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URANS Prediction of the Hydrodynamic Interactions of Two Ship-like Floating Structures in Regular Waves 规则波浪中两个类船漂浮结构的水动力相互作用的 URANS 预测
Q2 Mathematics Pub Date : 2024-07-21 DOI: 10.37934/cfdl.16.12.117
Fahmy Ardhiansyah, Rudi W Prastianto, Eko Budi Djatmiko, Ketut Suastika
A side-by-side configuration of floating structures is commonly used in ocean exploration practices, such as offshore vessels for loading and offloading, floating cranes, and offshore floating wind turbines. Computational Fluid Dynamics (CFD) method is current practice for the analysis of hydrodynamic interactions of the side-by-side vessels. The purpose of this study is yo carry out a benchmark study of CFD method applied for the above analysis. URANS CFD method was applied utilizing a k-ε turbulence model and a volume of fluid (VOF) method to capture the free surface. Different ratios of wave length to vessel’s length and different gaps between between the vessels were considered in the study. Simulation results show that the wave length to vessel’s length ratio /L affects significantly the wave pattern around the vessels and inside the gap. For the shorter waves, the gap influences the wave pattern both inside and outside the gap. Further, the pressure distribution on the keel surface of the vessels is asymmetric about the vertical center plane along the vessel, which resulted in roll motion eventhough the vessel is in head seas. Roll motion was observed in all gap variations considered. Amplitude modulation was observed in the heave and pitch motions, while generation of side-band frequency components were observed in the roll motion, which indicate a non-linear fluid-structure interaction.
并排配置的浮动结构常用于海洋勘探实践,如用于装载和卸载的近海船舶、浮式起重机和近海浮式风力涡轮机。计算流体动力学(CFD)方法是目前分析并排船舶水动力相互作用的常用方法。本研究的目的是对用于上述分析的 CFD 方法进行基准研究。采用 URANS CFD 方法,利用 k-ε 湍流模型和流体体积 (VOF) 方法捕捉自由表面。研究中考虑了波长与容器长度的不同比率以及容器之间的不同间隙。模拟结果表明,波长与容器长度之比 /L 对容器周围和间隙内的波型影响很大。对于较短的波,间隙对间隙内外的波型都有影响。此外,船舶龙骨表面的压力分布与沿船舶的垂直中心平面不对称,这导致即使船舶处于迎面海面也会发生翻滚运动。在考虑的所有间隙变化中都观察到了翻滚运动。在起伏和俯仰运动中观察到振幅调制,而在滚动运动中观察到边带频率成分的产生,这表明存在非线性流体-结构相互作用。
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引用次数: 0
Effects of Activation Energy and Diffusion Thermo an Unsteady MHD Maxwell Fluid Flow over a Porous Vertical Stretched Sheet in the Presence of Thermophoresis and Brownian Motion 活化能和扩散热对存在热泳和布朗运动的多孔垂直拉伸片上的非稳态 MHD 麦克斯韦流体流动的影响
Q2 Mathematics Pub Date : 2024-07-21 DOI: 10.37934/cfdl.16.12.1837
Aruna Ganjikunta, Bhagya Lakshmi Kuntumalla, Ramachandra Reddy Vaddemani
This article discusses the effects of Activation energy and Diffusion thermo on an unsteady MHD flow of an electrically conducting Maxwell Nanofluid over a stretching sheet in a porous medium in the presence of thermophoresis and Brownian motion. Using the similarity transformations, the partial differential equations corresponding to the momentum, energy, and concentration equations are transformed into a system of nonlinear ordinary differential equations, which are solved numerically using a RungeKutta fourth-order method along with the shooting technique, and the results obtained for different governing flow parameters are drawn graphically, and their effects on velocity, temperature, and concentration profiles are discussed. The values of the skin friction coefficient, Nusselt number coefficient, and Sherwood number coefficient are presented in the table. A comparison with previously reported data is made, and an excellent agreement is noted. The objective of the present study is to use the Activation energy and Diffusion thermo parameters to increase the concentration of chemical species on the boundary layer and temperature, respectively. The temperature of the fluid increases as the radiation parameter, Brownian motion, thermophoresis, and magnetic parameters increase.
本文讨论了在存在热泳和布朗运动的情况下,活化能和扩散热对多孔介质中拉伸片上导电麦克斯韦纳米流体的非稳态 MHD 流动的影响。利用相似变换,将与动量、能量和浓度方程相对应的偏微分方程转换为非线性常微分方程系统,并使用 RungeKutta 四阶方法和射影技术对其进行数值求解,以图形方式绘制了不同流动参数下的结果,并讨论了它们对速度、温度和浓度剖面的影响。表中列出了表皮摩擦系数、努塞尔特数系数和舍伍德数系数的值。与之前报告的数据进行了比较,结果表明两者非常吻合。本研究的目的是利用活化能和扩散热参数分别提高边界层上化学物种的浓度和温度。随着辐射参数、布朗运动、热泳和磁参数的增加,流体的温度也随之升高。
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引用次数: 0
MHD Stagnation Point Flow of Micropolar Fluid over a Stretching/ Shrinking Sheet 微极性流体在拉伸/收缩片上的 MHD 停滞点流动
Q2 Mathematics Pub Date : 2024-07-21 DOI: 10.37934/cfdl.16.12.113127
Dachapally Swapna, Gurala Thirupathi, Kamatam Govardhan, Ganji Narender, Santoshi Misra, S. Renuka
In this article, the stagnation point flow of a micropolar fluid on a stretching/shrinking sheet has been discussed subject to the assumption of velocity slip. Similarity transformation is used to transform the modelled Partial Differential Equations (PDEs) into a system of Ordinary Differential Equations (ODEs). The numerical results have been found by the shooting technique along with Adams Moulton method of order four. The obtained numerical results are compared with the help of Fortran Language program and compared with the earlier published results and excellent validation of the present numerical results has been achieved for the local Nusselt number. Finally, the numerical results are presented with discussion of the effects of different physical parameters.
本文在速度滑移假设的前提下,讨论了微极性流体在拉伸/收缩片上的停滞点流动。利用相似变换将模拟的偏微分方程 (PDE) 转换为常微分方程 (ODE) 系统。数值结果是通过射击技术和四阶 Adams Moulton 方法得出的。在 Fortran 语言程序的帮助下,对获得的数值结果进行了比较,并与之前公布的结果进行了比较。最后,对数值结果进行了介绍,并讨论了不同物理参数的影响。
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引用次数: 0
Unsteady MHD Walter’s-B Viscoelastic Flow Past a Vertical Porous Plate 流经垂直多孔板的非稳态 MHD 沃尔特斯-B 粘弹流
Q2 Mathematics Pub Date : 2024-07-21 DOI: 10.37934/cfdl.16.12.8596
Veera Reddy Karnati, Sandhaya Akuri, O.Ramakrishna, M. Gayatri, Srinivasa Rao Tagallamudi, Venkata Ramana Reddy Gurrampati
The present paper intended to analyse an unsteady MHD Walter’s-B viscoelastic flow past a vertical porous plate embedded in a porous medium in the presence of the radiation and chemical reaction effects. The dimensionless partial differential equations of governing equations of the flow field are solved numerically using closed analytical method. The velocity, temperature and concentration profiles are discussed graphically and discussed qualitatively
本文旨在分析在存在辐射和化学反应效应的情况下,流经嵌入多孔介质中的垂直多孔板的非稳态 MHD 沃尔特斯-B 粘弹流。流场的无量纲偏微分方程的支配方程采用闭合解析法进行数值求解。对速度、温度和浓度剖面进行了图解和定性讨论
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引用次数: 0
Effect of Inlet Pressure on the Polyurethane Spray Nozzle for Soil Cracking Improvement: Simulations using CFD Method 入口压力对用于改善土壤裂缝的聚氨酯喷嘴的影响:使用 CFD 方法进行模拟
Q2 Mathematics Pub Date : 2024-07-21 DOI: 10.37934/cfdl.16.12.5971
Tasnim Zakepeli, Nik Normunira Mat Hassan, Nur Afzanizam Samiran, Anika Zafiah Mohd Rus, Noraini Marsi, Tuan Noor Hasanah Tuan Ismail, Mohd Ridzuan Mohd Jamir, Siti Nur Azila Khalid, Muhamad Iqbal Aiman Mohd Azman
Rigid spray polyurethane (RSPU) was commercially used as an injection in crack walls or soil surfaces to enhance material performance, increase lifetime, and save operating costs. The limitation of the RSPU nozzle was reported as easily clogging when sprayed out to the insulation and crack surface area and the finished product was less aesthetically pleasing. In this study, the RSPU nozzle of flat fan nozzle, 180° angle (Design A), Hollow cone nozzle, 60° angle (Design B), and Full cone nozzle, 90° angle (Design C) were prepared by using the SOLIDWORKS software. The effect of different pressures for RSPU nozzle design at the ranges of 4Mpa, 5MPa, and 6MPa was examined by ANSYS FLUENT software. The velocity of the outer spray nozzle shows a significant increase with increasing inlet pressure of the RSPU nozzle. The results reveal that the highest velocity of RSPU was obtained at the Hollow cone nozzle (Design B) as compared to (Flat fan nozzle) Design A and (Full cone nozzle) Design C at 394.249 m/s at 4MPa, 442.327 m/s at 5MPa and 485.37 m/s at 6MPa, respectively. The distribution droplet area shows the Design B spray formation had wider area coverage at 60° and exhibited that the injection nozzle spray was scatted and uniform at 6MPa. RSPU shows the velocity increased, distribution droplet increased, and output volume spray was decreased at the increasing of injection pressure. Hence, in this study was suggested that the size of RSPU nozzle design must be made at the ranges of 60° to 90° of outlet nozzle to obtain a good RSPU area. In conclusion, design B is the most effective for RSPU nozzle and is useful in injection cracking and insulation materials applications.
硬质喷涂聚氨酯(RSPU)在商业上被用作裂缝墙或土壤表面的喷射材料,以提高材料性能、延长使用寿命并节省运营成本。据报道,RSPU 喷嘴在喷射到隔热层和裂缝表面区域时容易堵塞,而且成品不太美观。本研究使用 SOLIDWORKS 软件制备了 180° 角的扁平扇形喷嘴(设计 A)、60° 角的空心锥形喷嘴(设计 B)和 90° 角的全锥形喷嘴(设计 C)。ANSYS FLUENT 软件研究了 4MPa、5MPa 和 6MPa 范围内不同压力对 RSPU 喷嘴设计的影响。外喷嘴的速度随着 RSPU 喷嘴入口压力的增加而显著增加。结果显示,与设计 A(平扇形喷嘴)和设计 C(全锥形喷嘴)相比,空心锥形喷嘴(设计 B)获得的 RSPU 速度最高,分别为 4MPa 时 394.249 m/s、5MPa 时 442.327 m/s 和 6MPa 时 485.37 m/s。液滴面积分布显示,在 60° 时,设计 B 形成的喷雾覆盖面积更大,在 6MPa 时,喷射喷嘴的喷雾呈散射状且均匀。RSPU 表明,随着喷射压力的增加,速度增加,分布液滴增加,输出喷雾量减少。因此,本研究建议 RSPU 喷嘴的设计尺寸必须在喷嘴出口 60° 至 90° 的范围内,以获得良好的 RSPU 面积。总之,设计 B 是最有效的 RSPU 喷嘴,可用于注塑开裂和绝缘材料应用。
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引用次数: 0
Heat and Mass Transfer Effects on MHD Mixed Convective Flow of a Vertical Porous Surface in the Presence of Ohmic Heating and Viscous Dissipation 存在欧姆加热和粘性耗散时垂直多孔表面 MHD 混合对流的传热和传质效应
Q2 Mathematics Pub Date : 2024-07-21 DOI: 10.37934/cfdl.16.12.7284
Hari Krishna Yaragani, Anupama Anumolu, Vijaya Lakshmi G, Bindu Pathuri, Reddy G.V.R.
The present paper addresses the combined effects of thermal radiation and chemical reaction on steady MHD mixed convective flow of heat and mass transfer past a vertical surface under the influence of Joule and viscous dissipation. The governing system of the partial differential equations is transformed into the dimensionless equations using dimensionless variables. The dimensionless equations are solved numerically using two term perturbation technique and numerical solution as in graphically. The effects of the various parameters entering the problem on the dimensionless velocity, temperature and concentration fields within the boundary layer are discussed qualitatively. The velocity increases with an increase in Grashof number Gr, permeability parameter and solutal Grashof number Gm but decreases in magnetic parameter.
本文探讨了在焦耳耗散和粘性耗散的影响下,热辐射和化学反应对流经垂直表面的稳定 MHD 混合对流传热和传质的综合影响。利用无量纲变量将偏微分方程的支配系统转化为无量纲方程。利用两期扰动技术对无量纲方程进行数值求解,数值求解结果如图所示。定性讨论了进入问题的各种参数对边界层内无量纲速度场、温度场和浓度场的影响。速度随格拉肖夫数 Gr、渗透参数和溶质格拉肖夫数 Gm 的增加而增加,但随磁性参数的增加而减小。
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引用次数: 0
Li-NMC Temperature Modelling Based on Realistic Internal Resistance 基于真实内阻的锂-NMC 温度建模
Q2 Mathematics Pub Date : 2024-07-21 DOI: 10.37934/cfdl.16.12.140148
Muhammad Fikri Irsyad Mat Razi, Zul Hilmi Che Daud, Zainab Asus, Izhari Izmi Mazali, Anuar Abu Bakar, Mohd Kameil Abdul Hamid
Lithium-ion battery (LIB) produce heat when it is put under charging and discharging process. The heat generated during charging and discharging are directly related to the internal in the battery. This heat generation will cause the battery temperature to rise. The operating temperature for LIB is significantly important because its affect the performance and health of the battery. Gathering battery thermal behavior through experiment is a time consuming, high cost and a fussy process. The process can be made easier through battery thermal modelling. The purpose of this study is to provide a thermal battery model that can predict the battery thermal behavior at wide range of temperature by using realistic internal resistance value from experiment. In this study, a Nickel-Manganese-Cobalt Lithium-ion battery with capacity 40 Ah was discharged with 120 A (3C) and 160 A (4C) current continuously to heat up the battery until a set of targeted temperature achieved. The battery is then discharged with 40 A (1C) pulse current, and the voltage response is measured. The process was repeated until 80°C. From the voltage response data, the internal resistance for the battery was calculated and used as the main input in the thermal model based on heat generation equation to predict the battery temperature. The result shows that the developed thermal model managed to precisely predict battery thermal behaviour with a low average relative error of around 0.634 % to 5.244%. The significance of this study is to provide a battery model that can predict battery thermal behavior precisely at wide range of temperature. This information is important in designing a better battery management system (BMS) to prolong the battery lifetime, slowing degradation rate and avoid safety risk.
锂离子电池(LIB)在充放电过程中会产生热量。充放电过程中产生的热量与电池内部直接相关。这些热量会导致电池温度升高。锂电池的工作温度非常重要,因为它会影响电池的性能和健康。通过实验收集电池的热行为是一个耗时、高成本且繁琐的过程。而通过电池热建模可以简化这一过程。本研究的目的是提供一种电池热模型,通过使用实验得出的实际内阻值,预测电池在宽温度范围内的热行为。在这项研究中,以 120 A(3C)和 160 A(4C)电流连续放电,加热容量为 40 Ah 的镍-锰-钴锂离子电池,直到达到设定的目标温度。然后以 40 A(1C)脉冲电流对电池放电,并测量电压响应。该过程重复进行,直至 80°C。根据电压响应数据计算出电池内阻,并将其作为基于发热方程的热模型的主要输入,以预测电池温度。结果表明,所开发的热模型能够精确预测电池的热行为,平均相对误差较小,约为 0.634 % 至 5.244%。这项研究的意义在于提供了一种电池模型,可以精确预测电池在宽温度范围内的热行为。这些信息对于设计更好的电池管理系统 (BMS) 以延长电池寿命、减缓电池退化率和避免安全风险非常重要。
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引用次数: 0
Numerical Investigation of Thermal Performance for Turbulent Water Flow through Dimpled Pipe 湍流水流过凹陷管道的热性能数值研究
Q2 Mathematics Pub Date : 2024-07-21 DOI: 10.37934/cfdl.16.12.97112
Ansam Adil Mohammed, Mahmoud Sh. Mahmoud, Suha K Jebir, Ahmed F. Khudheyer
Dimples are tiny indentations on the surfaces of the body that enhance heat transfer and alter fluid flow characteristics on or within the body. Numerical investigations were conducted to analyse the heat transfer and flow characteristics in a cross-combined dimple tube in the range of Reynolds numbers from 6000 to 14000. The finite volume method recognised a novel enhancement model utilising methods for composite-form surfaces. Compared to a smooth tube working similarly, the effects significantly improve the heat transfer index, performance evaluation criteria, and friction factor. A three-dimensional simulation was conducted to clarify the underlying process by which dimples affect thermal performance. The simulation findings suggest that the dimples effectively enhance heat transfer by altering the temperature distribution and increasing the temperature gradient within the central area of the dimple section. A concave surface profile disrupts the flow and prevents the formation of a stable boundary layer, promoting the mixing of hot and cold fluids. Furthermore, the study investigates how geometric characteristics impact thermal and hydraulic efficiencies, emphasising that larger dimples improve overall thermo-hydraulic performance. Specifically, the heat transfer enhancement achieved an average increase of 17.3%, ranging from 18.03% to 38.6%, surpassing that of the traditional smooth tube.
凹痕是管体表面的微小凹痕,可增强热传递并改变管体上或管体内的流体流动特性。我们进行了数值研究,分析了雷诺数在 6000 到 14000 之间的交叉组合凹陷管中的传热和流动特性。有限体积法利用复合形式表面的方法识别了一个新的增强模型。与工作方式类似的光滑管相比,其效果明显改善了传热指数、性能评估标准和摩擦系数。我们进行了三维模拟,以阐明凹点影响热性能的基本过程。模拟结果表明,凹痕通过改变温度分布和增加凹痕部分中心区域的温度梯度,有效地提高了传热效果。凹面轮廓会扰乱流动,阻止形成稳定的边界层,促进冷热流体的混合。此外,该研究还探讨了几何特征如何影响热效率和液压效率,并强调较大的凹陷可改善整体热液压性能。具体而言,传热性能平均提高了 17.3%,从 18.03% 到 38.6% 不等,超过了传统的光滑管。
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引用次数: 0
Effect of Different Shapes of Nanoparticles on Mixed Convective Nanofluid Flow in a Darcy-Forchhiemer Porous Medium 不同形状的纳米颗粒对达西-福尔希默多孔介质中混合对流纳米流体流动的影响
Q2 Mathematics Pub Date : 2024-07-21 DOI: 10.37934/cfdl.16.12.3858
Annapurna T, K.S.R. Sridhar, M Karuna Prasad
The nanofluid has diverse applications in industries, engineering, and medicine due to its greater thermal characteristics. However, various factors such as the shape and size of nanoparticles, the base fluid, the porous medium, the quadratic drag force, and the viscous dissipation have significant effects on the flow and heat transfer characteristics of nanofluids. Therefore, it is crucial to study the influence of these factors. In this paper, a theoretical investigation is conducted to analyze the mechanisms of thermal conductivities of different shapes of nanoparticles, such as platelet, cylinder, brick and blade on the mixed convective nanofluid flow in a vertical channel saturated with porous medium. Consider ethylene glycol and water as base fluids for the nanoparticles, including copper, aluminum oxide, titanium oxide, silver, and iron oxide. A thin, movable baffle plate of negligible thickness is inserted in the channel and made into double passages. To define the porous matrix, the Darcy-Brinkaman-Forchhiemer model is used, and to define the nanofluid, the Tiwari and Das model is used. Robin boundary conditions are considered for the channel flow. The differential transform method (DTM) is applied to solve non-linear governing equations with inertia, and the perturbation method is applied to solve the problem without inertia. Velocity and temperature cantors are shown graphically using MATLAB and MATHEMATICA. The obtained values by DTM and the perturbation method are well validated and shown graphically. The Nusselt number was evaluated and tabulated for all governing parameters. The objective of this article is to investigate the effect of nonspherical shapes of nanoparticles, the base fluid, the inertial forces of the porous medium, and the buoyancy force on the thermal characteristics of flow and heat transfer of nanofluids. The main findings of this problem are that the optimum velocity and temperature cantor are found for platelet-shaped water-based silver nanofluid.
纳米流体具有更强的热特性,因此在工业、工程和医学领域有着广泛的应用。然而,纳米颗粒的形状和尺寸、基流体、多孔介质、二次阻力和粘性耗散等各种因素对纳米流体的流动和传热特性有显著影响。因此,研究这些因素的影响至关重要。本文通过理论研究,分析了不同形状的纳米颗粒(如板状、圆柱状、砖状和叶片状)对多孔介质饱和垂直通道中混合对流纳米流体流动的导热机理。考虑将乙二醇和水作为纳米粒子(包括铜、氧化铝、氧化钛、银和氧化铁)的基流体。在通道中插入厚度可忽略不计的活动薄挡板,使其成为双通道。多孔基质的定义采用达西-布林卡曼-福尔希默模型,纳米流体的定义采用蒂瓦里和达斯模型。通道流考虑了罗宾边界条件。微分变换法(DTM)用于求解有惯性的非线性控制方程,扰动法用于求解无惯性的问题。速度和温度曲线用 MATLAB 和 MATHEMATICA 图形显示。通过 DTM 和扰动法获得的数值得到了很好的验证,并以图形显示。对所有控制参数的努塞尔特数进行了评估并制成表格。本文旨在研究非球形纳米颗粒、基流体、多孔介质惯性力和浮力对纳米流体流动和传热热特性的影响。该问题的主要发现是找到了板状水基银纳米流体的最佳速度和温度坎托。
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引用次数: 0
Numerical Analysis and Design for Thermal Efficiency Optimization using Al2O3 Nanofluids in Shell and Tube Heat Exchangers 使用 Al2O3 纳米流体优化管壳式热交换器热效率的数值分析与设计
Q2 Mathematics Pub Date : 2024-07-05 DOI: 10.37934/cfdl.16.11.146160
Mohammed Abbood, Yaser Alaiwi, Ahmad Jundi
In this study, the efficacy of aluminum oxide (Al2O3) nanofluids at a 2% concentration for enhancing heat transfer in shell and tube heat exchangers is evaluated. By employing SOLIDWORKS for the innovative design and Computational Fluid Dynamics (CFD) for simulation, an improvement in heat transfer efficiency over traditional hot water systems is identified. Emphasizing the unique properties of Al2O3 nanofluids in augmenting heat transfer rates, the role of advanced CAD and simulation tools in engineering practices is highlighted. Results confirm nanofluids' benefits in improving thermal management systems, indicating their potential to decrease energy consumption and operational costs. Furthermore, the exploration of a novel design for heat exchangers, inspired by but distinct from existing market standards, suggests new avenues for the application of nanofluids in various industrial settings, marking a step towards more energy-efficient technologies.
本研究评估了浓度为 2% 的氧化铝 (Al2O3) 纳米流体在管壳式热交换器中增强传热的功效。通过采用 SOLIDWORKS 进行创新设计和计算流体动力学(CFD)进行模拟,发现与传统热水系统相比,纳米流体的传热效率有所提高。通过强调 Al2O3 纳米流体在提高传热率方面的独特性能,突出了先进 CAD 和模拟工具在工程实践中的作用。研究结果证实了纳米流体在改善热管理系统方面的优势,表明其具有降低能耗和运营成本的潜力。此外,受现有市场标准的启发但又与之不同的新型热交换器设计的探索,为纳米流体在各种工业环境中的应用提出了新的途径,标志着向更节能的技术迈进了一步。
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引用次数: 0
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