Partial Slip Conditions Research Articles

Significance of heat transfer in a reversible esterification of Arrhenius activation energy with partial slip

The significance of heat transfer during a reversible esterification process in a magnetohydrodynamic boundary layer Casson fluid flow along a vertical stretching plate is examined. The multi-slip conditions are considered in a porous medium. The presence of chemical process requiring an activation energy is considered in the analysis. The study also investigates the hydromagnetic boundary layer Casson fluid flow alongwith partial slip conditions across a vertical stretching plate. The incorporation of multi-slip constraints in a porous medium, alongside magnetic fields and other parameters, highlights its relevance in diverse engineering fields such as thermal engineering, polymerization, and biodiesel industries. Understanding the characteristics of such fluids under complex conditions is vital for optimizing heat and mass transfer in industrial applications, making this investigation timely and valuable. The nonlinear differential set of equations are solved numerically involving Runge-Kutta based shooting approach of fourth order and the results are verified with the bvp4c tool and the findings are explored using graphical plots. The predominance of significant factors on flow configurations are analyzed and presented in graphs and tables. A comprehensive analysis is provided on the effects on velocity, concentration, and temperature of diverse parameters such as reaction rate constant, magnetic parameter, suction parameter, mass Grashof number, Prandtl number, Casson parameter, thermal radiation parameter and slip parameters. The tabular representation of the adverse effects of drag coefficient, rate of mass transfer and Nusselt number on flow configurations for various significant parameters is presented. It is inferred that for the case of reversible and irreversible flows, the shear stress rate escalates by 29% when the magnetic parameter elevates from 0.5 to 1.5 and about 35% when the Casson parameter elevates from 0.5 to 1.5. For the suction parameter, the coefficient of drag increased by 27% and 26% for irreversible and reversible flows respectively. When the reaction rate increases from 0.5 to 1.5, the rate of shear stress elevates by 0.5% and 0.02% for irreversible and reversible flows in order. The Nusselt number decreased about 7% and 8% when the magnetic parameter and Casson parameter rises from 0.5 to 1.5 respectively, for irreversible and reversible flows. It is noteworthy that the previous studies are in precise agreement with the present investigation.

Oscillations of coaxial hydrophobic spherical colloidal particles in a micropolar fluid

The microstructured flow field of a micropolar model around a straight chain of multiple hydrophobic spherical particles oscillating rectilinearly along their line of centers is studied under the conditions of low Reynolds numbers. In general, the particles can exhibit variations in both radius and amplitude of oscillations, and they are allowed to be unevenly spaced. The amplitudes are required to be small in comparison with a characteristic length, which can be considered as the radius of the larger particle. The concepts of slip length and spin slip length are introduced to characterize the partial slip and spin slip boundary conditions at the hydrophobic surfaces of the colloidal particles. The differential equations that govern the system are solved through a semi-analytical approach in combination with boundary collocation techniques. The interaction effects between the particles are assessed through the in-phase and out-of-phase drag force coefficients acting on each particle for various values of geometrical and physical parameters. The numerical schemes are carried for the case of two oscillating spherical particles. The results of this investigation indicate that the drag coefficients are notably influenced by the presence of the second particle, micropolarity, frequency, and slip parameters. The current study reveals that the impact of the micropolarity parameter is not significant on the in-phase force coefficient for slippage parameter values less than one. However, it becomes significant for slippage parameter values exceeding one. Typically, when particles oscillate in opposing modes, in-phase coefficient values surpass 1, whereas they fall below 1 when oscillating in the same mode. The present study is driven by the necessity to gain a deeper comprehension of the fluid tapping mode employed in atomic force microscope devices, especially when this mode pertains to microstructures in the vicinity of a curved surface.

Application of a hydrophobic coating to a pressurized pipe and its effect on energy losses and fluid flow profile

The use of additives, generally called DRAs (Drag Reducing Additives), has been proposed to re-duce the energy consumption in pressurized pipes. Although many research works have been conducted to analyze the effect of these additives, less attention have been devoted to the application of coatings to the pipe wall. This paper demonstrates that the application of a hydrophobic coating to the pipe can lead to a head loss reduction for a transition flow regime with moderate Reynolds number values (Re). For this purpose, an experiment was conducted to compare the performance of both coated and uncoated pipes by measuring the head losses and assessing the Drag Reduction Percentage (%DR) and the pipe friction factor (f). This was done for two Polyvinylchloride (PVC) pipes with different nominal diameters (PVC90 and PVC63). In addition, the flow velocity distribution was also measured in all these tests. The %DR decreased as the Re values increased, with the reduction being notably less pronounced for higher Re values. This could be explained by the fact that a partial slip condition is induced by the hydrophobic product. Its effect is significant for a transition regime where the effect of viscosity is important, but it becomes negligible for increasing levels of turbulence. No significant differences were observed in the flow distribution between coated and uncoated pipes, which seems to indicate that the velocity change could be limited to the near-wall viscous sublayer. The results of this work open an important research line aimed at reducing energy costs and the carbon footprint in pipe fluid distribution systems.

Analysis of Magnetohydrodynamic Free Convection in Micropolar Fluids over a Permeable Shrinking Sheet with Slip Boundary Conditions

The convective micropolar fluid flow over a permeable shrinking sheet in the presence of a heat source and thermal radiation with the magnetic field directed towards the sheet has been studied in this paper. The mathematical formulation considers the partial slip condition at the sheet, allowing a realistic representation of the fluid flow near the boundary. The governing equations for the flow, heat, and mass transfer are formulated using the conservation laws of mass, momentum, angular momentum, energy, and concentration. The resulting nonlinear partial differential equations are transformed into a system of ordinary differential equations using suitable similarity transformations. The numerical solutions are obtained using robust computational techniques to examine the influence of various parameters on the velocity, temperature, and concentration profiles. The impact of slip effects, micropolar fluid characteristics, and permeability parameters on the flow features and heat transfer rates are thoroughly analyzed. The findings of this investigation offer valuable insights into the behavior of micropolar fluids in free convection flows over permeable shrinking sheets with slip, providing a foundation for potential applications in various industrial and engineering processes. Key findings include the observation that the velocity profile overshoots for assisting flow with decreasing viscous force and rising magnetic effects as opposed to opposing flow. The thermal boundary layer thickness decreases due to buoyant force but shows increasing behavior with heat source parameters. The present result agrees with the earlier findings for specific parameter values in particular cases.

Parametric study for model calibration of a friction-damped turbine blade with multiple test data

Model updating using multiple test data is usually a challenging task for frictional structures. The difficulty arises from the limitations of nonlinear models which often overlook the uncertainties inherent in contact interfaces and in actual test conditions. In this paper, we present a parametric study for the model calibration process of a friction-damped turbine blade, addressing the experimentally measured response variability in computational simulations. On the experimental side, a recently developed test setup imitating a turbomachinery application with mid-span dampers is used. This setup allows measuring multiple responses and contact forces under nominally identical macroscale conditions. On the computational side, the same system is modeled in a commercial finite element software, and nonlinear vibration analyses are performed with a specifically developed in-house code. In numerical simulations, the multivalued nature of Coulomb’s law, which stems from the inherent variability range of static friction forces in permanently sticking contacts, is considered to be the main uncertainty. As the system undergoes vibration, this uncertainty propagates into the dynamic behavior, particularly under conditions of partial slip in contacts, thus resulting in response variability. A deterministic approach based on an optimization algorithm is pursued to predict the limits of the variability range. The model is iteratively calibrated to investigate the sensitivity of response limits to contact parameters and assembly misalignment. Through several iterations, we demonstrate how uncertain initial contact conditions can be numerically incorporated into dynamic analyses of friction-damped turbine blades. The results show a satisfactory level of accuracy between experiments and computational simulations. This work offers valuable insights for understanding what influences test rig response and provides practical solutions for numerical simulations to improve agreement with experimental results.

Instability analysis for MHD boundary layer flow of nanofluid over a rotating disk with anisotropic and isotropic roughness

The study focuses on the instability of local linear convective flow in an incompressible boundary layer caused by a rough rotating disk in a steady MHD flow of viscous nanofluid. Miklavčič and Wang's (Miklavčič and Wang, 2004) [9] MW roughness model are utilized in the presence of MHD of Cu-water nanofluid with enforcement of axial flows. This study will investigate the instability characteristics with the MHD boundary layer flow of nanofluid over a rotating disk and incorporate the effects of axial flow with anisotropic and isotropic surface roughness. The resulting ordinary differential equations (ODEs) are obtained by using von Kàrmàn (Kármán, 1921) [3] similarity transformation on partial differential equations (PDEs). Subsequently, numerical solutions are obtained using the shooting method, specifically the Runge-Kutta technique. Steady-flow profiles for MHD and volume fractions of nanoparticles are analyzed by the partial-slip conditions with surface roughness. Convective instability for stationary modes and neutral stability curves are also obtained and investigated by the formulation of linear stability equations with the MHD of nanofluid. Linear convective growth rates are utilized to analyze the stability of magnetic fields and nanoparticles and to confirm the outcomes of this analysis. Stationary disturbances are also considered in the energy analysis. The investigation indicates the correlation between instability modes Type I and Type II, in the presence of MHD, nanoparticles, and the growth rates of the critical Reynolds number. An integral energy equation enhances comprehension of the fundamental physical mechanisms. The factors contributing to convective instability in the system are clarified using this approach.

Cumulative fretting fatigue damage model for steel wire ropes

AbstractFretting fatigue contributes significantly to the fatigue failure process in steel wire ropes at the wire‐to‐wire trellis contact region with partial slip conditions. In this respect, this work demonstrates a new damage‐based fretting fatigue model for the prediction of such a failure process. The model is based on Lemaitre's damage equations for quasi‐brittle material with a damageable micro‐inclusion embedded in an elastic meso‐element. It incorporates the cyclic degradation of the elastic modulus of the drawn steel wire material. The fatigue life model acknowledges the mean stress effect. The constitutive and damage equations are formulated into user material (UMAT) subroutine for integration with Abaqus finite element analysis code. The localized fretting fatigue damage mechanism is simulated with an isolated two‐wire model. The effect of the contact condition with the coefficient of friction of 0.2 and 0.8 on the contact mechanics of the drawn wires is considered. The fretting fatigue mechanism map is established for each simulation case. The simulated results of N0 (no of cycles to initiate damage) and damage variable, D, confirm the fretting fatigue condition as the damage occurs in the slip region of the contact area for both the frictional conditions. The results were found in agreement with the previously establish Ruiz fretting parameter. This study will provide a base for the onward reliability assessment of steel wire ropes.

Vorticity dynamics at partial-slip boundaries

In this paper we discuss the dynamics of vorticity at partial-slip boundaries. We consider the total vector circulation, which includes both the total vorticity of the fluid and the slip velocity at the boundary (the interface vortex sheet). The generation of vector circulation is an inviscid process, which does not depend on either viscosity or the slip length at the boundary. Vector circulation is generated by the inviscid relative acceleration between the fluid and the solid, due to either tangential pressure gradients or tangential acceleration of the partial-slip wall. While the slip length does not affect the creation of vector circulation, it governs how vector circulation is distributed between the total vorticity of the fluid and the interface vortex sheet. Specifically, the partial-slip boundary condition prescribes the ratio between boundary vorticity and the strength of the interface vortex sheet, and the viscous boundary flux transfers vector circulation between the interface vortex sheet and the fluid interior to maintain this condition. The interaction between a vortex ring and a partial-slip wall is examined to highlight various aspects of this formulation. For the head-on collision, the quantity of vector circulation diffused into the fluid as secondary vorticity increases as the slip length is decreased, resulting in a stronger secondary vortex and increased rebound of the vortex ring. For the oblique interaction, the extent to which the vortex ring connects to the boundary increases as the slip length is increased.

A comparative study of several life prediction models based on the critical plane approach for fretting fatigue crack initiation

AbstractTo reasonably forecast the crack initiation characteristics of fretting fatigue, this study evaluates the accuracy of several damage models. The existing experimental and simulation investigations are compared, noting the similarities and differences in the crack initiation location, crack orientation angle, and crack initiation life predicted by various damage models. It is crucial to employ a reasonable and reasonable damage prediction model of fretting crack initiation life, as fretting fatigue, a phenomenon of mechanically fastened connecting parts, can considerably reduce the fretting fatigue life of the components. This paper compares the fatigue damage prediction models of fretting fatigue specimens under partial slip conditions, and it will help researchers understand the benefits and drawbacks of various damage models and give them the knowledge and foundation to select the more reasonable fretting fatigue damage model.

Моделирование гидродинамики, теплообмена и процесса усреднения гранулированных сред в пневматическом циркуляционном аппарате

The mathematical modeling of hydrodynamics, heat transfer, and averaging of a highly concentrated granular medium in the working area of a vertical pneumatic circulation apparatus is performed. The hydrodynamics of a dense layer of the granular medium is described by a non-Newtonian model with partial slip conditions on solid walls. Such a representation of the granular medium dynamics allows one to approve theoretical calculations with available experimental data for a steady flow in a flat channel. The numerical applicability of the partial slip condition for a non-Newtonian fluid is confirmed by the analytical dependences obtained by the authors for a steady flow in a circular tube and a flat channel, which are transformed into the known analytical formulas under no-slip conditions for a non-Newtonian medium. On the basis of the proposed model, the heat exchange intensity is analyzed when setting the constant heat flux density or the constant temperature on the annular shelves in the apparatus. The intensity of the granular mixture averaging in the bunker with the introduction of additional annular shelves is studied, and the efficiency of granular mixture mixing during rotation is considered. A method for analyzing the mixing of a granular medium in dynamics in each local area of the apparatus is proposed, which is based on the determination of the inhomogeneity coefficient. The results of this study can be used when developing powder technology devices for drying, mixing, dosing, and transport.

Theoretical study on thermal efficiencies of Sutterby ternary-hybrid nanofluids with surface catalyzed reactions over a bidirectional expanding surface

The key focus of this study is to explore the flow and heat transfer characteristics of a blood-based composite nanoparticles consisting of the Al2O3, SiC, and MWCNT on a Sutterby fluid over a bidirectional porous stretching surface. These ternary-hybrid nanomaterials (Al2O3, SiC, and MWCNT) exhibits remarkable thermal conductivity attributes and enhances heat transfer in fluids. In the presence of modified heat flux model and surface-catalyzed reactions, the investigation of heat and mass transfer is carried out. Further, the impact of velocity partial slip and thermal convective conditions are taken into description at the surface of the bidirectional expanding surface. The developed flow model is converted into set of couple nonlinear ODEs with suitable transformation and use the bvp4c approach on MATLAB to get the numerical solution. The analysis considers for ternary-nanoparticles (Al2O3+SiC + MWCNT) and unary (Al2O3) nanoparticles, and provides comprehensive description among both for various emerging parameters. The graphical finding shows that in the presence of Darcy-Forchheimer, the reduction is occurred in the fluid velocity significantly for tri-hybrid and unary nanofluid, also same trend is seen for the slip parameter.

A mathematical model-based investigation of liquid film dewetting over porous solid substrates

Thin liquid films resting on solid surfaces are susceptible to dewetting when physical inhomogeneities like surface roughness, textured patterns, and porosities are present on the substrate surface. These inhomogeneities affect liquid transport phenomena through dynamic wetting behavior and imbibition. They can render the liquid film unstable, thereby resulting in rupture and dewetting. Here, we mathematically model and simulate the dynamics of a thin liquid film with passive air above it, dewetting a porous solid substrate that bounds the liquid from below. The solid is modeled as a surface with regions of equally spaced pores, with a partial slip condition for the lateral velocity component of the liquid film, a spatially varying long-range attractive force parameter, as well as short-range repulsive interaction force parameters between the liquid–air interface and liquid–solid interface. Our results explain how the size and spacing of pore regions on the substrate, slip length of the liquid, and intermolecular force potentials influence the formation of morphological patterns and dewetting time scales of the liquid film.

Performance Optimization of a Multi-groove Water Lubricated Journal Bearing with Partial Slip by Taguchi Analysis

The importance of preserving the ecological balance has paved the way for developing water lubricated bearings for marine vessels and other various applications. These bearings have found widespread applications in high pressure water pumps, water-power plants and power generation stations in sea, mining industries, ships, boats and submarines. To investigate the performance envelope of a water lubricated journal bearing (WLJB) with partial slip/no slip pattern, a multi-groove bearing model is developed and analyzed using CFD in the present study. Taguchi analysis method is utilized to determine the highest influential parameter affecting the pressure distribution and load-carrying capacity of a water lubricated journal bearing. From Taguchi method, optimum values identified for design parameters such as attitude angle, groove angle, groove height and number of grooves are 60°, 9°, 7 mm and 2, respectively. For the optimum combination model, a higher load bearing capacity of 1484.5 N is attained. Approximately, 2.88 times increase in peak pressures are noted from the current optimal bearing model by comparing with previous findings. Results indicated that the number of grooves and groove angle are the most influential parameters affecting the bearing load capacity. Partial slip conditions are applied at the grooved surfaces of a bearing model designed based on the identified optimal groove parameters. Influence of varying slip intensity on bearing load capacity is analyzed using CFD simulation. Appropriate selection of slip regions and slip amplitude is found to play a major role influencing the performance of the water lubricated journal bearing.

Influence of Second-Order Partial Slip Conditions on Peristaltic Transport of MHD Pseudoplastic Fluid with Suction and Injection

Influence of Second-Order Partial Slip Conditions on Peristaltic Transport of MHD Pseudoplastic Fluid with Suction and Injection

Significance of Joule heating for radiative peristaltic flow of couple stress magnetic nanofluid

Nanofluids are gaining more importance in heat transfer applications because of their excellent thermal features, such as larger thermal conductivity, enhanced convective heat transfer coefficients, and better thermal stability. In a range of technical applications, including cooling structures, exchangers for heat, and thermal energy storage systems, they have the potential to increase the efficiency of heat transfer. Main aim is to address the peristalsis of couple-stress nanomaterial in a channel subject to partial slip conditions. Channel walls are compliant. Buongiorno model for thermophoresis and Brownian motion is accounted. Energy equation is modeled with considering the features of Ohmic heating and thermal radiation. The model is initially developed as a set of non-linear partial differential equations (PDEs). Using th appropriate similarity transformations, these are turned into a set of dimensionless ordinary differential equations (ODEs). The governing system of ODEs is solved by using numerical technique NDsolve. Detailed analysis for concentration, temperature, velocity, heat transfer rate, pressure gradient, skin friction coefficient, Sherwood and Nusselt numbers are analyzed. Reduction of problems with small Reynolds number and large wavelength is made. Concentration and velocity have reverse trends for higher couple stress fluid parameter. In addition, the radiation and Hartman number behave in an opposite sense for temperature. Rate of heat transfer is significantly accelerated by nanoparticles. Further, Nusselt number increases enhances via Brinkman number.

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.

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.

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

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.

Unification: Viscosity, permittivity, and hydration forces near an interface

In water-based solutions near interfaces, the hydration forces, dielectric permittivity, and viscosity depend on the short-range order in the arrangement of water molecules. The former two quantities were earlier rationalized by employing the Ginzburg–Landau expression for the solution free energy. Driven by the spirit of unification, we show that the dependence of the viscosity coefficient on the coordinate perpendicular to the interface can be rationalized in this framework as well by using in addition a linear Evans–Polanyi correlation between the activation energy determining viscosity and the solution free energy. In the conventional hydrodynamics, this effect is often formally described by introducing the partial-slip boundary conditions or a stagnant layer near interfaces. We show how the corresponding slip or stagnant-layer length can be explained and quantified.