Partial Slip Research Articles

Dual Solutions of Boundary Layer Flow and Heat Transfer in Hybrid Nanofluid over a Stretching/Shrinking Cylinder

The boundary layer flow over a stretching/shrinking cylinder in hybrid nanofluid with the effects of suction, partial slip and convective boundary condition is studied. Hybrid nanoparticles Al2O3 and TiO2 with water as based fluid are considered in the study. The partial differential equations are transformed to ordinary differential equations by employing the similarity variables. The numerical results are obtained using the bvp4c solver in MATLAB software. The influence of nanoparticles volume fraction (Al2O3-TiO2 in water-based fluid), curvature parameter, suction parameter, partial slip parameter and Biot number on the velocity profile, temperature profile, skin friction coefficient and heat transfer rate are discussed. The numerical results indicate that for shrinking surface case, the dual solutions exist for a certain range of curvature parameter and suction parameter.

Partial Slip Effects on MHD Peristaltic Flow of Carreau-Yasuda Fluid (CY) Through a Planner Micro-Channel

In modern applied mathematics, engineering, and the physiological world, the concept of peristalsis is of great significance. The present article concentrates on the peristaltic movement of Carreau-Yasuda fluid through planner micro-channel under the influence of applied magnetic field and partial slip conditions. The governing system of equations are nondimensionalized and transformed using basic assumptions such as long wavelength and low Reynolds number. A bulti-in route "ND solve" in Mathematica exercised to solve obtained nonlinear coupled equations with appropriate boundary conditions. Obtained results are elucidated by plotting graphs for different physiological constraints such as velocity, temperature, and concentration. Physical characteristics such as skin friction, Nusselt number and Sherwood number are discussed via table results. The typical character of this work e.g. flow index parameter exhibits that the apparent fluid viscosity becomes high when it has a higher value due to which fluid faces more resistance and the presence of a higher magnetic effect predicts the decreasing behavior on velocity. Additionally, the trapping phenomenon explains bolus movement and are discussed briefly.

Exploring the Dynamics of Second-Grade Fluid Motion and Heat Over a Deforming Cylinder or Plate Affected by Partial Slip Conditions

Exploring the Dynamics of Second-Grade Fluid Motion and Heat Over a Deforming Cylinder or Plate Affected by Partial Slip Conditions

Boundary layer formations over a stretchable heated cylinder in a viscoelastic fluid with partial slip and viscous dissipation effects

An exact similarity solution is worked out for fluid motion in the vicinity of a cylindrical surface in an electrically conducting viscoelastic fluid obeying the Jeffrey model. Cylindrical surface expands axially with linear velocity and has a prescribed surface temperature. The present analysis focuses on the partial slip assumption which gives rise to a nonlinear case Robin-type (mixed) boundary condition in axial velocity. In contrast to a previously published study (J. Mech., vol 31, pp. 69–78, 2015) which only reported local similarity solutions in no-slip case, the present work provides an exact similarity analysis by defining a quadratic surface temperature. The effects of the magnetic field and Joule heating on the momentum and thermal transport phenomena are also scrutinized. A numerical routine is used to solve the equation accurately for a wide range of fluid parameters, including ranges that could not be handled by previous approximate analytical methods that were limited to the no-slip limit. The influences of viscoelasticity and partial slip on the flow behavior are investigated, and the coefficient of skin friction for a Jeffrey fluid is calculated. Obtained results are consistent with the previously published works under special situations. The case of flat surface, which can be obtained as a limiting case of the model, is not even explored in the past.

Partial Slip Effects for Thermally Radiative Convective Nanofluid Flow

The partial slip effects for radiative convective nanofluid flow over a stretching sheet in porous medium are analytically explored in this work. The Navier–Stokes equations, the momentum and the energy equations are converted into a set of non-linear ODEs by the similarity transformation. Using the modified optimal homotopy asymptotic method (OHAM), the resulting non-linear ODEs are analytically approximately solved. The impact of various parameters, such as: the velocity exponential factor n, the wall thickness parameter γ, the dimensionless velocity slip parameter δ1, the Prandtl number Pr, the radiation parameter R, and the dimensionless temperature jump parameter δ2, on the behaviour of the mass and heat transfer is presented. The influence of these parameters is tabular and graphically presented. An excellent agreement between the approximate analytical solution and the corresponding numerical solution is highlighted. The results obtained confirm that modified OHAM is a useful and competitive mathematical tool to explore a large class of non-linear problems with applications in various fields of science and engineering.

Dynamics of Brownian motion and nonlinear mixed convective conditions on thermophoretic slip flow embedded with non-Fourier flux

In this paper, the importance of mass and heat transfer characteristics of mixed convective conditions on nonlinear free convection flow embedded with non-Fourier flux and thermal radiation is numerically investigated. A partial Casson slip and mixed impact of thermophoresis and Brownian motion is considered at the elastic surface. To change the highly nonlinear partial differential equations into ordinary differential system, we used the similarity transformations and then the shooting method is employed to solve resulting equations. The significance of various physical parameters on the velocity, concentration and temperature profiles are investigated for both negative value of ferromagnetic interaction ([Formula: see text]) and positive value of ferromagnetic interaction ([Formula: see text]). The governing physical aspects of coefficient of skin friction, the Sherwood and Nusselt numbers are obtained for various embedded parameters. Our findings concluded that the ferromagnetic interaction is positive and then more mass transfer rate is identified compared to the negative value of ferromagnetic interaction, but whereas in friction and heat transfer rate, it was completely mixed sense (i.e., different effects have different results). Brownian motion has less Nusselt number values in positive ferromagnetism compared to negative ferromagnetism and quite opposite behavior is observed in the presence of thermophoresis, this happened due to nonlinear flux and buoyancy.

Radiation Effects on Boundary Layer Flow and Heat Transfer of the Power Law Fluid Over a Stretching Cylinder with Convective Boundary Conditions

In this work, a power law fluid model is used to examine the boundary layer flow and heat transfer characteristics over an unsteady horizontal stretching cylinder under the influence of convective boundary conditions. It is presumed that partial slip conditions exist and that the thermal conductivity of the nanofluid is a function of temperature at the boundary. Through similarity transformation, the coupled partial differential equations are converted into ordinary differential equations (ODEs), which are then resolved in MATLAB with BVP4C. By contrasting the computed findings with the published results, the validity of the results is proven. The effects of different parameters on the temperature and velocity profiles are carefully looked at and analysed. As the Eckert number increases, the thermal boundary layer thickens. All of the physical factors that affect the local Nusselt number and skin friction coefficient have been studied carefully and are shown in the tables.

Fretting corrosion behavior of Ti6Al4V alloy against zirconia-toughened alumina ceramic in simulated body fluid

The fretting corrosion at the head-neck interface of artificial hip joints is an important reason for the failure of prostheses. The Ti6Al4V alloy-zirconia-toughened alumina (ZTA) ceramic combination has been widely used to make the head and neck of artificial hip joints. In this study, its fretting corrosion behavior in simulated body fluid was studied by electrochemical monitoring, surface morphology characterization, and chemical composition analysis. A running condition fretting map (RCFM) of load and displacement was established, including three regimes, namely partial slip regime (PSR), mixed fretting regime (MFR), and gross slip regime (GSR). The friction dissipation energy increased gradually from the PSR to MFR and GSR. In the PSR, the damage mechanisms were slight abrasive wear and tribocorrosion at the edge of contact area, as well as extremely slight adhesive wear at the center. In the MFR, the damage mechanisms were mainly adhesive wear, abrasive wear, and corrosive wear. In the GSR, the damage mechanism was serious abrasive wear, fatigue wear, and corrosive wear combined with slight adhesive wear. Finally, an ion-concentration map was created, displaying the material-loss transition of different displacements and loads. The material loss increased with the increased displacement, and increased first and then decreased with the increased load.

Influence of iron dilution on plastic deformation mechanisms in cobalt-based alloys: Consequence of phase transformations on tribological behavior

The chemical composition and microstructure of metallic parts are parameters that affect plastic deformation accommodation mechanisms under friction stresses. The content of alloying elements impacts the stacking fault energy and the plastic deformation, and thus affects the tribological behavior. Depending on this content and the levels of mechanical stresses, plastic deformation of some alloys obtained under non-equilibrium conditions can occur. It is caused by different mechanisms, such as perfect slip and/or partial dislocation slip, as well as by phase transformation. The purpose of this study is to determine the influence of the plastic deformation accommodation mechanisms on tribological behavior by studying the effect of the iron content in cobalt-based alloys. For manufacturing purposes, cobalt-based coatings are produced on steel substrate using a additive manufacturing process (SLM). With this process, the microstructures of the cobalt-based coatings are essentially metastable FCC phase at room temperature with different contents of diluted iron. Tribological tests were carried out with a ball-to-disc contact. Iron contents were estimated by EDS-SEM. Analytical techniques such as XRD and EBSD were used to identify the microstructural changes observed in TTS due to tribological loading. The friction coefficient is linked to the evolution of the plastic deformation mechanisms activated to accommodate the contact. In particular, in addition to work-hardening phenomena, phase transformations are possible, namely a metastable FCC phase gives an HCP phase and a metastable FCC phase gives an α′-BCC phase under tribological loading. Both types of transformations can occur, individually or simultaneously, depending on the iron content in the coating.

Biomechanics of the finger pad in response to torsion.

Surface skin deformation of the finger pad during partial slippage at finger-object interfaces elicits firing of the tactile sensory afferents. A torque around the contact normal is often present during object manipulation, which can cause partial rotational slippage. Until now, studies of surface skin deformation have used stimuli sliding rectilinearly and tangentially to the skin. Here, we study surface skin dynamics under pure torsion of the right index finger of seven adult participants (four males). A custom robotic platform stimulated the finger pad with a flat clean glass surface, controlling the normal forces and rotation speeds applied while monitoring the contact interface using optical imaging. We tested normal forces between 0.5 N and 10 N at a fixed angular velocity of 20° s-1 and angular velocities between 5° s-1 and 100° s-1 at a fixed normal force of 2 N. We observe the characteristic pattern by which partial slips develop, starting at the periphery of the contact and propagating towards its centre, and the resulting surface strains. The 20-fold range of normal forces and angular velocities used highlights the effect of those parameters on the resulting torque and skin strains. Increasing normal force increases the contact area, the generated torque, strains and the twist angle required to reach full slip. On the other hand, increasing angular velocity causes more loss of contact at the periphery and higher strain rates (although it has no impact on resulting strains after the full rotation). We also discuss the surprisingly large inter-individual variability in skin biomechanics, notably observed in the twist angle the stimulus needs to rotate before reaching full slip.

Roll of partial slip on Ellis nanofluid in the proximity of double diffusion convection and tilted magnetic field: Application of Chyme movement

The current study aims to investigate the effect of partial slip conditions over double diffusion convection. The phenomenon is applied with the inclined magnetic flux of peristaltic flow on Ellis nanofluid model in an asymmetric channel. The fundamental differential equations are constructed and solved through lubrication approximation that gives the coupled system of ordinary differential equations. This resultant system is further solved numerically, and graphic representation are used to physically comprehend the flow quantity data. The whole procedure is carried out under the trapping mechanism by drawing contour streamlines. The knowledge gained from this work will be useful in the creation of intelligent magneto-peristaltic pumps for specific heat and medication delivery phenomena.

Nano-structuring of a high entropy alloy by severe plastic deformation: Experiments and crystal plasticity simulations

The evolution of microstructure, texture, and mechanical properties of an induction melted non-equiatomic Al6Co23.5Fe23.5Mn23.5Ni23.5 (at.%) high entropy alloy subjected to severe plastic deformation was investigated experimentally and by simulations. Analyses using electron backscatter diffraction and transmission Kikuchi diffraction images revealed the evolution of the microstructures. The coarse-grained initial structure was deformed down to an average grain size of 50 nm after a shear strain of 11 by employing the high-pressure compressive shearing process, at room temperature. Transmission electron microscopy analysis showed the presence of nano-twins. The high deformation led to a significant increase in the strength, up to ≈ 1.0 GPa. X-ray diffraction macro-texture analysis revealed a shear texture with the dominance of the B/B¯{112}110-type component whose intensity varied with strain. A two-step Taylor-type polycrystal plasticity simulation approach reproduced the texture by a correlation value of 91%. In the first part of the modeling, grain fragmentation was simulated, while in the second part, grain boundary shearing and deformation twinning were considered together with the operation of {111}112-type partial slip. The effect of twinning was also examined in the texture modeling and the simulations estimated that its fraction was less than 2%.

Outcomes of Partial Slip on Double-Diffusive Convection on Peristaltic Waves of Johnson–Segalman Nanofluids Under the Impact of Inclined Magnetic Field

Outcomes of Partial Slip on Double-Diffusive Convection on Peristaltic Waves of Johnson–Segalman Nanofluids Under the Impact of Inclined Magnetic Field

Theortical study of temperature-dependent flow induced by MW model

A theoretical study is examined by taking the effects of the boundary layer flow over a heated rotating disk for both anisotropic and isotropic surfaces. We used the Carreau fluid model for shear thinning and thickening behaviors and determine the steady flow profiles under the partial slip model. Thermal conductivity and mass diffusivity are adopted to explore the flow phenomena. Numerical solution of the boundary layer equation is then preformed by using a shooting technique. Thermal conductivity and mass diffusivity increase the temperature and concentration profiles. We determine the base flow profiles and give a physical explanation of the problem though figures and tables. This study explores the interesting physical parameters on the base flow, heat and mass transfer profiles. Comparison has been made with the present results of the literature, achieving a good agreement.

Underlying slip/twinning activities of Mg-xGd alloys investigated by modified lattice rotation analysis

The inconsistencies regarding the fundamental correlation between Gd content and slip (twinning) activities of Mg alloys appeal further investigations. However, the traditional slip dislocations analysis by TEM is time-consuming, and that by SEM/EBSD cannot recognize the partial slip modes. These urge a more efficient and comprehensive approach to easily distinguish all potential slip modes occurred concurrently in alloy matrix. Here we report a modified lattice rotation analysis that can distinguish all slip systems and provide statistical results for slip activities in Mg alloy matrix. Using this method, the high ductility of Mg-Gd alloy ascribed to the enhanced non-basal slips, cross-slip, and postponed twinning activities by Gd addition is quantitatively clarified.

Towards a predictive, physics-based friction model for the dynamics of jointed structures

Bolted connections are ubiquitous in mechanical designs and pose a significant challenge to understanding and predicting the vibration response of assembled structures. The present paper develops a physics-based rough contact model of the frictional interactions within a joint. This model sums over the probable interactions of asperities – defined as locally maximum surface features – to determine the contact forces. Here, the tangential contact forces vary smoothly between sticking and slipping and allow the model to better capture the qualitative trends of experimental amplitude dependent frequency and damping than previous studies. Furthermore, the novel model is generalized to allow for arbitrarily varying normal pressure including potential separation to better represent the interfacial dynamics. This includes developing a new, computationally tractable approximation to the analytical Mindlin partial slip solution for tangential loading of contacting spheres. The results highlight the importance of accurately characterizing the as-built topology of the interface, the plastic behavior of the contacting asperities, the relevant length scale of asperities, and the eccentricity of asperities. A predictive friction coefficient based on plasticity provides a poor match to experiments, so fitting the friction coefficient is also considered. Numerical results are compared to experiments on the Brake-Reuß Beam to assess the predictive potential of the models. While blind predictions over-predict the slip limit, the current model presents a significant improvement in physics-based modeling and highlights areas for ongoing research.

High-speed nanoscale tribology enabled by combined QCM/AFM

Forming a fundamental understanding of tribological processes on the atomic scale has the potential to revolutionize the control of friction and wear in macroscopic mechanical systems. On the other hand, methods such as atomic force microscopy (AFM) that provide nanoscale spatial resolution are severely limited in terms of scanning speed when compared with macroscopic mechanical processes, leading to a “speed gap” between fundamental and applied tribology that spans several orders of magnitude. Here, we propose a new method combining AFM experiments with simultaneous quartz crystal microbalance (QCM) measurements for high-speed nanoscale tribology. In particular, scanning speed and vibration amplitude are controlled by QCM whereas normal loads are controlled by AFM. Complementary data are simultaneously recorded in the form of nanoscale, two-dimensional maps of frequency shifts and lateral forces provided by the QCM and AFM, respectively. Proof-of-principle results are presented on a gold-coated QCM sensor surface patterned with a graphene array, whereby stick and partial slip regimes are observed as a function of sliding speed.

Entropy optimized flow of hybrid nanofluid with partial slip boundary effects and induced magnetic field

There are various implementations of common fluids in industrial and chemical processes. With the cooperation of the nanoparticles, the lower thermal properties of such fluids can be augmented. By using a new kind of nanofluid namely hybrid nanofluid, the heat transfer rate of such fluids can be boosted more quickly. The main intention of this research is on entropy analysis in the stagnant point flow of a hybrid nanofluid. The mixed convection nonlinear thermal radiative flow on a stretchable vertical sheet is examined under the influences of the induced magnetic field and chemical reactions. The impacts of Joule heating, partial slips and viscous dissipation are also involved. After the execution of the appropriate similarity transformations, the constituting equations of the flow problem emerge as the nonlinear dimensionless setup of ordinary differential equations. An amplification is examined in the velocity field, entropy generation, and induced magnetic field relative to the mixed convection parameter. With the improved Brinkman number, an augmentation is developed in the entropy of the system. Moreover, both the heat transfer rate and the surface drag force exhibit an accelerating behavior relative to the mixed convection parameter.

Distributed dislocation problems in wedge shaped domains

We describe a method to tackle problems such as the presence of cracks or a region of partial slip, in wedge shaped domains, using distributed dislocations, alternatively considered as the edges of complete contacts. An asymptotic solution is sought, which is then applicable to many different contacts. Efficiencies are sought and described in comparison to previous approaches, both in terms of computational cost and kernel complexity. Three example problems, a crack, a slip zone, and a pair of cracks, are discussed.

Heat transfer aspects in Carreau nanofluid having hybrid nanoparticles through a porous medium

AbstractThe effects of nanofluid radiation and magnetic fields are important in biotechnology and medical treatment. The efficiency of hybrid nanomaterials flow (Carreau fluid) over a porous medium was investigated, and the findings were presented. The partial slip impact was used to thoroughly scrutinize the properties of the nanofluid flow. Using suitable variables, the PDEs in the Carreau model were reduced to ODEs, and the governing PDEs were transformed to ODEs using similarity transformations. The consequent ODEs are numerically investigated using the RKF‐45 Method. Furthermore, the results of the parameters involved in thermal and velocity were discussed. To the finest of the journalists' knowledge, no one has endeavored to depict medical occurrences and medical approaches by watching the flow through a malleable porous medium including blood as a base fluid and hybrid nanostructure materials. Indeed, the endeavors of this study are exceptional, and the obtained simulations have never been published by anyone academic.