Partial slip effect on non-aligned stagnation point nanofluid over a stretching convective surface

The present study inspects the non-aligned stagnation point nano fluid over a convective surface in the presence of partial slip. Two types of base fluids namely water and kerosene are selected with Cu nanoparticles. The governing physical problem is presented and transformed into a system of coupled nonlinear differential equations using suitable similarity transformations. These equations are then solved numerically using midpoint integration scheme along with Richardson extrapolation via Maple. Impact of relevant physical parameters on the dimensionless velocity and temperature profiles are portrayed through graphs. Physical quantities such as local skin frictions co-efficient and Nusselt numbers are tabularized.It is detected from numerical computations that kerosene-based nano fluids have better heat transfer capability compared with water-based nanofluids. Moreover it is found that water-based nanofluids offer less resistance in terms of skin friction than kerosene-based fluid. In order to authenticate our present study, the calculated results are compared with the prevailing literature and a considerable agreement is perceived for the limiting case.

Transient Hydromagnetic Stagnation-Point Flow across a Vertical Surface with Partial Slip in a Chemically Reactive Medium

A numerical study of partial slip boundary condition is investigated. The stagnation-point flow problem involving some physio-chemical parameters has been elucidated. The process involves developing a multivariate mathematical model for the flow and transforming it into a coupled univariate equation. Key parameters of interest in the study are the buoyancy force, the surface stretching, the unsteadiness, the radiation, the dissipation effects, the slip effects, the species reaction and the magnetic field parameters. It is concluded that the impact of physio-chemical factors significantly alters the kinematics of the flow in order to optimally achieve desired product characteristics.

Effects of partial slip on flow of a third grade fluid

This paper is an analytical study of the rotating flow of a third grade fluid past a porous plate with partial slip effects. It serves as a flow model for the study of polymers. The analytic solution has been determined using homotopy analysis method （HAM）.

Surface Oxidation and Subsurface Microstructure Evolution of Alloy 690TT Induced by Partial Slip Fretting Corrosion in High-Temperature Pure Water

The surface oxidation and subsurface microstructure evolution of Alloy 690 TT can occur during partial slip fretting corrosion in high-temperature pure water.Detailed characterization methods such as laser scanning confocal microscopy,scanning electron microscopy,electron probe micro-analyzer,and transmission electron microscopy were used to reveal the related mechanism.The results showed that Cr_(2)O_(3) oxides together with a small number of spinel oxides were formed in sticking region since a small quantity of high-temperature water could pass through the gaps between the asperities to oxidize the materials.Widespread distribution of oxides in microslip region consisted of(Ni,Fe)Cr_(2)O_(4),because Ni^(2+)and Fe^(2+) ions could react with Cr_(2)O_(3) to generate a small amount of non-stoichiometric spinel oxides.The oxides around micropitting in microslip region consisted of double-layer structure.The outermost layer contained(Fe,Cr)-rich oxides due to the effect of fretting leading to mechanical mixing between Cr_(2)O_(3) and(Ni,Fe)(Fe,Cr)_(2)O_(4).The inner layer consisted of(Fe,Ni)-rich oxides owing to the consumption of Cr_(2)O_(3) by the reaction with Ni^(2+)and Fe^(2+) ions.The reciprocating motion of oxide particles in microslip region resulted in the stress-strain supporting the recrystallization for the formation and development of a tribologically transformed structure in subsurface and plowing effect by fretting in surface.

Impact of partial slip condition on mixed convection of nanofluid within lid-driven wavy cavity and solid inner body

In thermofluid systems,the lid-driven square chamber plays an imperative role in analyzing thermodynamics’first and second laws in limited volume cases executed by sheer effects with a prominent role in many industrial applications including electronic cooling,heat exchangers,microfluidic components,solar collectors,and renewable energies.Furthermore,nanofluids as working fluids have demonstrated potential for heat transfer enhancement systems,however there are some concerns about irreversibility problems in the systems.Due to this problem and in line with the applications of partial slip on fluid flow modification and irreversibilities,the present study considers laminar mixed convection and entropy generation analysis of aluminum oxide nanofluid inside a lid-driven wavy cavity having an internal conductive solid body in the presence of a partial slip on the upper surface,which to the best of our knowledge,has not been investigated so far.The fundamental equations of the current work with the appropriate boundary conditions are first made dimensionless and then solved numerically using the Galerkin weighted residual FEM.The main parameters of the flow and heat transfer,entropy generation,and Bejan number are presented and explained in details.The outcomes indicate that the partial slip is more effective when friction irreversibilities govern the cavity.In the presence of slip condition,the flow circulation changes the trend in the middle of the cavity around the solid block leading to a decrease in the isentropic lines at the dense sections with almost 30%less than the case of no-slip condition.It is concluded that partial slip shows different trends on the local Nusselt number interface along the wavy wall improving the average Nusselt number where high friction irreversibilities dominate.

Effects of slip, viscous dissipation and Joule heating on the MHD flow and heat transfer of a second grade fluid past a radially stretching sheet

The flow and heat transfer of an electrically conducting non-Newtonian second grade fluid due to a radially stretching surface with partial slip is considered. The partial slip is controlled by a dimensionless slip factor, which varies between zero （total adhesion） and infinity （full slip）. Suitable similarity transformations are used to reduce the resulting highly nonlinear partial differential equations into ordinary differential equations. The issue of paucity of boundary conditions is addressed and an effective numerical scheme is adopted to solve the obtained differential equations even without augmenting any extra boundary conditions. The important findings in this communication are the combined effects of the partial slip, magnetic interaction parameter and the second grade fluid parameter on the velocity and temperature fields. It is interesting to find that the slip increases the momentum and thermal boundary layer thickness. As the slip increases in magnitude, permitting more fluid to slip past the sheet, the skin friction coefficient decreases in magnitude and approaches zero for higher values of the slip parameter, i.e., the fluid behaves as though it were inviscid. The presence of a magnetic field has also substantial effects on velocity and temperature fields.

Blasius flow and heat transfer of fourth-grade fluid with slip

This investigation deals with the effects of slip, magnetic field, and non- Newtonian flow parameters on the flow and heat transfer of an incompressible, electrically conducting fourth-grade fluid past an infinite porous plate. The heat transfer analysis is carried out for two heating processes. The system of highly non-linear differential equations is solved by the shooting method with the fourth-order Runge-Kutta method for moderate values of the parameters. The effective Broyden technique is adopted in order to improve the initial guesses and to satisfy the boundary conditions at infinity. An exceptional cross-over is obtained in the velocity profile in the presence of slip. The fourth-grade fluid parameter is found to increase the momentum boundary layer thickness, whereas the slip parameter substantially decreases it. Similarly, the non-Newtonian fluid parameters and the slip have opposite effects on the thermal boundary layer thickness.

Numerical Solution for Variable Accelerated Flow Subject to Slip Effect

In this paper, we examine the unsteady magneto hydrodynamic (MHD) flow generated by a disc that is making non-coaxial rotations with a third grade fluid at infinity and moving with a variable acceleration. The fluid is assumed to satisfy slip boundary condition on the disc. The governing equations are three dimensional and highly non-linear in nature. The assumed slip boundary condition is non-linear as well. The governing equations are transformed to a nonlinear boundary value problem which is solved numerically. Comparison of this generalized problem with uniformly accelerated disk satisfying no slip condition is made. Variations of the characterizing dimensionless parameters such as slip parameter λ, acceleration parameter c, unsteady parameter τ, third grade parameter β, suction parameter S, and magnetic parameter N on the flow field are discussed and analyzed graphically.

CALCULATION ANALYSIS OF SHEARING SLIP FOR STEEL-CONCRETE COMPOSITE BEAM UNDER CONCENTRATED LOAD

The strain difference of steel and concrete under vertical concentrated load was analyzed on the basis of elastic theory, and was compared with ideal solution of steel and concrete under vertical uniform load. The results indicate that the computing formula concluded from the paper is believable. The practical structure usually bears concentrated load, so it can be used in the practical engineering.

Constraints on rupture speed of the 2001 MS 8.1 West Kunlun Mountain Pass earthquake by co-seismic surface rupture slip displacements based on the slip-weakening mechanism with frictional undershoot involved

With co-seismic surface rupture slip displacements provided by the field observation for the 2001 MS8.1 West Kunlun Mountain Pass earthquake, this paper estimates the rupture speed on the main faulting segment with a long straight fault trace on the surface based on a simple slip-weakening rupture model, in which the frictional overshoot or undershoot are involved in consideration of energy partition during the earthquake faulting. In contrast to the study of Bouchon and Vallée, in which the rupture propagation along the main fault could exceed the local shear-wave speed, perhaps reach the P-wave speed on a certain section of fault, our results show that, under a slip-weakening assumption combined with a frictional undershoot (partial stress drop model), average rupture speed should be equal to or less than the Rayleigh wave speed with a high seismic radiation efficiency, which is consistent with the result derived by waveform inversion and the result estimated from source stress field. Associated with the surface rupture mechanism, such as partial stress drop (frictional undershoot) associated with the apparent stress, an alternative rupture mechanism based on the slip-weakening model has also been discussed.

弹性接触中的表面微滑问题及数值求解

研究法向载荷和切向载荷耦合作用下的三维弹性点接触问题。当切向载荷不足使接触体发生整体滑动时,接触面产生微滑区域。对于异质物体的接触,即使仅有法向载荷作用,由于变形的不协调,接触面同样会产生微滑区域。运用半解析的方法求解微滑接触问题,影响系数通过Green函数得到解析解,压力和切应力的求解基于共轭梯度法和快速傅里叶变换法。算法仅在关心的接触区域划分网格,缩短计算时间。通过对比光滑同质物体接触的数值解和解析解来验证算法。分析正弦异质表面接触的压力分布、切应力分布、粘着区域。结果显示,由于粗糙峰的存在,粘着区域为多个不连通的区域。随着切向力的增加,压力分布沿着切向力相反的方向倾斜,切应力τx逐步变为正值,粘着区域沿着切向力相反的方向移动并逐渐变小。

TC4合金微动磨损部分滑移区摩擦参数的演变

选取三种硬度对偶件(HV680GCr15、HV1500Si_(3)N_(4)和HV2300Al_(2)O_(3))为变量,研究TC4合金在室温和高温下微动磨损部分滑移区摩擦特性参数的演变。试验结果表明,在三种硬度对偶件配合下,TC4合金在室温和高温下的微动磨损均处于典型部分滑移区,未发生向其他两区域的转变。对偶件硬度对部分滑移区摩擦特性参数的影响较为显著:对偶件硬度对表面损伤的影响最为突出,磨痕表面由清晰可辨的黏着与微滑两区逐渐转变为黏着、微滑以及严重塑性变形的环状过渡区,表面轮廓由凹凸峰曲线转变为中心明显凹坑、边缘较为粗糙的规则“U”型斑;对偶件硬度对损伤机制的影响较小,由黏着磨损逐渐过渡到氧化伴随黏着磨损;对偶件硬度对摩擦系数几乎不产生影响,曲线变化规律,稳定值基本相同。

集中荷载作用下组合梁剪切滑移计算分析

基于弹性理论,对钢_混凝土组合梁在竖向集中荷载作用下的剪切滑移应变差进行了理论分析,并与均布荷载作用下公认的理论解进行了计算对比· 结果表明,所推导的在集中荷载作用下,钢_混凝土组合梁的剪切滑移应变差的计算公式是可信的· 因为实际工程多为集中荷载作用。

组合桁架内力和变形的有限元计算与测试比较

为验证组合桁架有限元模型的准确性，寻求组合桁架内力和变位的分布规律，提供实际设计依据，对两榀测试组合桁架的内力、滑移、掀起和挠度进行电算和实测，电算值与实测值吻合良好。

温差影响下的局部滑移接触行为的研究

针对不同温度装配件间接触界面的局部滑移问题,建立了三维稳态热弹性局部滑移接触的半解析求解模型.基于热弹性理论与热传导方程,构建了半空间受热流载荷和力载荷作用下的频响函数并建立了相应的影响系数矩阵.借助离散卷积-快速Fourier变换等数学工具,实现了针对高温压头与热弹性半空间局部滑移接触问题的高效求解.接触界面间的热量传递满足Fourier热传导定律,并且黏/滑状态由Coulomb定律确定.基于该半解析模型分析了不同荷载及温差对表面法向压力分布、摩擦力分布、刚体位移及接触区黏/滑演化行为的影响.研究结果表明,当法向荷载和切向荷载一定时,温差的上升会导致接触区域的减小,引起接触面法向压力及摩擦力的峰值增大,并且会显著影响黏着区与滑移区的分布情况.

囊谦盆地新生代钾质火山岩成因岩石学研究

囊谦新生代钾质火山岩形成于碰撞后的板内构造环境 ,基性、中性和中酸性熔岩之间不存在分异和演化的关系 ,它们地球化学性质上的差异是源区部分熔融程度不同所致 ;钾质岩浆形成于 50～ 80km深处的富集交代地幔。横断山地区一些拉分盆地中火山岩源区的部分熔融可能与来自软流圈小而分散的上涌体的底侵有关。

钢-砼组合桁架部分交互作用理论分析

目前组合结构设计计算中有关组合梁的部分交互作用理论均忽略掀起影响率先在组合桁架中同时考虑滑移和掀起影响，推导出关于轴力Ｆ（ｘ）的六次线性非齐次微分方程。

部分剪力连接新型外包钢-砼组合梁的滑移性能

针对典型的钢-砼组合梁的不足,提出一种新型外包钢-砼组合梁.为研究其钢-砼交界面相对滑移及变形性能,通过4根足尺简支梁的试验研究,得到组合梁的荷载-滑移、荷载-挠度关系曲线.根据试验结果分析了新型外包钢-砼组合梁交界面相对滑移发展的过程和分布规律.利用有限元分析软件ANSYS,对组合梁的交界面相对滑移性能进行了非线性有限元分析,提出剪力连接系数的合理范围.在基于现行规范的基础上提出了组合梁跨中挠度的建议计算公式.把有限元模型和建议公式的计算结果与试验结果进行比较,三者吻合良好.

部分共同作用框架组合梁有限元分析模型

本文提出了一种新的适用框架整体分析的组合梁有限元模型。在分析了相互作用程度对组合梁刚度影响的基础上,根据Newmark等人的一维部分相互作用理论,建立起部分共同作用组合梁平衡微分方程;结合框架组合梁受力特点引入合理的边界条件,推导出了能够考虑滑移的组合梁单元弹性刚度方程;还给出了常见非节点荷载的等效荷载公式。该组合梁单元节点自由度少,每个构件只需一个单元来模拟,方便了带组合梁钢框架的结构分析。本文的研究还为进一步地考虑混凝土开裂、压碎,钢材屈服等非线性因素,建立组合梁单元弹塑性刚度矩阵提供了理论基础。

桩土滑移对桩基临界荷载影响

为了研究打(压)桩时桩侧土体液化导致的桩土相对滑移对桩基临界荷载的影响,采用部分滑移模型,将桩周土分为桩土滑移区域和结合区域,并将二区域的应力分别表示,根据桩土滑移区域和结合区域的应力和荷载的连续性,得到了桩土滑移段的长度,可用以对桩基临界荷载进行修正.结果表明,桩土相对滑移对桩基临界荷载影响较大.