Impact of radiation,melting,and chemical reaction on magnetohydrodynamics nanoparticle aggregation flow across parallel plates

The heat transfer between two corresponding plates,disks,and concentric pipes has many applications,including water cleansing and lubrication.Furthermore,TiO_(2)-water-based nanofluids are used widely because it is useful for operating and controlling the temperature,especially in photovoltaic technology and solar panels.Motivated by these applications,the current study is based on the nanoparticle aggregation effect on magnetohydrodynamics(MHD)flow via rotating parallel plates with the chemical reaction.To achieve maximum heat transportation,the Bruggeman model is used to adapt the Maxwell model.Also,melting and thermal radiation effects are considered in the modeling to discuss heat transport.The Runge-Kutta-Fehlberg 4th−5th order method is used to attain numerical solutions.The main focus of this study is to see the thermodynamic behavior considering several aspects of nanoparticle aggregation.The heat transfer rate between the parallel plates is enhanced by improving the thermophoresis,radiation,and Brownian motion parameters.The rise in Schmidt number and chemical reaction rate parameter decreases the concentration distribution.This study will be helpful in enhancing the thermal efficiency of photovoltaic technology in solar plates,water purifying,thermal management of electronic devices,designing effective cooling systems,and other sustainable technologies.

UNSTEADY FLOWS OF A GENERALIZED SECOND GRADE FLUID WITH THE FRACTIONAL DERIVATIVE MODEL BETWEEN TWO PARALLEL PLATES

The fractional calculus approach in the constitutive relationship model of a generalized second grade fluid is introduced.Exact analytical solutions are obtained for a class of unsteady flows for the generalized second grade fluid with the fractional derivative model between two parallel plates by using the Laplace transform and Fourier transform for fractional calculus.The unsteady flows are generated by the impulsive motion or periodic oscillation of one of the plates.In addition,the solutions of the shear stresses at the plates are also determined.

Study on Interaction Between Two Parallel Plates with Iteration Method in Functional Theory

By introducing the functional theory into the calculation of electric double layer （EDL） interaction, the interaction energies of two parallel plates were calculated respectively at low, moderate, and high potentials. Compared with the results of two existing methods, Debye-Hückel and Langmuir methods, which are applicable just to the critical potentials and perform poorly in the intermediate potential, the functional approach not only has much simpler expression of the EDL interaction energy, but also performs well in the entire range of potentials.

A New Idea of Fractal-Fractional Derivative with Power Law Kernel for Free Convection Heat Transfer in a Channel Flow between Two Static Upright Parallel Plates

Nowadays some new ideas of fractional derivatives have been used successfully in the present research community to study different types of mathematical models.Amongst them,the significant models of fluids and heat or mass transfer are on priority.Most recently a new idea of fractal-fractional derivative is introduced;however,it is not used for heat transfer in channel flow.In this article,we have studied this new idea of fractal fractional operators with power-law kernel for heat transfer in a fluid flow problem.More exactly,we have considered the free convection heat transfer for a Newtonian fluid.The flow is bounded between two parallel static plates.One of the plates is heated constantly.The proposed problem is modeled with a fractal fractional derivative operator with a power-law kernel and solved via the Laplace transform method to find out the exact solution.The results are graphically analyzed via MathCad-15 software to study the behavior of fractal parameters and fractional parameter.For the influence of temperature and velocity profile,it is observed that the fractional parameter raised the velocity and temperature as compared to the fractal operator.Therefore,a combined approach of fractal fractional explains the memory of the function better than fractional only.

Experiment investigation on visualization and operating characteristics of closed loop plate oscillating heat pipe with parallel channels

Using ethanol or acetone as the working fluid, visualization of oscillations in steady state was observed visually by high-speed cameras, and temperature oscillating and heat transfer characteristics of closed-loop plate oscillating heat pipe with parallel channels(POHP-PC) were experimentally investigated by varying liquid filled ratios(50%, 70%, 85%), section scales(1 mm×1 mm and 1 mm×1.5 mm), inclination angles, working fluids and heating inputs. It was found that during operating there was mixed flow consisting of plug flow and annular flow in channels of oscillating heat pipe at steady-state. There was an equilibrium position for working fluid of condenser during oscillating, and periodic oscillations occurred up and down in the vicinity of equilibrium position. With heat input increasing, equilibrium position rose slowly as a result of vapor pressure of evaporation.Evaporation temperature oscillating amplitude possessed a trend of small-large-small and frequency trend was of small-large during steady-state. It may be generally concluded that temperature, whether evaporator or condenser, fluctuated sharply or rose continuously when oscillating heat pipe coming to dry burning state. Simultaneously, it was found that temperature difference of cooling water possibly dropped with heat input rising during dry burning state. Thermal resistance of No. 2 with acetone was lower than that of No. 1 during experiments, but No. 2 achieving heat transfer limit was earlier than No. 1. However, with ethanol, thermal resistance of No. 1 and No. 2 were similar with the heating input less than 110-120 W and filling ratios of 50% and 70%. And with filling ratio of 85%, heating transfer performance of No. 2 was better compared to No. 1 during all the experiments.

OPTIMIZATION OF TRANSIENT FEEDING TO PARALLEL-PLATE TRANSMISSION LINES FROM COAXIAL LINE

The transient feeding to parallel-plate transmission lines from coaxial line is optimized by using the Finite-Difference Time-Domain (FDTD) method and a simple FDTD feed model. Observing the reflected voltages, this letter presents the optimal feeding position and ratio of width to height for a given input impedance of the coaxial line.

Mathematical Analysis of Unsteady MHD Blood Flow through Parallel Plate Channel with Heat Source

In the present study, a mathematical model of unsteady blood flow through parallel plate channel under the action of an applied constant transverse magnetic field is proposed. The model is subjected to heat source. Analytical expressions are obtained by choosing the axial velocity;temperature distribution and the normal velocity of the blood depend on y and t only to convert the system of partial differential equations into system of ordinary differential equations under the conditions defined in our model. The model has been analyzed to find the effects of various parameters such as, Hartmann number, heat source parameter and Prandtl number on the axial velocity, temperature distribution and the normal velocity. The numerical solutions of axial velocity, temperature distributions and normal velocity are shown graphically for better understanding of the problem. Hence, the present mathematical model gives a simple form of axial velocity, temperature distribution and normal velocity of the blood flow so that it will help not only people working in the field of Physiological fluid dynamics but also to the medical practitioners.

Run-Up Flow of a Maxwell Fluid through a Parallel Plate Channel

We consider the flow of an incompressible viscous Maxwell fluid between two parallel plates, initially induced by a constant pressure gradient. The pressure gradient is withdrawn and the upper plate moves with a uniform velocity while the lower plate continues to be at rest. The arising flow is referred to as run-up flow. The unsteady governing equations are solved as initial value problem using Laplace transform technique. The expression for velocity, shear stresses on both plates and discharge are obtained. The behavior of the velocity, shear stresses and mass flux has been discussed in detail with respect to variations in different governing flow parameters and is presented through graphs.

Influence of Hartmann Number on Convective Flow of Maxwell Fluid between Two Hot Parallel Plates through Porous Medium Subject to Arbitrary Shear Stress at the Boundary

Natural convection flow of unsteady Maxwell fluid with the effects of constant magnetic force in the course of a porous media is investigated in this research work. Fluid motion between a channel of parallel plates is tempted by time dependent shear stress applied on one plate. The governing partial differential equations of a model under consideration are transformed into ordinary differential equations by Laplace transform method and then solved for temperature and velocity fields. The obtained results for temperature fields are expressed in terms of complementary error function. The influences of involved parameters likes Hartmann number, Grashf number, Prandlt number and porosity parameter, on temperature and velocity profiles are shown graphically. There is no such result regarding Maxwell fluid in the existing literature.

THE PARALLEL CONFOCAL DETECTING SYSTEM USING OPTICAL FIBER PLATE

Objective Focusing on the problem such as slow scanning speed, complex system design and low light efficiency, a new parallel confocal 3D profile detecting method based on optical fiber technology, which realizes whole-field confocal detecting, is proposed. Methods The optical fiber plate generates an 2D point light source array, which splits one light beam into N2 subbeams and act the role of pinholes as point source and point detecting to filter the stray light and reflect light. By introducing the construction and working principle of the multi-beam 3D detecting system, the feasibility is investigated. Results Experiment result indicates that the optical fiber technology is applicable in parallel confocal detecting. Conclusion The equipment needn't mechanical rotation. The measuring parameters that influence the detecting can easily be adapted to satisfy different requirments of measurement. Compared with the conventional confocal method, the parallel confocal detecting system using optical fiber plate is simple in the mechanism, the measuring field is larger and the speed is faster.

ON ANALYSIS OF THE STEADY FLOW IN AN IRRECTANGULARPARALLEL-PLATE FLOW CHAMBER

The parallel-plate flow chamber (PPFC), of which the height is far smaller than its own length and width, is one of the main apparatus for the in vitro study of the mechanical behaviors of cultured cells at the bottom of PPFC undergoing shear stress. The PPFC of which the upper and lower plates are rectangular is usually used by research workers, and the flow field in this kind of PPFC (except for the regions near the entrance and exit) is uniform([1]), so only the effect the shear stress with one value has on cultured cells can be observed during each experiment. A kind of PPFC of which the upper and lower plates are not rectangular is proposed in this paper. The distributions of the velocities inside and the shear stresses at the bottom of the chamber are given by analyzing the flow field of the steady flow in the PPFC. The results show that the mechanical behaviors of cultured cells undergoing the shear stresses with various values may be simultaneously observed by the use of this kind of irrectangular PPFC. The theoretical and experimental results obtained by Ultrasonic Doppler Technique show good agreement.

Converging Parallel Plate Flow Chambers for Studies on the Effect of the Spatial Gradient of Wall Shear Stress on Endothelial Cells

Many in vitro studies focus on effects of wall shear stress (WSS) and wall shear stress gradient (WSSG) on endothelial cells, which are linked to the initiation and progression of atherosclerosis in the arterial system. Limitation in available flow chambers with a constant WSSG in the testing region makes it difficult to quantify cellular responses to WSSG. The current study proposes and characterizes a type of converging parallel plate flow chamber (PPFC) featuring a constant gradient of WSS. A simple formula was derived for the curvature of side walls, which relates WSSG to flow rate (Q), height of the PPFC (h), length of the convergent section (L), its widths at the entrance (w0) and exit (w1). CFD simulation of flow in the chamber is carried out. Constant WSSG is observed in most regions of the top and bottom plates except those in close proximity of side walls. A change in Q or h induces equally proportional changes in WSS and WSSG whereas an alteration in the ratio between w0 and w1 results in a more significant change in WSSG than that in WSS. The current design makes possible an easy quantification of WSSG on endothelial cells in the flow chamber.

Hall Current Effects on Unsteady MHD Flow in a Rotating Parallel Plate Channel Bound-ed by Porous Bed on the Lower Half—Darcy Lapwood Model

We discussed the unsteady flow of an incompressible viscous fluid in a rotating parallel plate channel bounded on one side by a porous bed under the influence of a uniform transverse magnetic field taking hall current into account. The perturbations are created by a constant pressure gradient along the plates in addition to the non-torsional oscillations of the upper plate. The flow in the clean fluid region is governed by Navier-Stoke’s equations while in the porous bed the equations are based on Darcy-Lapwood model. The exact solutions of velocity in the clean fluid and the porous medium consist of steady state and transient state. The time required for the transient state to decay is evaluated in detail and ultimate quasi-steady state solution has been derived analytically and also its behaviour is computationally discussed with reference to different flow parameters. The shear stresses on the boundaries and the mass flux are also obtained analytically and their behaviour is computationally discussed.

Hall Effects on Unsteady MHD Three Dimensional Flow through a Porous Medium in a Rotating Parallel Plate Channel with Effect of Inclined Magnetic Field

In this paper, we make an initial value investigation of the unsteady flow of incompressible viscous fluid between two rigid non-conducting rotating parallel plates bounded by a porous medium under the influence of a uniform magnetic field of strength H0 inclined at an angle of inclination α with normal to the boundaries taking hall current into account. The perturbations are created by a constant pressure gradient along the plates in addition to the non-torsional oscillations of the upper plate while the lower plate is at rest. The flow in the porous medium is governed by the Brinkman’s equations. The exact solution of the velocity in the porous medium consists of steady state and transient state. The time required for the transient state to decay is evaluated in detail and the ultimate quasi-steady state solution has been derived analytically. Its behaviour is computationally discussed with reference to the various governing parameters. The shear stresses on the boundaries are also obtained analytically and their behaviour is computationally discussed.

PARALLEL FINITE ELEMENT ANALYSIS OF HIGH FREQUENCY VIBRATIONS OF QUARTZ CRYSTAL RESONATORS ON LINUX CLUSTER

Quartz crystal resonators are typical piezoelectric acoustic wave devices for frequency control applications with mechanical vibration frequency at the radio-frequency （RF） range. Precise analyses of the vibration and deformation are generally required in the resonator design and improvement process. The considerations include the presence of electrodes, mountings, bias fields such as temperature, initial stresses, and acceleration. Naturally, the finite element method is the only effective tool for such a coupled problem with multi-physics nature. The main challenge is the extremely large size of resulted linear equations. For this reason, we have been employing the Mindlin plate equations to reduce the computational difficulty. In addition, we have to utilize the parallel computing techniques on Linux clusters, which are widely available for academic and industrial applications nowadays, to improve the computing efficiency. The general principle of our research is to use open source software components and public domain technology to reduce cost for developers and users on a Linux cluster. We start with a mesh generator specifically for quartz crystal resonators of rectangular and circular types, and the Mindlin plate equations are implemented for the finite element analysis. Computing techniques like parallel processing, sparse matrix handling, and the latest eigenvalue extraction package are integrated into the program. It is clear from our computation that the combination of these algorithms and methods on a cluster can meet the memory requirement and reduce computing time significantly.

钢板削弱型叠层橡胶支座力学性能试验研究

结合厚层橡胶支座和普通叠层橡胶支座的优点设计新型钢板削弱型叠层橡胶支座,通过调节环形钢板的总数和位置进行支座水平和竖向刚度的有效控制.选择3种中心橡胶层厚度的钢板削弱型叠层橡胶支座,分析所设计支座的滞回特性、刚度特性和耗能特性.基于串-并联模型,构建水平和竖向刚度的计算模型.试验结果表明,相比普通叠层橡胶支座,钢板削弱型叠层橡胶支座的水平和竖向刚度更低,水平和竖向耗能比更高,滞回曲线更光滑饱满.所建模型的计算结果与试验结果的一致性较好,误差绝对值不超过10%.所建模型在评估钢板削弱型叠层橡胶支座的水平和竖向刚度方面具有较高的精度和适用性.

表面平齐的并联微穿孔板吸声结构特性仿真研究

针对火箭发动机燃气高温高速射流通道内噪声控制的工程需要,提出了一种表面平齐的并联微穿孔板吸声结构设计方案。基于微穿孔板吸声理论,建立了COMSOL微穿孔板吸声结构吸声性能仿真模型,对该类并联微穿孔板吸声结构的吸声特性进行了仿真研究,分析了并联结构的背腔深度比、周期和单体宽度等多种参数对吸声性能的影响。结果表明,通过合理选择微穿孔板参数,以及并联共振腔深度、周期比、单体宽度等参数,可以得到吸声带宽、吸声系数较优的吸声结构,且加工制造与安装维护简单,研究成果可用于高温高速射流通道内的强噪声辐射环境控制。

平行板微通道中一类不可压缩微极性流体在高Zeta势下的时间周期电渗流

在高Zeta势下,研究平行板微通道中一类不可压缩微极性流体的时间周期电渗流.在不使用DebyeHüickel线性近似条件下,利用有限差分法数值求解非线性Poisson-Boltzmann方程和不可压缩微极性流体的连续性方程、动量方程、角动量方程及本构方程,在低Zeta势下将所得结果与使用Debye-Hückel线性近似得到的解析解比较,证明本文数值方法是可行的;讨论高Zeta势下电动宽度m、电振荡频率Ω、微极性参数k1等无量纲参数对不可压缩微极性流体的速度和微旋转效应的影响.研究表明:1)随着Zeta势的增大,微极性流体的速度、微旋转、体积流量、微旋强度以及剪切应力增大,说明与低Zeta势相比,高Zeta势对微极性流体电渗流有显著的促进作用.2)在高Zeta势下,随着微极性参数的增大,微极性流体的速度减小,但是对微旋转效应呈现先增强后减弱的趋势.3)在高Zeta势下,当电振荡频率较低(小于1)时,电动宽度的增大促进微极性流体的流动,但抑制其微旋转;当电振荡频率较高(大于1)时,电动宽度的增大抑制微极性流体的流动及微旋转,但促进体积流量快速增大并趋于恒定.4)在高Zeta势下,当电振荡频率较低(小于1)时,微极性流体电渗流速度和微旋转随着电振荡频率的变化呈现明显的振荡变化趋势,但是速度和微旋转的峰值、体积流量及微旋强度均保持不变;当电振荡频率较高(大于1)时,随着电振荡频率的增大,微极性流体电渗流速度和微旋转的幅值减小,体积流量及微旋强度减小直至趋于零.5)在高Zeta势下,壁面剪切应力σ21及σ12的幅值随电动宽度的增大而增大;当电振荡频率较低(小于1)时,壁面剪切应力σ21与σ12不随电振荡频率的增大而变化,均取恒定值,且微极性参数的取值不影响壁面剪切应力σ21的幅值;当电振荡频率较高(大于1)时,壁面剪切应力σ21及σ12的幅值随电振荡频率的增大而减小,且壁面剪切应力σ21的幅值随着微极性参数的增大而减小,而壁面剪切应力σ12的振幅随着微极性参数的增大而线性减小.

基于标准场法的低频电场计量技术探讨

为了实现低频电场测量仪的校准,探讨了基于标准场法的低频电场计量技术。描述了低频电场测量仪的结构和工作原理,分析了应用平行板产生可计算标准电场的方法,研究构建了校准系统。应用该系统进行了校准测量实验,分析了测量误差来源,评估了测量结果的不确定度。将实验结果与应用横电磁波室法的测量结果作了比较,数据表明该校准系统的测量结果合理,满足低频电场测量仪的校准要求。

金属盖板镀层形貌对平行缝焊器件抗盐雾性能的影响

气密性封装是高可靠集成电路制造的关键技术。探讨了金属盖板表面镀层形貌对平行缝焊器件耐盐雾性能的影响。研究发现,平行缝焊后金属盖板表面出现的贯穿性裂纹是降低平行缝焊器件耐盐雾性能的关键因素。在相同封帽参数下,表面镀层为长条形晶胞的盖板封帽后出现多条贯穿性裂纹,无法通过24 h盐雾试验后气密性检测。而表面镀层为均匀大小的圆形晶胞的盖板具备更高的抗封帽裂纹能力,封帽后无贯穿性裂纹出现,且可通过48 h盐雾试验后气密性检测。