scispace - formally typeset
Search or ask a question

Showing papers on "Slip ratio published in 2016"


Journal ArticleDOI
TL;DR: In this article, the analysis of MHD flow and melting heat transfer of a nanofluid over a stretching surface taking into account a second-order slip model and thermal radiation was performed.
Abstract: The present paper is devoted to the analysis of MHD flow and melting heat transfer of a nanofluid over a stretching surface taking into account a second-order slip model and thermal radiation. Similarity solutions for the transformed governing equations are obtained. The reduced equations are solved numerically by applying a shooting technique using the Runge-Kutta Fehlberg method. The influences of the various involved parameters on velocity profiles, temperature profiles, concentration profiles as well as reduced skin friction coefficient, Nusselt number and Sherwood number are discussed through graphs and tables. These results show that the second-order slip flow model is necessary to predict the flow characteristics accurately in the presence of thermal radiation and melting effect.

277 citations


Journal ArticleDOI
TL;DR: In this article, the authors investigated the effect of partial slip on the velocity at the boundary, convective thermal boundary condition, Brownian and thermophoresis diffusion coefficients on the concentration boundary condition.
Abstract: In this paper we report on combined Dufour and Soret effects on the heat and mass transfer in a Casson nanofluid flow over an unsteady stretching sheet with thermal radiation and heat generation. The effects of partial slip on the velocity at the boundary, convective thermal boundary condition, Brownian and thermophoresis diffusion coefficients on the concentration boundary condition are investigated. The model equations are solved using the spectral relaxation method. The results indicate that the fluid flow, temperature and concentration profiles are significantly influenced by the fluid unsteadiness, the Casson parameter, magnetic parameter and the velocity slip. The effect of increasing the Casson parameter is to suppress the velocity and temperature growth. An increase in the Dufour parameter reduces the flow temperature, while an increase in the value of the Soret parameter causes increase in the concentration of the fluid. Again, increasing the velocity slip parameter reduces the velocity profile whereas increasing the heat generation parameter increases the temperature profile. A validation of the work is presented by comparing the current results with existing literature.

172 citations


Journal ArticleDOI
01 Jun 2016-Fuel
TL;DR: In this paper, a study of slip flow in shale gas reservoirs is presented, where the slip boundary conditions were used to obtain the slip coefficients and tangential momentum accommodation coefficient in porous media from the experimental data.

100 citations


Journal ArticleDOI
TL;DR: In this paper, a simulation of forced convection of FMWNT-water nano-fluid in a micro-channel under a magnetic field in slip flow regime is performed.
Abstract: Simulation of forced convection of FMWNT-water (functionalized multi-walled carbon nano-tubes) nano-fluid in a micro-channel under a magnetic field in slip flow regime is performed. The micro-channel wall is divided into two portions. The micro-channel entrance is insulated while the rest of length of the micro-channel has constant temperature ( T C ). Moreover, the micro-channel domain is exposed to a magnetic field with constant strength of B 0 . High temperature nano-fluid ( T H ) enters the micro-channel and exposed to its cold walls. Slip velocity boundary condition along the walls of the micro-channel is considered. Governing equations are numerically solved using FORTRAN computer code based on the SIMPLE algorithm. Results are presented as the velocity, temperature, and Nusselt number profiles. Greater Reynolds number, Hartmann number, and volume fraction related to more heat transfer rate; however, the effects of Ha and ϕ are more noteworthy at higher Re.

93 citations


Journal ArticleDOI
TL;DR: In this article, the impact of velocity slip on peristaltic flow through a porous medium with heat and mass transfer is investigated, and the relevant equations of flow with mass transfer have been developed.
Abstract: The present study concerned with the impact of velocity slip on MHD peristaltic flow through a porous medium with heat and mass transfer is investigated. The relevant equations of flow with heat and mass transfer have been developed. Analytic solution is carried out under long-wavelength and small Reynolds number approximations. The expressions for the stream function, temperature and concentration and the heat transfer coefficient are obtained. Numerical results are graphically discussed for various values of physical parameters of interest. The velocity and temperature field increase with an increase in the velocity slip parameter and permeability parameter while it decreases with an increase in the Hartmann number.

79 citations


Journal ArticleDOI
TL;DR: In this paper, an approximation of long wavelength and low Reynolds is used to model the governing equation of continuity and momentum equation for fluid phase and particulate phase for endoscopy and slip effects on blood flow of particulate fluid suspension induced by peristaltic wave through a non-uniform annulus.

75 citations


Journal ArticleDOI
TL;DR: In this article, a phenomenological model for the kinematics of flow near a superhydrophobic surface with periodic post-patterns at high Reynolds numbers is presented, which predicts an inverse square root scaling with solid fraction, and a cube root scaling of the slip length with pattern size, which is different from the reported scaling in the Stokes flow limit.
Abstract: Superhydrophobic surfaces can significantly reduce hydrodynamic skin drag by accommodating large slip velocity near the surface due to entrapment of air bubbles within their micro-scale roughness elements. While there are many Stokes flow solutions for flows near superhydrophobic surfaces that describe the relation between effective slip length and surface geometry, such relations are not fully known in the turbulent flow limit. In this work, we present a phenomenological model for the kinematics of flow near a superhydrophobic surface with periodic post-patterns at high Reynolds numbers. The model predicts an inverse square root scaling with solid fraction, and a cube root scaling of the slip length with pattern size, which is different from the reported scaling in the Stokes flow limit. A mixed model is then proposed that recovers both Stokes flow solution and the presented scaling, respectively, in the small and large texture size limits. This model is validated using direct numerical simulations of turbulent flows over superhydrophobic posts over a wide range of texture sizes from L+ ≈ 6 to 310 and solid fractions from ϕs = 1/9 to 1/64. Our report also embarks on the extension of friction laws of turbulent wall-bounded flows to superhydrophobic surfaces. To this end, we present a review of a simplified model for the mean velocity profile, which we call the shifted-turbulent boundary layer model, and address two previous shortcomings regarding the closure and accuracy of this model. Furthermore, we address the process of homogenization of the texture effect to an effective slip length by investigating correlations between slip velocity and shear over pattern-averaged data for streamwise and spanwise directions. For L+ of up to O(10), shear stress and slip velocity are perfectly correlated and well described by a homogenized slip length consistent with Stokes flow solutions. In contrast, in the limit of large L+, the pattern-averaged shear stress and slip velocity become uncorrelated and thus the homogenized boundary condition is unable to capture the bulk behavior of the patterned surface.

73 citations


Journal ArticleDOI
TL;DR: In this paper, the effects of magnetohydrodynamics and partial slip on blood flow of Ree-Eyring fluid through a porous medium have been investigated and the resulting equation is solved analytically and exact solution has been obtained.

71 citations


Journal ArticleDOI
TL;DR: In this article, the flow of magnetic nanofluid (ferrofluid) between two parallel rotating stretchable disks with different rotating and stretching velocities is addressed.

68 citations


Journal ArticleDOI
TL;DR: In this paper, the robust Casson model is implemented to simulate viscoplastic behavior of fluids and closed-form solutions are obtained under physiological limitations of low Reynolds number and large wavelength.

67 citations


Journal ArticleDOI
TL;DR: In this article, the authors proposed pressure drop measurements at low pressures to verify the slip flow effect by distinguishing the effects of filter inhomogeneity, and they found that the experimental dimensionless drag at low pressure conditions, which was obtained with correction by the inhomogeneous factor measured at atmospheric pressure, followed the theoretical prediction that includes slip flow correction (Kirsch and Stechkina, 1978) for both conventional PTFE and newly developed fluororesin nanofiber filter media.

Journal ArticleDOI
TL;DR: The hydrodynamic slip length was found to be channel-size independent using equilibrium calculations, i.e., suggesting a consistency with the definition of a surface property, for 5-nm channels and larger.
Abstract: Equilibrium and nonequilibrium molecular dynamics simulations were conducted in order to evaluate the hypothesis that the hydrodynamic slip length is a surface property. The system under investigation was water confined between two graphite layers to form nanochannels of different sizes (3-8 nm). The water-carbon interaction potential was calibrated by matching wettability experiments of graphitic-carbon surfaces free of airborne hydrocarbon contamination. Three equilibrium theories were used to calculate the hydrodynamic slip length. It was found that one of the recently reported equilibrium theories for the calculation of the slip length featured confinement effects, while the others resulted in calculations significantly hindered by the large margin of error observed between independent simulations. The hydrodynamic slip length was found to be channel-size independent using equilibrium calculations, i.e., suggesting a consistency with the definition of a surface property, for 5-nm channels and larger. The analysis of the individual trajectories of liquid particles revealed that the reason for observing confinement effects in 3-nm nanochannels is the high mobility of the bulk particles. Nonequilibrium calculations were not consistently affected by size but by noisiness in the smallest systems.

Journal ArticleDOI
TL;DR: In this paper, a numerical investigation of two dimensional steady state laminar boundary layer flow of a viscous electrically-conducting nanofluid in the vicinity of a stretching ∕ shrinking porous flat plate located in a Darcian porous medium is performed.
Abstract: A numerical investigation of two dimensional steady state laminar boundary layer flow of a viscous electrically-conducting nanofluid in the vicinity of a stretching ∕ shrinking porous flat plate located in a Darcian porous medium is performed. The nonlinear Rosseland radiation effect is taken into account. Velocity slip and thermal slip at the boundary as well as the newly developed zero mass flux boundary conditions are also implemented to achieve physically applicable results. The governing transport equations are reduced to a system of nonlinear ordinary differential equations using appropriate similarity transformations and these are then solved numerically using a variational finite element method (FEM). The influence of the governing parameters (Darcy number, magnetic field, velocity and thermal slip, temperature ratio, transpiration, Brownian motion, thermophoresis, Lewis number and Reynolds number) on the dimensionless velocity, temperature, nanoparticle volume fraction as well as on the skin friction, the heat transfer rates and the mass transfer rates are examined and illustrated in detail. The FEM code is validated with earlier studies for non-magnetic non-slip flow demonstrating close correlation. The present study is relevant to high-temperature nano-materials processing operations.

Journal ArticleDOI
TL;DR: In this article, the effects of various pertinent parameters on the axial velocity and temperature distributions are analyzed graphically and the skin friction and the Nusselt number are computed numerically and graphically.
Abstract: The present paper examines the hydromagnetic three-dimensional flow induced by a stretched surface. An incompressible material saturates the porous medium. Velocity and thermal slip boundary conditions are considered. Suitable transformations are used to obtain the nonlinear ordinary differential equations. Series solutions of the resulting systems are constructed. The effects of various pertinent parameters on the axial velocity and temperature distributions are analyzed graphically. The skin friction and the Nusselt number are computed numerically and graphically.

Journal ArticleDOI
TL;DR: In this article, the peristaltic transport of a couple stress fluid in an asymmetric and non-uniform channel under the action of an externally applied magnetic field was investigated.

Journal ArticleDOI
TL;DR: In this article, the impact of porosity medium on peristaltic flow in a curved channel is examined and the results reveal the activation of velocity and temperature with larger slip and Darcy number and reduction in nanoparticle volume fraction with advancement in slip effect.


Journal ArticleDOI
TL;DR: In this article, a numerical study of the effect of surface roughness on finite porous journal bearing with heterogeneous slip/no-slip surface is presented, where generalized Reynolds type equations are derived for both types of uni-dimensional roughness structure.

Journal ArticleDOI
TL;DR: In this article, the effect of surface charge and surface charge-dependent slip on the electroviscous effect and convective heat transfer of the pressure-driven flow in a micro tube was investigated.

Journal ArticleDOI
TL;DR: In this article, the peristaltic transport of Walters-B fluid in a compliant wall channel was studied in the presence of both velocity and thermal slip condition, and the solution expressions of stream function, velocity, temperature and heat transfer coefficient were derived.

Journal ArticleDOI
TL;DR: In this article, the authors examined the magneto-hydrodynamic (MHD) flow of nanofluid bounded by a stretching surface, and the involved differential systems are solved for the velocity, temperature and mass fraction.
Abstract: This article examines the magneto-hydrodynamic (MHD) flow of nanofluid bounded by a stretching surface. The slip conditions are utilized in the present analysis. The involved differential systems are solved for the velocity, temperature and mass fraction. Graphical and numerical results are reported for the analysis of various parameters of interest entering into the modeled problems. Combined effects of thermal and concentration jump are analyzed. Various tables are constructed to show the rheological effects of different physical parameters. Streamlines are plotted showing the rheology for the slip and no slip flow regime. Plots of skin friction are also prepared for the slip and magnetic field effects.

Journal ArticleDOI
TL;DR: In this paper, a mathematical model is presented for three-dimensional unsteady boundary layer slip flow of Newtonian nanofluids containing gyrotactic microorganisms over a stretching cylinder.
Abstract: A mathematical model is presented for three-dimensional unsteady boundary layer slip flow of Newtonian nanofluids containing gyrotactic microorganisms over a stretching cylinder. Both hydrodynamic and thermal slips are included. By applying suitable similarity transformations, the governing equations are transformed into a set of nonlinear ordinary differential equations with appropriate boundary conditions. The transformed nonlinear ordinary differential boundary value problem is then solved using the Runge-Kutta-Fehlberg fourth-fifth order numerical method in Maple 18 symbolic software. The effects of the controlling parameters on the dimensionless velocity, temperature, nanoparticle volume fractions and microorganism motile density functions have been illustrated graphically. Comparisons of the present paper with the existing published results indicate good agreement and supports the validity and the accuracy of our numerical computations. Increasing bioconvection Schmidt number is observed to depress motile micro-organism density function. Increasing thermal slip parameter leads to a decrease in temperature. Thermal slip also exerts a strong influence on nano-particle concentration. The flow is accelerated with positive unsteadiness parameter (accelerating cylinder) and temperature and micro-organism density function are also increased. However nano-particle concentration is reduced with positive unsteadiness parameter. Increasing hydrodynamic slip is observed to boost temperatures and micro-organism density whereas it decelerates the flow and reduces nano-particle concentrations. The study is relevant to nano-biopolymer manufacturing processes.

Journal ArticleDOI
TL;DR: In this paper, the effect of joule heating and velocity slip on MHD peristaltic flow in a porous medium with chemical reaction was investigated under long-wavelength and low-Reynolds number approximations.

Journal ArticleDOI
TL;DR: The results indicate that slip effects substantially influence the velocity and temperature distributions in the peristaltic transport of Powell-Eyring fluid inside a curved channel with complaint walls.

Journal ArticleDOI
TL;DR: In this paper, the effects of slip velocity on rotating electro-osmotic flow in a non-uniform micro-channel were studied and the non-linear Poisson-Boltzmann equation was solved numerically based upon which a Crank-Nicolson numerical scheme was developed for obtaining velocity distribution.

Journal ArticleDOI
15 Nov 2016-Energy
TL;DR: In this paper, an energy conversion under conduction, convection, diffusion and radiation was studied for MHD free convection heat transfer of a steady laminar boundary-layer flow past a moving permeable non-linearly extrusion stretching sheet.

Journal ArticleDOI
Chen Long1, Mingyuan Bian1, Yugong Luo1, Qin Zhaobo1, Keqiang Li1 
TL;DR: In this article, a resonance frequency-based tire-road friction coefficient (TRFC) estimation method is proposed by considering the dynamics performance of the in-wheel motor drive system under small slip ratio conditions.
Abstract: In this paper, a resonance frequency-based tire–road friction coefficient (TRFC) estimation method is proposed by considering the dynamics performance of the in-wheel motor drive system under small slip ratio conditions. A frequency response function (FRF) is deduced for the drive system that is composed of a dynamic tire model and a simplified motor model. A linear relationship between the squared system resonance frequency and the TFRC is described with the FRF. Furthermore, the resonance frequency is identified by the Auto-Regressive eXogenous model using the information of the motor torque and the wheel speed, and the TRFC is estimated thereafter by a recursive least squares filter with the identified resonance frequency. Finally, the effectiveness of the proposed approach is demonstrated through simulations and experimental tests on different road surfaces.

Journal ArticleDOI
TL;DR: A novel control method based on the modification of the famous super-twisting sliding mode algorithm is proposed, and rigorous mathematical analysis is given to guarantee the ultimate boundedness of the proposed algorithm.
Abstract: The friction between wheel and track is usually called adhesion force, and it is the critical factor for the movement of trains. On one hand, excessive driving force of a train may lead to insufficient utilization of the adhesion effect and cause wasted energy; on the other hand, insufficient driving force of a train brings inefficient train operation. To balance the issues of energy consumption, operational efficiency, and security, it is necessary to control a train to obtain its maximal adhesion force, particularly in the cases of fast acceleration and emergency braking. However, since engineering experiments indicate a complex nonlinear relationship between the adhesion force and the slip ratio of a train, such a control problem is difficult and challenging, particularly when the optimal slip ratio is unknown. Facing this problem, this paper proposes a novel control method based on the modification of the famous super-twisting sliding mode algorithm, and rigorous mathematical analysis is given to guarantee the ultimate boundedness of the proposed algorithm. Furthermore, by considering four different control scenarios, detailed control and estimation algorithms are both proposed. Simulation result verifies that the proposed control strategy can control the train to obtain its maximum adhesion force.

Journal ArticleDOI
TL;DR: In this article, the effects of anisotropic slip and thermal jump on the three dimensional stagnation point flow of nanofluid containing microorganisms from a moving surface have been investigated numerically.
Abstract: The effects of anisotropic slip and thermal jump on the three dimensional stagnation point flow of nanofluid containing microorganisms from a moving surface have been investigated numerically. Anisotropic slip takes place on geometrically striated surfaces and superhydrophobic strips. Zero mass flux of nanoparticles at the surface is applied to achieve practically applicable results. Using appropriate similarity transformations, the transport equations are reduced to a system of nonlinear ordinary differential equations with coupled boundary conditions. Numerical solutions are reported by means of very efficient numerical method provided by the symbolic code Maple. The influences of the emerging parameters on the dimensionless velocity, temperature, nanoparticle volumetric fraction, density of motile micro-organisms profiles, as well as the local skin friction coefficient, the local Nusselt number and the local density of the motile microorganisms are displayed graphically and illustrated in detail. The computations demonstrate that the skin friction along the x-axis is enhanced with the velocity slip parameter along the y axis. The converse response is observed for the dimensionless skin friction along the y-axis. The heat transfer rate is increased with greater velocity slip effects but depressed with the thermal slip parameter. The local Nusselt number is increased with Prandtl number and decreased with the thermophoresis parameter. The local density for motile microorganisms is enhanced with velocity slip parameters and depressed with the bioconvection Lewis number, thermophoresis and Peclet number. Numerical results are validated where possible with published results and excellent correlation is achieved.

Proceedings ArticleDOI
10 May 2016
TL;DR: In this paper, the theoretical and computational study of peristaltic hemodynamic flow of couple stress fluids through a porous medium under the influence of magnetic field with wall slip condition is discussed.
Abstract: In this paper, we discussed the theoretical and computational study of peristaltic hemodynamic flow of couple stress fluids through a porous medium under the influence of magnetic field with wall slip condition Actually this study is motivated towards the physiological flow of the blood in the micro circulatory system by taking account of the particle size effect We consider the Reynolds number is small enough and the wave length to diameter ratio is large enough to negate inertial effects The governing equations for the couple stress fluid flow through porous medium based on stoke constitutive equations and Brinkman model The exact solutions for axial velocity, pressure gradient, frictional force, stream function and mechanical efficiency are obtained analytically, its behaviour computationally discussed with reference to different physical parameters reflecting couple stress parameter, Hartmann number, permeability parameter, slip parameter as well as amplitude ratio on pumping characteristics and frictional force, stream lines pattern and trapping of peristaltic flow pattern are studied with particular emphasis making use of graphs