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NUMERICAL INVESTIGATION OF THE NANOFLUID NATURAL CONVECTION FLOW IN A CPU HEAT SINK USING BUONGIORNO TOW-PHASE MODEL 利用BUONGIORNO拖曳相模型对CPU散热器中纳米流体自然对流的数值研究
IF 0.4 Q4 ENGINEERING, MULTIDISCIPLINARY Pub Date : 2022-12-01 DOI: 10.24874/jsscm.2022.16.02.02
Yamina Anouar, Abderrahim Mokhefi
In this paper, a numerical investigation using the finite element method on the cooling capacity of an electronic heat sink has been presented. This heat sink is intended for cooling applications of micro-computer CPUs. It deals with a parallelepipedal block with rectangular fins, filled with a nanofluid and crossed by four cylindrical pipes in which a cooling gas flows and dissipates the heat generated by the processor. Indeed, the cooling occurs by three transfers: the first one evacuates the heat from the processor towards the gas, the second one transfers this heat towards the nanofluid and the last one is cooled from the ambient air by means of the fins laterally arranged on the block. From this work, it has been planned to contribute to the study of the behavior of a nanofluid in the heat sink in the presence of a uniform magnetic field in order to enhance the operating and cooling performances. The effects of some control parameters have been highlighted on the hydrodynamic, thermal, and mass behavior of the nanofluid, namely: the Rayleigh number (103 ≤ Ra ≤ 105), the Hartmann number (0 ≤ Ha ≤ 100), the angle of inclination of the magnetic field (0 ≤ γ ≤ 90°) and the nanoparticles diameter (1 nm ≤ dp ≤ 10 nm). On the other hand, a new fin design has been proposed in this study allowing the enhancement of the heat exchange rate with ambient medium. The studied phenomenon is governed by the equations of the two-phase nanofluid model proposed by Buongiorno and which describe the following balances: mass, momentum, energy and nanoparticles. The system of partial differential equations with initial-boundary conditions has been solved by the finite element method. After performing a mesh independence check and validating with previous papers, the results of the investigation were presented. They showed that the application of a magnetic field significantly reduces the rate of heat exchange. However, increasing the angle of inclination of this field promotes convective heat transfer. Moreover, the use of zigzag fins improves the cooling rate by about 4% for amplitude of 0.05 compared to the standard configuration.
本文采用有限元方法对电子散热器的冷却能力进行了数值研究。该散热器适用于微型计算机CPU的冷却应用。它处理的是一个带有矩形翅片的平行六面体块,填充有纳米流体,由四根圆柱形管道穿过,冷却气体在其中流动并消散处理器产生的热量。事实上,冷却通过三种方式进行:第一种将热量从处理器排出到气体中,第二种将热量转移到纳米流体中,最后一种通过横向布置在块上的散热片从环境空气中冷却。这项工作计划有助于研究在均匀磁场存在下散热器中纳米流体的行为,以提高操作和冷却性能。一些控制参数对纳米流体的流体动力学、热学和质量行为的影响已经得到强调,即:瑞利数(103‰Ra‰105)、哈特曼数(0‰Ha‰100)、磁场倾角(0‰Isla³90°)和纳米颗粒直径(1 nm‰dp‰10 nm)。另一方面,本研究提出了一种新的翅片设计,可以提高与环境介质的热交换率。所研究的现象由Buongiorno提出的两相纳米流体模型方程控制,该方程描述了以下平衡:质量、动量、能量和纳米颗粒。用有限元方法求解了具有初始边界条件的偏微分方程组。在进行了网格独立性检查并与以前的论文进行了验证后,给出了研究结果。他们表明,磁场的应用显著降低了热交换的速率。然而,增加该场的倾角会促进对流传热。此外,与标准配置相比,锯齿形翅片的使用将振幅为0.05的冷却率提高了约4%。
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引用次数: 0
COST-EFFECTIVENESS ANALYSIS OF IN SILICO CLINICAL TRIALS OF VASCULAR STENTS 血管支架计算机辅助临床试验的成本效益分析
IF 0.4 Q4 ENGINEERING, MULTIDISCIPLINARY Pub Date : 2022-12-01 DOI: 10.24874/jsscm.2022.16.02.08
Milica Kaplarević, Marija Gačić, G. Karanasiou, D. Fotiadis, Nenad Filipović
Today, it takes ten to twelve years on average to complete a clinical trial before a new drug is approved and brought to marktet. Moreover, the evaluation of the efficacy and safety of drugs or devices has been performed in the linear and sequential manner with limited change over the past decade. The InSilc project is an EU funded project (www.insilc.eu) within which the InSilc platform was developed for designing, developing and assessing coronary stents. The InSilc platform contains the following modules: Mechanical Modelling Module, 3D Reconstruction and Plaque Characterization Tool, Deployment Module, Fluid Dynamics Module, Drug Delivery Module, Degradation Module, Myocardial Perfusion Module, Virtual Population Physiology and Virtual Population Database. We analyze the cost of three different in silico scenarios for clinical study. In Scenario 1, two different stent designs are compared according to the ISO standard for in silico mechanical tests. Scenario 2 predicts the stenting outcome for a virtual anatomy where design/material could be changed. Scenario 3 compares two stents using the same virtual anatomies from the Virtual vessel database. Cost-effectiveness analysis was performed for real clinical trials with metallic and BVS stent and in silico clinical trials. It was observed that in silico clinical trials are almost 90 times cheaper than real clinical trials for 1000 patients. In Silico clinical trials will not completely replace real clinical studies but the evidence shows that they can significantly reduce the cost of a real clinical study which will open a new avenue for future hybrid real and in silico clinical trials.
如今,一种新药在获得批准并投入市场之前,平均需要十到十二年的时间才能完成一项临床试验。此外,在过去十年中,药物或装置的疗效和安全性评估一直以线性和顺序的方式进行,变化有限。InSilc项目是一个欧盟资助的项目(www.InSilc.EU),在该项目中,InSilc平台被开发用于设计、开发和评估冠状动脉支架。InSilc平台包含以下模块:机械建模模块、三维重建和斑块表征工具、部署模块、流体动力学模块、给药模块、降解模块、心肌灌注模块、虚拟群体生理学和虚拟群体数据库。我们分析了三种不同的临床研究方案的成本。在场景1中,根据ISO标准对两种不同的支架设计进行比较,以进行硅内机械测试。场景2预测了设计/材料可能发生变化的虚拟解剖结构的支架植入结果。场景3比较了使用虚拟血管数据库中相同虚拟解剖结构的两个支架。对金属支架和BVS支架的实际临床试验以及计算机临床试验进行了成本效益分析。据观察,针对1000名患者的计算机临床试验几乎比实际临床试验便宜90倍。在Silico,临床试验不会完全取代真正的临床研究,但有证据表明,它们可以显著降低真正临床研究的成本,这将为未来的混合真实和计算机临床试验开辟一条新的途径。
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引用次数: 0
FINITE ELEMENT ANALYSIS OF A KNEE JOINT DURING JUMP 膝关节在跳跃过程中的有限元分析
IF 0.4 Q4 ENGINEERING, MULTIDISCIPLINARY Pub Date : 2022-12-01 DOI: 10.24874/jsscm.2022.16.02.06
Radivoje Radaković, Aleksandra Vulović, T. Exarchos, Nenad Filipović
Athletes experience high levels of stress during sports activities. One of the most common activities is jumping. This is a very complex activity, which can lead to injuries and long recovery periods. In this research, professional athletes performed jumps in order to obtain ground force values from a force plate. A combination of ground force measurement and inverse dynamics was used to obtain knee joint force values during jumping. The obtained values were then used for the finite element analysis of a knee joint model in order to calculate stress values in the knee joint, with focus on femoral cartilage and menisci. The highest stress values were obtained at the anterior and posterior horn of the medial meniscus, with the highest stress value of 4.894 MPa. Femoral cartilage had lower value, with the maximum stress of 0.391 MPa.
运动员在体育活动中会承受很大的压力。最常见的活动之一是跳跃。这是一项非常复杂的活动,可能会导致受伤和长时间的恢复。在这项研究中,职业运动员进行跳跃,以从力板中获得地面力值。地面力测量和反向动力学相结合用于获得跳跃过程中的膝关节力值。然后将获得的值用于膝关节模型的有限元分析,以计算膝关节中的应力值,重点是股软骨和半月板。在内侧半月板的前角和后角获得了最高的应力值,最高应力值为4.894MPa。股骨软骨的应力值较低,最大应力为0.391MPa。
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引用次数: 0
FREE TRANSVERSE VIBRATIONS OF CANTILEVER BEAM FOR TAPERED THICKNESS PREPARED FROM VARIANT FIBERS REINFORCED POLYESTER 由不同纤维增强聚酯制成的锥形厚度悬臂梁的自由横向振动
IF 0.4 Q4 ENGINEERING, MULTIDISCIPLINARY Pub Date : 2022-12-01 DOI: 10.24874/jsscm.2022.16.02.01
Nawal H. Al-Raheimy, Lekaa Hammed
The natural frequency of the cantilever beam for the tapered thickness in the current paper is estimated using a Raleigh-Ritz approach. The study explores the effect of different parameters on the behavior of the beam such as the length of beam “L”, thickness at clamped end “hc”, width “b”, the ratio of thickness at free end to thickness at clamped end “hf/hc”, types of fibers and the concentration of fibers “f” in the resin of unsaturated polyester representing the matrix. The resin can be reinforced by aligned long fibers such as E-fibers glass, Kevlar-49 and carbon fibers. When a tapered beam is formed from a composite material, the natural frequency decreases when the length of the beam and the ratio of the thickness “hf/hc” increase; however, the frequency increases as the width of the beam increases. The thickness at the clamped end likewise increases as the volume fraction of fibers in the resin increases. The carbon fiber beam has a higher natural frequency than the other types of fibers. Finally, the results were compared to other available results and were determined to be consistent.
本文采用Raleigh-Riz方法估算了锥形厚度悬臂梁的固有频率。该研究探讨了不同参数对梁性能的影响,如梁的长度“L”、夹持端的厚度“hc”、宽度“b”、自由端厚度与夹持端厚度之比“hf/hc”,纤维的类型以及代表基质的不饱和聚酯树脂中纤维的浓度。树脂可以通过排列的长纤维增强,例如E-纤维玻璃、Kevlar-49和碳纤维。当锥形梁由复合材料形成时,当梁的长度和厚度比“hf/hc”增加时,固有频率降低;然而,频率随着光束宽度的增加而增加。夹持端的厚度同样随着树脂中纤维体积分数的增加而增加。碳纤维梁具有比其他类型的纤维更高的固有频率。最后,将结果与其他可用结果进行比较,确定结果一致。
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引用次数: 0
THE EFFECT OF ROTATION RATES, CYLINDER DIAMETER AND LATERAL BOUNDARIES ON STROUHAL NUMBER IN UNSTEADY REGIMES AT DIFFERENT REYNOLDS NUMBERS 不同雷诺数非定常条件下,转速、柱体直径和侧向边界对涡流哈尔数的影响
IF 0.4 Q4 ENGINEERING, MULTIDISCIPLINARY Pub Date : 2022-12-01 DOI: 10.24874/jsscm.2022.16.02.04
M. Essahraoui, R. El Bouayadi, A. Saad
The lateral boundary conditions, rotation rates parameters, domain size, cylinder diameter, and Reynolds number are all responsible for the variation of the Strouhal number. In this study, we have varied the domain size, lateral boundary conditions, downstream locations, and the cylinder diameter at specific values of Reynolds number for stationary and rotating cylinders in order to spot the difference in each case. The effect of the rotating cylinder on the flow behavior downstream leads to a variation of Strouhal number. Thus, we have rotated the circular cylinder clockwise and counter-clockwise in order to visualize its effect on the Strouhal number values. An unsteady study was developed for laminar and turbulent regimes from 𝑅𝑒=60 to 𝑅𝑒=3900.
横向边界条件、旋转速率参数、畴尺寸、圆柱体直径和雷诺数都是影响Strouhal数变化的因素。在本研究中,我们改变了固定和旋转圆柱体在特定雷诺数值下的区域大小、横向边界条件、下游位置和圆柱体直径,以发现每种情况下的差异。旋转筒体对下游流动特性的影响导致了斯特劳哈尔数的变化。因此,我们顺时针和逆时针旋转圆柱体,以便可视化其对斯特罗哈尔数值的影响。对从ð ' '…ð ' ' " =60到ð '…ð ' ' " =3900的层流和湍流状态进行了非定常研究。
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引用次数: 0
RENORMALIZATION GROUP METHOD FOR A CLASS OF LAGRANGE MECHANICAL SYSTEMS 一类拉格朗日机械系统的重整化群方法
IF 0.4 Q4 ENGINEERING, MULTIDISCIPLINARY Pub Date : 2022-12-01 DOI: 10.24874/jsscm.2022.16.02.07
Zheng Mingliang
Considering the important role of small parameter perturbation term in mechanical systems, the perturbed dynamic differential equations of Lagrange systems are established. The basic idea and method of solving ordinary differential equations by normal renormalization group method are transplanted into a kind of Lagrange mechanical systems, the renormalization group equations of Euler-Lagrange equations are obtained, and the first-order uniformly valid asymptotic approximate solution of Lagrange systems with a single-degree-of-freedom is given. Two examples are used to show the calculation steps of renormalization group method in detail as well as to verify the correctness of the method. The innovative finding of this paper is that for integrable Lagrange systems, its renormalization group equations are also integrable and satisfy the Hamilton system's structure.
考虑到小参数摄动项在机械系统中的重要作用,建立了拉格朗日系统的摄动动力微分方程。将正规重整化群法求解常微分方程的基本思想和方法移植到一类拉格朗日力学系统中,得到了欧拉-拉格朗日方程的重整化群方程,给出了单自由度拉格朗日系统的一阶一致有效渐近近似解。通过两个算例详细说明了重整化群方法的计算步骤,并验证了该方法的正确性。本文的创新发现是,对于可积的拉格朗日系统,其重整化群方程也是可积的,并且满足Hamilton系统的结构。
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引用次数: 0
UNSTEADY NUMERICAL INVESTIGATION OF FERROFLUID FORCED CONVECTION OVER A DOWNWARD STEP CONTAINING A ROTATING FINNED CYLINDER 含旋转翅片圆柱下台阶铁磁流体强迫对流的非定常数值研究
IF 0.4 Q4 ENGINEERING, MULTIDISCIPLINARY Pub Date : 2022-12-01 DOI: 10.24874/jsscm.2022.16.02.05
Meriem Toumi, M. Bouzit, Abderrahim Mokhefi, Djamila Derbal
The unsteady investigation of ferrofluid flow forced convection over a downward step containing a rotating finned cylinder is conducted numerically. The dimensionless partial differential equations of conservation equations for mass, momentum and energy and the boundary conditions associated with them are solved by using the finite element method. Two control parameters are used, the angular velocity Ω (-5, -3, -1, 0, 1, 3, 5) and the Reynolds number Re (10, 20, 50, 100), and their effect as a function of time on flow characteristics and heat transfer is presented. To understand how the rotation of the finned cylinder and Reynolds number affects the heat transfer and fluid flow characteristics, an analysis is made and the results obtained are presented qualitatively by the streamlines and the isotherms and quantitatively by calculating the average and local Nusselt number. It has been observed that the rotation of the finned cylinder enhanced heat transfer significantly. A difference of 177.33% improvement is observed between a rotational speed of a finned cylinder (Ω = -5) in the present paper and that of a cylinder without fin (Ω = 25) in the reference paper.
用数值方法研究了含旋转翅片圆柱的下台阶上铁磁流体流动的强迫对流。用有限元方法求解了质量、动量和能量守恒方程的无量纲偏微分方程及其相关的边界条件。使用了两个控制参数,角速度Isla(-5,-3,-1,0,1,3,5)和雷诺数Re(10,20,50100),并给出了它们作为时间函数对流动特性和传热的影响。为了了解翅片圆柱的旋转和雷诺数如何影响传热和流体流动特性,进行了分析,并通过流线和等温线定性地给出了获得的结果,通过计算平均值和局部努塞尔数定量地给出了结果。已经观察到,翅片圆柱的旋转显著地增强了传热。在本文中观察到带翅片的圆柱体(Isla©=-5)的转速与参考文献中不带翅片的圆柱形(Isla©=25)的转速之间的差异为177.33%。
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引用次数: 0
NUMERICAL INVESTIGATION OF SUPERSONIC FLOW SEPARATION IN THRUST-OPTIMIZED CONTOUR ROCKET NOZZLE 推力优化外形火箭喷管内超音速流分离的数值研究
IF 0.4 Q4 ENGINEERING, MULTIDISCIPLINARY Pub Date : 2022-12-01 DOI: 10.24874/jsscm.2022.16.02.03
Bensayah Khaled, Kamri Khadidja
The difficulties associated with thrust-optimized contour nozzles have led to significant advances in our knowledge of the physical phenomena associated with flow separation. In this study, a fully implicit scheme is implemented using a combined weight function for splitting the flux to analyze the shock patterns in the optimized contour (TOC) that occur during the process of separation, leading to free (FSS) or restricted (RSS) shock separation. The switching FSS/RSS hysteresis at startup and shutdown is also investigated. To better understand and validate the findings and study the properties of the oscillating flow during the start-up procedure, an axisymmetric two-dimensional numerical simulation was performed for the TOC nozzle. A code was developed to solve the unsteady Navier-Stokes equations for compressible nozzle flow with boundary layer/shock wave interactions with the implementation of a full RSM-Omega turbulence model. These findings were used to analyze the separation structures, shock wave interactions, and hysteresis phenomena.
与推力优化轮廓喷嘴相关的困难导致我们对与流分离相关的物理现象的认识取得了重大进展。在本研究中,使用组合权重函数来分割通量,以分析在分离过程中发生的优化轮廓(TOC)中的冲击模式,从而导致自由(FSS)或限制(RSS)冲击分离,实现了一种完全隐式的方案。还研究了开关FSS/RSS在启动和关闭时的滞后现象。为了更好地理解和验证这些发现,并研究启动过程中振荡流的特性,对TOC喷嘴进行了轴对称二维数值模拟。开发了一个代码来求解具有边界层/冲击波相互作用的可压缩喷嘴流的非定常Navier-Stokes方程,并实现了全RSM Omega湍流模型。这些发现被用于分析分离结构、冲击波相互作用和磁滞现象。
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引用次数: 1
BUCKLING OF SHALLOW SHELLS OF DOUBLE CURVATURE STIFFENED BY RIBS FROM THE OUTSIDE 外肋加肋双曲扁壳的屈曲
IF 0.4 Q4 ENGINEERING, MULTIDISCIPLINARY Pub Date : 2022-11-01 DOI: 10.24874/jsscm.2022.16.01.05
A. Semenov
The results of a computational experiment on the analysis of the effectiveness of placing stiffeners on the outer side of the shell structure are presented. The calculations were carried out on the basis of a geometrically nonlinear mathematical model that takes into account transverse shears and orthotropy of the material. The calculation algorithm is based on the Ritz method and the method of continuing the solution with respect to the best parameter. To take into account stiffeners, the refined discrete method, proposed by the author earlier, is used. Shallow shells of double curvature are analyzed. The structures are made of steel and are simply supported, the stiffening ribs are arranged orthogonally. The values of critical buckling loads are presented. The effectiveness of the location of the stiffeners on the outer side of the shell structure is shown. It is revealed that the location of the ribs on the outside increases the value of the critical buckling load.
给出了在壳体结构外侧设置加劲肋的有效性分析的计算实验结果。计算是在考虑材料横向剪切和正交性的几何非线性数学模型的基础上进行的。计算算法基于Ritz方法和关于最佳参数的连续求解方法。为了考虑加劲肋,使用了作者早先提出的精细离散方法。对双曲扁壳进行了分析。结构由钢制成,并进行简单支撑,加劲肋正交布置。给出了临界屈曲载荷的值。显示了壳体结构外侧加劲肋位置的有效性。结果表明,肋在外侧的位置增加了临界屈曲载荷的值。
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引用次数: 0
THERMAL ANALYSIS OF LAMINAR WATER FLOW OVER A BACKWARD FACING CHANNEL WITH CARBON NANOPARTICLES 碳纳米颗粒后向通道层流水流的热分析
IF 0.4 Q4 ENGINEERING, MULTIDISCIPLINARY Pub Date : 2022-11-01 DOI: 10.24874/jsscm.2022.16.01.09
S. Saha, V. Ramachandra Prasad, Osman Anwar Bég
In the last few years, the thermo-hydraulic simulation of nanofluid flow bifurcation phenomena has become of great interest to researchers and a useful tool in many engineering applications. FVM has been employed in this article to numerically explore the laminar water flow over a backward facing channel with or without carbon nanoparticles (CN). The problem formulated in this paper has been solved by considering the effects of nanoparticle weight percentages (𝑤%), such as 0.00, 0.12, and 0.25 for different Reynolds number (𝑅𝑒). Nusselt number distribution (𝑁𝑢(𝑥)), coefficient of skin friction (𝐶𝑓), characteristics of pressure drop (Δ𝑝), velocity contours, static temperature, pumping power (𝑃𝑝) and thermal resistance factor (𝑅) have been investigated to know the behavior of thermo-hydraulic flow bifurcation phenomena. The present study shows that the surface temperature and coefficient of heat transfer can be reduced due to the effect of 𝑅𝑒 or w%. For different w%, it has been found that in the rise in the values of 𝑅𝑒 causes the increase of vortex length and as a result velocity gradient and Δ𝑝 arises. Furthermore, it has also been studied that the enhancement of 𝑅𝑒 causes the increaseof 𝑃𝑝 and Δ𝑝.
近年来,纳米流体流动分岔现象的热液模拟已成为研究人员非常感兴趣的问题,并在许多工程应用中成为一种有用的工具。本文采用FVM对有或无碳纳米颗粒(CN)的后向通道层流水流进行了数值研究。通过考虑不同雷诺数(ð ' '…ð ' ' ")下纳米颗粒质量百分比(ð ' '·%)的影响,如0.00、0.12和0.25,解决了本文提出的问题。研究了Nusselt数分布(ð ' ' ð ' '¥)、表面摩擦系数(ð ' '¶ð ' ' ' ' ')、压降特性(Î " ð ' ' ' ' ')、速度曲线、静态温度、泵送功率(ð ' ƒð ' ' ' ' ')和热阻因子(ð ' '…),以了解热液流分岔现象的行为。本研究表明,由于ð '…ð ' '或w%的影响,表面温度和传热系数可以降低。对于不同的w%,发现在ð ' '…ð ' ' "值的升高中,会引起涡流长度的增大,从而产生速度梯度和Î " ð ' ' '。此外,还研究了ð '…ð ' '”的增强导致ð ' ƒð ' '”和Γð ' '”的增加。
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引用次数: 0
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Journal of the Serbian Society for Computational Mechanics
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