,并以表格形式报告。
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引用次数: 5
期刊
Journal of Naval Architecture and Marine Engineering
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