Slip Effects Research Articles

The potential role of retinal slip in National Football League (NFL) officiating and its effect on on-field decision making: mechanisms and countermeasures.

Visual processing involves numerous neuro-ophthalmic pathways that enable humans to perceive and interact with the world. These visual pathways can negatively impact visual perception and decision-making. The Vestibulo-Ocular Reflex (VOR) is a compensatory mechanism that stabilizes gaze on a target during head movement, such as running or turning. However, inadequate VOR stabilization can lead to retinal slip, reducing visual acuity. In the National Football League (NFL), officials require exceptional visual training and performance. NFL officiating utilize rapid visual processing, strategic movements, and precise judgement to make accurate penalty calls in real-time. Retinal slip can adversely affect play calling and penalty assessment by NFL officials. Despite these challenges, NFL officials achieve high precision and accuracy in up to 98.9% of plays. To maintain such high standards, the NFL has implemented a standardized curriculum to mitigate the effects of VOR and retinal slip. This manuscript outlines the basics of VOR function and explores countermeasures to minimize retinal slip in NFL officiating. We believe that these scientific endeavours can improve both penalty assessment accuracy and precision. The use of these general principles might also be potentially applicable to other sports.

Slippage flow of second-grade fluid over a vertical plate with thermo-diffusion effect: an application of hybrid fractional operator

This research investigates the effects of slip and thermo-diffusion on magnetohydrodynamic fluid flow and heat transfer through a porous medium, using a fractional second-grade fluid model. A semi-analytical solution is obtained through Laplace transform techniques, revealing detailed insights into concentration, temperature, and velocity distributions. The study sheds light on the significant impact of key parameters, including Prandtl and Schmidt numbers, Grashof numbers, and the second-grade parameter, on the intricate relationships between thermo-diffusion, slip conditions, and fluid flow in porous media.

Molecular Dynamics Simulation on Slippage Effect and Injection Capacity With Hydrophobic Nanoparticles Adsorption

ABSTRACTWith the continuous exploitation of global oil and gas resources, the focus of oilfield development has gradually shifted to low‐permeability and tight reservoirs. Nowadays the nanofluid has become one of the most important methods to enhance oil recovery in low‐permeability reservoir since the wettability and fluid flow characteristics can be changed as hydrophobic nanoparticles are adsorbed on the surface. In this study, we focus on the fluid slip characteristics feature of nanoparticles adsorbed with different adsorption degrees through molecular dynamics methods. Our results show that the adsorption of hydrophobic nanoparticles on the wall induces a velocity slip effect. The fluid flows in a Cassie state in the micro‐channel, with a significant increase in density, velocity, and slip length. In addition, the velocity in the mainstream area is significantly greater than that near the wall. The fluid flow rate within the pore channel is maximized and the most optimal adsorption degree is around 65.08%. Meanwhile, this study provides not only of great significance for the microscopic mechanism of pressure reduction and injection enhancement technology by nanoparticles adsorbed, but also an efficient method in enhance oil recovery in low‐permeability oil reservoirs.

Contour and regression insights into Casson–Williamson nanofluid flow with suction/injection, hall currents, and ion slip effects

Contour and regression insights into Casson–Williamson nanofluid flow with suction/injection, hall currents, and ion slip effects

Analysis of thermal significances of nanofluids in inclined magnetized flow with Joule heating source and slip effects

The growing need for effective thermal management systems in engineering applications will improve performance by using nanofluids. Nanofluids, which show enhanced thermal characteristics compared to typical fluids, offer an effective way for heat transmission processes in industries. This study is particularly useful for systems where traditional fluids are insufficient for improving thermal performance. Understanding the overall impacts of Joule heating, magnetic fields, and slip conditions would be beneficial in fields such as aircraft, microelectronics, and biomedical engineering.The thermal significances of nanofluids in an inclined magnetized flow are analyzed in this work, taking slip effects and the Joule heating source into account. The motivation behind the current research is to investigate the flow and heat transfer behavior of magnetohydrodynamic (MHD) nanofluid under the influence of Joule heating in the presence of slip conditions.Based on conservation laws and suitable boundary conditions, the governing formulas for mass, momentum, energy, and nanoparticle concentration are developed. In this thermal investigation, unsteady nanofluid flow in two dimensions via a nonlinear stretched configuration is studied numerically together with an example of a non-uniform heat source. Using similarity transformation, the governing partial differential equation for chemical radiation and slip effects parameters for hydromagnetic flow is transformed into a set of ordinary differential equation (ODE). To solve these equations, a numerical method is applied. This study found that the velocity, mass transfer, temperature, concentration, heat transfer, and skin friction coefficient are significantly influenced by the chemical reaction, radiation parameter, and velocity slip. A graphical representation of the parameters influencing the heat transfer and the velocity changes in calculation is observed.

Shear strengthening effects of core-filling method for hollow-core slabs considering relative slip

Core-filling method has been actively utilized to improve the shear capacity of hollow-core slabs (HCSs). However, when a high shear force is applied, slip may occur at the interface between HCS unit and core-filling concrete due to a poor bond condition, which can significantly reduce the shear strengthening effect of the core-filling method. Nevertheless, there has been no relevant research that quantitatively measured the slip between HCS unit and core-filling concrete and investigated its impact on the reduction of shear capacity. Therefore, in this study, shear tests were performed on a total of six HCS specimens reinforced with core-filling concrete, where the compressive strength of core-filling concrete and the number of filled cores were set as the key test variables. During shear testing, the slip between HCS unit and core-filling concrete was measured so that the effect of slip on the shear capacity was discussed in detail. In addition, the shear capacities of the specimens were evaluated based on the structural codes and the partial interaction shear capacity model (PISCM) proposed by the authors in previous research. The test and analysis results indicated that, as the compressive strength of core-filling concrete or the number of filled cores increased, the shear capacity of HCS tended to increase. However, when slip occurred at the interface of filled cores, the improvement of shear capacity was reduced, suggesting that the shear strengthening effect of the core-filling method cannot be fully expected unless the composite performance of the HCS unit and filled cores is secured.

A new accurate solution method for steady forced convection in an unbounded flow around a circular cylinder in continuum and slip regimes

A new accurate numerical solution method for steady forced convection in an unbounded bidimensional flow around a circular cylinder is presented, addressing both the no-slip and slip regimes for Reynolds numbers and Knudsen numbers within the range 0.01 ≤ Re ≤ 47 and 0 ≤ Kn ≤ 0.1. The challenge of singular behaviour in infinite domains, which degrades numerical precision, is effectively mitigated by our new approach, unlike previous methods that truncate the flow domain. This method provides complete and correct description of the flow near the cylinder and in the far field perfectly reproducing the asymptotic solutions at large distances. We also present a new effective analytical solution for Oseen flow with slip effects, accurately representing flow at low Reynolds numbers. The validity of our numerical solution is confirmed by extensive comparisons with analytical solutions and numerical and experimental data from the literature. Additionally, we derive a new accurate correlation formula for the Nusselt number in slip flow regimes, involving both scenarios with and without temperature jump. This formula is crucial for engineering applications, especially in constant temperature hot-wire anemometry, as it avoids the requirement to correct heat transfer measurements due to slip and temperature jump effects when using very small diameter wires.

Magnetohydrodynamics (MHD) flow of ternary nanofluid and heat transfer past a permeable cylinder with velocity slip

The increasing demand for energy-efficient and environmentally sustainable solutions has driven the exploration of ternary nanofluids for enhanced heat transfer applications. This numerical study investigates the magnetohydrodynamics (MHD) flow and heat transfer characteristics of a ternary hybrid nanofluid (copper-alumina-titania/water) over a shrinking/stretching cylinder, considering the effects of velocity slip, suction, and curvature parameters. The variable wall temperature is also included in the physical model. The model in PDEs is transformed into a simplified version of differential equations (ODEs) which can be solved using the bvp4c solver. Validation against previously published data confirms the accuracy of the model. Two solutions are possible if the shrinking surface is permeable (with suction effect) while only unique solution for the stretching case. Surprisingly, the copper-alumina-titania/water exhibits a lower heat transfer rate but higher skin friction as compared to the copper-alumina/water. Specifically, the heat transfer coefficient decreases by 5-10% when incorporating the titania nanoparticle, while an increase of 8-12% for the skin friction coefficient. Additionally, the velocity slip and curvature parameters accelerate the boundary layer separation, whereas increased suction delays this process. These findings provide insights into optimizing thermal management systems using ternary hybrid nanofluids, particularly under MHD effects.

Effect of boundary slips on thermal EHL in simple sliding finite line contact considering limiting shearing stress

Effect of boundary slips on thermal EHL in simple sliding finite line contact considering limiting shearing stress

Thermal radiation, Newtonian heating, Hall and ion slip effects on Unsteady MHD Rotating Convective flow of Casson fluid past an infinite smooth vertical porous surface

Thermal radiation, Newtonian heating, Hall and ion slip effects on Unsteady MHD Rotating Convective flow of Casson fluid past an infinite smooth vertical porous surface

Thermocapillary stability of a viscoelastic liquid film falling down above or below an inclined thick wall with slip

Background:Thin viscoelastic liquid films falling down walls have been investigated theoretically since many years ago due to their applications in coating and cooling of substrates. They may also be subjected to temperature gradients and have been investigated under a variety of boundary conditions. In particular, the Navier slip boundary condition has been the subject of recent research. This condition is used when at the interface between the liquid and the wall the no-slip boundary condition does not apply due to different reasons like wall small topography, chemical coatings, etc. Methods:The small wavenumber approximation is used to derive a nonlinear evolution equation to describe the free surface deformations of the viscoelastic liquid film falling down an inclined wall. This equation is linearized and its linear stability is investigated using normal modes. The nonlinear free surface deformations are calculated numerically by means of a normal modes expansion substituted into the nonlinear evolution equation. Significant Findings:The thermocapillary stability of a thin viscoelastic film falling down a thick wall of finite thermal conductivity is investigated. Linear and nonlinear flows are examined when the interface of the liquid and the wall presents slip effects. The stability of the flow above and below (Rayleigh–Taylor) the wall is also explored. The lubrication approximation is used to derive a nonlinear evolution equation for the free surface deformation. The curves of linear growth rate, maximum growth rate and critical Marangoni number are calculated for different viscoelastic Deborah numbers. The film will be subjected to destabilizing and stabilizing Marangoni numbers. It is found that from the point of view of the linear growth rate the flow destabilizes with slip in a wavenumber range k<k+. However slip stabilizes for larger wavenumbers k>k+ up to the critical (cutoff) wavenumber. The results show that the Deborah number displaces k+ to the right. When k+ reaches the critical wavenumber by an increase of the Deborah number, slip is unable to stabilize. The corresponding critical Deborah number is derived. On the contrary, when the Deborah number is zero these slip stabilizing regions k>k+ correspond to Newtonian fluids investigated in previous works. From the point of view of the maximum growth rate slip may stabilize or destabilize increasing the slip parameter depending on the magnitude of the Marangoni, Galilei and Deborah numbers. Explicit formulas were derived for the intersections where slip may change its stability properties. Numerical solutions of the free surface nonlinear evolution equation show that slip can decrease the amplitude and may stimulate the appearance of subharmonics. The effects of different wall properties are also investigated.

Numerical study of unsteady thin film flow of power-law tetra hybrid nanofluid with velocity slip effect over a stretching sheet using sodium alginate as base fluid

This study examines the influence of power-law nanofluid flow and velocity slip on the heat transfer performance of tetrahybrid nanofluids over a stretching sheet, with the objective of enhancing thermal efficiency in industrial applications. The tetrahybrid nanofluids, consisting of Al2O3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$Al_2O_3$$\\end{document}, TiO2\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$TiO_2$$\\end{document}, Cu, and Fe3O4\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$Fe_3O_4$$\\end{document} nanoparticles suspended in a sodium alginate base fluid, represent a novel combination of materials whose collective thermal properties have not been extensively studied. The performance of these tetrahybrid nanofluids is compared to that of hybrid and tri-hybrid nanofluids to evaluate their relative heat transfer capabilities. The boundary layer equations are solved using MATLAB’s bvp4c solver, applying similarity transformations to investigate temperature and velocity profiles under varying parameter conditions. The results indicate that tetrahybrid nanofluids significantly enhance heat transfer rates compared to standard nanofluids, with improvements of 7.43%, 6.27%, and 5.35% over hybrid and tri-hybrid nanofluids, respectively. Furthermore, the analysis reveals that velocity profiles intersect at a specific point, and as the velocity slip parameter increases, the profiles move further away from the stretching sheet. Key factors, such as the Prandtl number, power-law index, slip parameter, magnetic field, and Reynolds number, are also examined for their effects on flow and thermal behavior. The key innovation of this research lies in the introduction of tetrahybrid nanofluids as an advanced medium for heat transfer, providing superior thermal efficiency compared to previously studied nanofluids. This study not only builds upon existing research but also provides new computational insights into the potential applications of tetrahybrid nanofluids in areas like food processing and other industries requiring effective thermal management.

Elastic local buckling of double-skinned UHPC composite plates considering interfacial shear slip

This study explores the elastic local buckling behavior of double-skinned ultra-high-performance concrete (DS-UHPC) composite plates, focusing on the effects of interfacial shear slip. A theoretical model, based on the first-order shear deformation theory for sandwich plates, was developed to predict the elastic local buckling behavior of these composite plates. An analytical solution for the elastic buckling coefficient under uniform compression with a simply supported boundary condition was derived. The results reveal that interfacial shear stiffness and the proportion of cross-sectional steel content significantly affect the elastic buckling coefficient. Specifically, lower interfacial shear stiffness and higher steel content proportion result in a decreased buckling coefficient, while increasing interfacial shear stiffness reduces the sensitivity of the buckling coefficient to variations in steel content proportion. Finite element models were established and validated against previous studies on the buckling performance of single-layer steel-concrete composite plates and classical solutions of buckling coefficients without interfacial shear slip. Semi-analytical solutions for the elastic buckling coefficient under various boundary conditions were also developed through a comprehensive set of finite element results. Building on these findings, a design procedure for DS-UHPC composite plates is proposed, emphasizing the optimization of interfacial connectors to minimize shear slip effects on local buckling. This procedure ensures the prevention of local buckling in both the external steel plates and the entire composite plate, thereby enhancing structural stability.

Insight into thermal dynamic of stagnated flow of MHD Jeffery fluid when the joule heating, viscous dissipation and Soret effect are present: A multistep Milne's approach

The purpose of this work is to use the RK approach in conjunction with Milne's Predictor Corrector method to investigate the numerical solution of the magnetohydrodynamic Jeffery fluid passing over the upper horizontal parabolic surface. Milne's predictor-corrector methodology is highly important since it increases result accuracy when compared to either approach alone. The physical aspects are investigated by using the variable fluid properties, and consider the stagnation point and boundary layer flow of the MHD Jeffery fluid, which flows on the upper horizontal parabolic surface. The influence of Jeffery fluid flowing the paraboloid surface is ascertained by measuring the velocity slip and melting surface effects. We examined both the heat and mass transfer rates with the effects of viscous dissipation, Joule heating, heat source/sink, activation energy, and the Soret effect because these rates are important in chemical reactions, electronic devices, climate change, separation and distillation processes, and water and air pollution. The governing equations in the form of PDEs are obtained by implementing all of the assumptions on the fundamental conservation laws. These equations are then converted into ODEs by using the similarity variables. The "Milne's Predictor-Corrector Method" is a numerical strategy used to solve numerical problems and the results are analyzed both graphically and numerically manners with this numerical technique. Analysis is done on the graphical behavior of many parameters on the temperature, concentration, and velocity regions. The numerical findings of skin friction and Nusselt number are also presented here, and the outcomes are compared with the results of the BVP5c and Milne's (Predictor-Corrector) methods. The obtained results indicated that the motion (velocity) of Jeffery fluid is restricted by the enhancement in Deborah number, retardation to relaxation parameter, Hartmann number, and viscosity parameter, whereas augmentation happens in fluid velocity due to melting parameter and stretching ratio parameter. The temperature region can be increased by the source of the viscosity parameter, Hartmann number, heat source/sink parameters, and Eckert number. The decline in the concentration distribution is noted due to activation energy and the reaction rate parameter, while an upsurge in concentration occurs due to the Soret number.

Flow of viscous electron fluids over sphere

The transport of strongly interacting electrons in ultrapure crystals is usually considered as the movement of an electron fluid. The study of various physical phenomena associated with the flow of electrons in superconducting materials in many problems can be realized from the point of view of the movement of viscous fluids. The article presents an analytical solution to the problem of electron fluid flowing around a spherical obstacle in the case when electrons strongly interact with each other. Expressions for the profiles of the longitudinal and transverse velocity components were obtained for the first time. The influence of electron collision effects and slip effects on the vibrational characteristics of velocity profiles is analyzed. The impossibility of flow separation and the formation of a Karman vortex street in an e-fluid are shown.

Numerical investigation for bioconvection flow of radiative viscoelastic nanofluid with triple diffusion and higher-order slip effects in a porous medium

Owing to enhanced thermal features, the study of nanofluids has become motivating research area which include various applications in renewable energy, thermal management devices, heat exchangers, microelectronics cooling, automotive industry etc. Owing such applications in mind, the aim of current investigation is to present a triple diffusion flow of viscoelastic nanofluid in presence of higher order slip effects. The problem investigates the insight of thermo-diffusion phenomenon with visualization of heat transfer, solutal concentration, nanoparticles concentration and bioconvection applications. The radiative impact with nonlinear relations and heat source are incorporated in the heat equation. The numerical simulations of problem have been performed via shooting scheme. Various applications are claimed with variation of flow parameters. It has been observed that the increase of the slip parameter enhances both the temperature nanofluid and concentration profiles. The solutal concentration profile increases due to Dufour Lewis number. Moreover, the change in nano-Lewis number leads to a decrease of concentration profile.

Numerical Assessment of the Thermal Performance of Microchannels with Slip and Viscous Dissipation Effects.

Microchannels are widely used across various industries, including pharmaceuticals and biochemistry, automotive and aerospace, energy production, and many others, although they were originally developed for the computing and electronics sectors. The performance of microchannels is strongly affected by factors such as rarefaction and viscous dissipation. In the present paper, a numerical analysis of the performance of microchannels featuring rectangular, trapezoidal and double-trapezoidal cross-sections in the slip flow regime is presented. The fully developed laminar forced convection of a Newtonian fluid with constant properties is considered. The non-dimensional forms of governing equations are solved by setting slip velocity and uniform heat flux as boundary conditions. Model accuracy was established using the available scientific literature. The numerical results indicated that viscous dissipation effects led to a decrease in the average Nusselt number across all the microchannels examined in this study. The degree of reduction is influenced by the cross-section, aspect ratio and Knudsen number. The highest reductions in the average Nusselt number values were observed under continuum flow conditions for all the microchannels investigated.

Non-linear vibration analysis of hard rock TBMs with multiple state-dependent delays and stick–slip effects

Hard rock tunnel boring machines (TBMs) vibrate significantly during tunnelling, accelerating structural damage and cutter wear. The vibration mechanism and dynamic behaviours of TBMs are focused on in this study. A four degrees-of-freedom model that accounts for axial, torsional, pitch, and yaw vibrations that are coupled through the disc cutters–rock interaction is established. Then the state-dependent delay differential equations of motion of a TBM are derived. To determine the penetration in both normal cutting and cutter bounce states, the evolution of the cut surface profile for each cutter is governed by a partial differential equation that is then cast into a series of ordinary differential equations by using Galerkin projections. Numerical simulation shows that new unstable regimes appear due to cutterhead shimmy. Two instability mechanisms that are the cutterhead shimmy and the complete axial bounce, are revealed. It is found that multiple state-dependent delays, especially some of them associated with multiple regenerative effects, result in chaotic behaviours. The chaotic characteristics are in reasonable agreement with those observed from practical projects. The axial stick–slip effect works slightly in the cutterhead shimmy dominated regimes. However, it prevents complete axial bounce from occurring, and changes the predominant mechanism from the complete axial bounce to the cutterhead shimmy.

Biodegradable Poly (L-Lactic acid) Fibrous Membrane with Ribbon-Structured Fibers and Ultrafine Nanofibers Enhances Air Filtration Performance.

Here, the poly (l-lactic acid) (PLLA) membrane with multi-structured networks (MSN) is successfully prepared by electrospinning technology for the first time. It is composed of micron-sized ribbon-structured fibers and ultrafine nanofibers with a diameter of tens of nanometers, and they are connected to form the new network structure. Thanks to the special fiber morphology and structure, the interception and electrostatic adsorption ability for against atmospheric particulate matter (PM) are significantly enhanced, and the resistance to airflow is reduced due to the "slip effect" caused by ultrafine nanofibers. The PLLA MSN membrane shows excellent filtration performance with ultra-high filtration efficiency (>99.9% for PM2.5 and >99.5% for PM0.3) and ultra-low pressure drop (≈20Pa). It has demonstrated filtration performance that even exceeds current non-biodegradable polymer materials, laying the foundation for future applications of biodegradable PLLA in the field of air filtration. In addition, this new structure also provides a new idea for optimizing the performance of other polymer materials.

Loosening Phenomenon on Thin Plates Bolted Joint due to Offset Load

In this study, the new loosening behavior was discovered and investigated when offset loads were repeatedly applied to both ends of a bolted joint initially tightened to a thin plate made of high-tensile steel. In the experiments, the impact of offset distance on reduction of clamp force was investigated through multiple applications of symmetric offset axial load to the bolted joint assembly. The experimental results showed that even a slight offset load reduced the clamp force, and the larger the offset distance, the greater the reduction of the clamp force. It was also found that the decrease in clamp force depends not on the number of times the offset load is applied but on the magnitude of the offset load. Until now even if the thin plate bolted joint was subjected to an offset load, as long the plates do not deform significantly due to plastic deformation, it has been generally recognized that the clamp force is not reduced. This loosening phenomenon is new and its mechanism has not been elucidated yet. In order to clarify the mechanism that may lower the clamp force, this study conducted FE analysis using a simplified model of a bolted joint. In the FE model, the bolt and nut are considered as a single unit and the effect of slippage between the thread surfaces and the effect of plastic deformation is ignored by using elastic analysis. The results of the FE analysis showed that the main factor causing the reduction in clamp force was slippage between the thin plates to be joined, which was caused by offset load, and that the slippage didn't return to the original position resulting in the reduction in clamp force.