Effect Of Slip Boundary Condition Research Articles

Slip boundary conditions and through flow effects on double-diffusive convection in internally heated heterogeneous Brinkman porous media

A model for double-diffusive convection in a heterogeneous porous layer with a constant throughflow is explored, with penetrative convection being simulated via an internal heat source using the Brinkman model. In particular, we analyse the effect of slip boundary conditions on the stability of the model. Because of the many applications in micro-electro-mechanical systems (MEMS) and other microfluidic devices, a study of this problem is necessary. Both linear instability analysis and nonlinear stability analysis are employed. We accurately analyse when stability and instability will commence and determine the critical Rayleigh number as a function of the slip coefficient.

Transient electro-osmotic flow of generalized second-grade fluids under slip boundary conditions

This work investigates the transient slip flow of viscoelastic fluids in a slit micro-channel under the combined influences of electro-osmotic and pressure gradient forcings. We adopt the generalized second-grade fluid model with fractional derivative as the constitutive equation and the Navier linear slip model as the boundary conditions. The analytical solution for velocity distribution of the electro-osmotic flow is determined by employing the Debye–Hückel approximation and the integral transform methods. The corresponding expressions of classical Newtonian and second-grade fluids are obtained as the limiting cases of our general results. These solutions are presented as a sum of steady-state and transient parts. The combined effects of slip boundary conditions, fluid rheology, electro-osmotic, and pressure gradient forcings on the fluid velocity distribution are also discussed graphically in terms of the pertinent dimensionless parameters. By comparison with the two cases corresponding to the Newtonian fluid and the classical second-grade fluid, it is found that the fractional derivative parameter β has a significant effect on the fluid velocity distribution and the time when the fluid flow reaches the steady state. Additionally, the slip velocity at the wall increases in a noticeable manner the flow rate in an electro-osmotic flow.

Investigation into the effects of slip boundary condition on nanofluid flow in a double-layer microchannel

In this research, the laminar flow and heat transfer of kerosene/MWCNT nanofluid in a novel design of a double-layer microchannel under the influence of oscillating heat flux and slip boundary condition have been studied. This research has been investigated in the dimensionless lengths of (λ 1) 1/3, 2/3 and 3/3 and dimensionless slip velocity coefficients ranging from 0.001 to 0.1. The suspension of nanoparticles in kerosene as the base fluid has been studied in Reynolds numbers of 1–100 and volume fractions of 0–8%. The results indicate that, by using novel design of double-layer microchannel in λ 1 = 1/3, the maximum rate of performance evaluation criterion is obtained and by increasing the slip velocity coefficient, the amount of PEC becomes significant. Among the studied cases, in all Reynolds numbers and volume fractions, the dimensionless length of 1/3 has the maximum amount of friction coefficient. Also, by enhancing the volume fraction of nanoparticles, slip velocity coefficient, Reynolds number and significant reduction in thermal resistance of solid wall, Nusselt number enhances.

Entropy generation due to double diffusive convective flow of Casson fluids over nonlinearity stretching sheets with slip conditions

The present paper deals with the effects of slip boundary conditions and chemical reaction on the heat and mass transfer by mixed convective boundary layer flow of a non-Newtonian fluid over a nonlinear stretching sheet. The Casson fluid model is used to characterize the non-Newtonian fluid behavior. First order chemical reactions are considered. Similar solutions are used to convert the partial differential equations governing the problem to ordinary differential equations. The velocity, temperature and concentration profiles are obtained, numerically, using the MATLAB function bvp4c and those are used to compute the entropy generation number. The effect of increasing values of the Casson parameter is found to suppress the velocity field and temperature distribution. But the concentration is enhanced with the increasing of Casson parameter. The viscous dissipation, temperature and concentration irreversibility are determined and discussed in details.

Advanced Study of Unsteady Heat and Chemical Reaction with Ramped Wall and Slip Effect on a Viscous Fluid

This paper investigate the effect of slip boundary condition, thermal radiation, heat source, Dufour number, chemical reaction and viscous dissipation on heat and mass transfer of unsteady free convective MHD flow of a viscous fluid past through a vertical plate embedded in a porous media. Numerical results are obtained for solving the nonlinear governing momentum, energy and concentration equations with slip boundary condition, ramped wall temperature and ramped wall concentration on the surface of the vertical plate. The influence of emerging parameters on velocity, temperature and concentration fields are shown graphically.

Scale effect of slip boundary condition at solid\u2013liquid interface

Rapid advances in microelectromechanical systems have stimulated the development of compact devices, which require effective cooling technologies (e.g., microchannel cooling). However, the inconsistencies between experimental and classical theoretical predictions for the liquid flow in microchannel remain unclarified. Given the larger surface/volume ratio of microchannel, the surface effects increase as channel scale decreases. Here we show the scale effect of the boundary condition at the solid–liquid interface on single-phase convective heat transfer characteristics in microchannels. We demonstrate that the deviation from classical theory with a reduction in hydraulic diameters is due to the breakdown of the continuum solid–liquid boundary condition. The forced convective heat transfer characteristics of single-phase laminar flow in a parallel-plate microchannel are investigated. Using the theoretical Poiseuille and Nusselt numbers derived under the slip boundary condition at the solid–liquid interface, we estimate the slip length and thermal slip length at the interface.

Mixed Convection Boundary Layer Flow of Williamson Fluid with Slip Conditions Over a Stretching Cylinder by Using Keller Box Method

Abstract The aim of the present analysis is to examine the effects of slip boundary conditions and mixed convection flow of Williamson fluid over a stretching cylinder. The boundary layer partial differential equations are transformed into ordinary differential equations by using group theory transformations. The required ordinary differential equations are solved numerically by using implicit finite difference method known as Keller box method. The influence of dimensionless physical parameters on velocity and temperature profile as well as skin friction coefficient and local Nusselt number are presented graphically. Comparison has been made to the previous literature in order to check the accuracy of the method.

Computational study of 3D rarefied gas flow in microchannel with 90 bend

The pressure driven compressible gas flow through three-dimensional microchannel with 90° bend is numerically investigated using compressible viscous Navier–Stokes equations coupled with the first-order slip and Smoluchowski temperature jump boundary conditions. The results are compared to those from equivalent straight channel geometry in terms of mass flow rate and Poiseuille number. The competition between geometry, rarefaction and compressibility effects is discussed. The effect of slip boundary condition by comparison with no-slip results is estimated. The flow structure shows that 90° bend has in general a local effect and global performances are quite similar to those of a straight channel, allowing a certain freedom in the design of microdevices. However, it is found that the inclusion of a bend in a micro-channel produces a mass flow rate enhancement. Moreover, the pressure in bend is independent on an aspect ratio and behaves somewhat similar to two-dimensional microchannels, even for the square cross section. The velocity profile near the centerline is relatively similar along the width and depth for an aspect ratio of more than four, suggesting that the bent microduct can be modeled as a two-dimensional one, although, the velocity component along the depth is never identically zero, implying that the flow is not truly two dimensional.

Stoke's First Problem for Carbon Nanotubes Suspended Nanofluid Flow Under the Effect of Slip Boundary Condition

Stoke's First Problem for Carbon Nanotubes Suspended Nanofluid Flow Under the Effect of Slip Boundary Condition

Nonlinear vibration of coupled nano- and microstructures conveying fluid based on Timoshenko beam model under two-dimensional magnetic field

Nonlinear vibration response of coupled viscoelastic carbon nanotubes (CNTs) conveying viscous fluid is investigated based on nonlocal and modified couple stress theories. The CNTs are placed in a uniform two-dimensional (2D) magnetic field and modeled by a Timoshenko beam. The effect of slip boundary condition is considered in the Navier–Stokes relations based on the Knudsen number correction factor. The higher-order governing equations of motion are derived based on the energy method and Hamilton’s principle where the differential quadrature (DQ) approach is applied to obtain the nonlinear frequency of coupled system. A detailed parametric study is conducted, focusing on the combined effects of 2D magnetic field, Visco-Pasternak foundation, Knudsen number, surface effect, velocity of conveying viscous fluid, and different theories. Also, the Galerkin method is applied to compare our linear results to those that are obtained by the DQ approach. The results of this article could be useful in designing and manufacturing of double nano-/micromechanical systems that are usually used in advanced biomechanics and optics.

Flow-induced vibration of double bonded visco-CNTs under magnetic fields considering surface effect

Vibration of a double visco-elastic carbon nanotubes (CNTs) conveying viscous fluid coupled by visco-Pasternak medium is investigated based on visco-surface nonlocal theory. CNTs are placed in uniform longitudinal magnetic field and modeled by Euler–Bernoulli beam (EBB) theory. Visco-CNTs are conveying viscous fluid in which the effect of slip boundary condition is considered using Knudsen number correct factor in Navier–Stokes relations. The higher order governing equations of motion are derived based on Hamilton’s principle where differential quadrature (DQ) approach is applied to obtain the nonlocal frequency of coupled visco-CNTs system. The detailed parametric study is conducted, focusing on the combined effects of the magnetic field, visco-Pasternak foundation, Knudsen number, surface effect, aspect ratio, velocity of conveying viscous fluid and direct of fluid velocity. Also, it is found that trend of figures have good agreement with previous researches. The results of this work could be used in design and manufacturing of nano/micro mechanical system in advanced biomechanics applications with magnetic field as a parametric controller.

Effect of slip boundary conditions on the simulation of microparticle velocity fields in a conical fluidized bed

The hydrodynamic performance of micrometric TiO2 particles has been experimentally studied in a conical fluidized bed and the results compared with numerical simulations. Local solid velocities in the bed have been measured by means of an optical fiber technique under different operating conditions of particle loading and air velocity. The radial profiles of axial solid velocities have been simulated to assess the sensitivity of grid size, and different drag models, namely, those by Syamlal and O'Brien, Ahmadi and Ma, Arastoopour et al., and Gidaspow, for no‐slip, partial‐slip, and free‐slip boundary conditions (BCs). The different drag models record almost similar results, but those provided by the Gidaspow and Ahmadi–Ma models, together with free‐slip BCs, are in somewhat better agreement with the experimental data for conical fluidized beds with smooth walls. © 2013 American Institute of Chemical Engineers AIChE J, 59: 4502–4518, 2013

Instability in Poiseuille flow in a porous medium with slip boundary conditions

We study a model for Poiseuille flow instability in a porous medium of Brinkman type. In particular, we analyse the effect of slip boundary conditions on the onset of instability. Due to numerous applications in micro-electro-mechanical-systems and other microfluidic devices, such a study is essential. We accurately analyse as to when instability will commence and determine the critical Reynolds number as a function of the slip coefficient.

Effect of partial slip boundary condition on the flow and heat transfer of nanofluids past stretching sheet prescribed constant wall temperature

The objective of the present study is to analyze the development of the slip effects on the boundary layer flow and heat transfer over a stretching surface in the presence of nanoparticle fractions. In the modeling of nanofluid the dynamic effects including the Brownian motion and thermophoresis are taken into account. In the case of constant wall temperature a similarity solution is presented. The solution depends on a Prandtl number, slip factor, Brownian motion number, Lewis number, and thermophoresis number. The dependency of the local Nusselt and local Sherwood numbers on these five parameters is numerically investigated. To the best of author's knowledge, the effects of slip boundary condition in the presence of dynamic effects of nano particles have not been investigated yet. The results of the present paper show the flow velocity and the surface shear stress on the stretching sheet and also reduced Nusselt number and reduced Sherwood number are strongly influenced by the slip parameter.

SLIP EFFECT ON DIFFUSION OF CHEMICALLY REACTIVE SPECIES IN BOUNDARY LAYER FLOW OVER A VERTICAL STRETCHING SHEET WITH SUCTION OR BLOWING

In the present investigation, we study the effects of slip boundary condition on the diffusion of chemically reactive species in steady boundary layer flow of viscous incompressible fluid over a vertical stretching sheet with suction or blowing. The first-order chemical reaction is considered and wall concentration varies linearly along the sheet. The self-similar equations are obtained using similarity transformations and are solved numerically using shooting method. Our study reveals that due to the increase of diffusion parameter and blowing, the velocity increases, and it decreases with suction, Schmidt number, and reaction rate parameter. Importantly, for increase of slip parameter, the boundary layer thickness increases. In contrast, the concentration at a point increases only for increasing slip and blowing, while it decreases for increase of all other parameters.

Fluid Flow and Heat Transfer Within a Single Horizontal Fracture in an Enhanced Geothermal System

We present an analysis of fluid flow and heat transfer through a single horizontal channel with permeable walls which are at different temperatures. The problem is set in the context of hot dry rock geothermal energy extraction where water, introduced through an injection well, passes through a horizontal fracture by which transfer of heat is facilitated through advection of the fluid flowing toward the recovery well. We consider the walls of the fracture to have properties of a permeable medium and we study the effect of slip boundary conditions on velocity and temperature profiles for low Reynolds number (< 7) based on a similarity solution and perturbation expansion. We show that the velocity and heat transfer profiles are altered with the channel width, the permeability and a slip coefficient α, which is a dimensionless constant related to the inherent properties of the channel.

WITHDRAWN: A note on “Comment on effects of slip boundary condition on non-Newtonian flows in a channel [Commun. Nonlinear Sci. Numer. Simulat. 14 (2009) 1377–1384

This article has been withdrawn at the request of the author(s) and/or editor. The Publisher apologizes for any inconvenience this may cause. The full Elsevier Policy on Article Withdrawal can be found at http://www.elsevier.com/locate/withdrawalpolicy .

The Influence of Slippage on Trapping and Reflux Limits with Peristalsis through an Asymmetric Channel

The effects of slip boundary condition on peristaltic transport of incompressible Newtonian viscous fluid in an asymmetric channel is investigated, under the conditions of low Reynolds number and long wavelength. The pumping characteristics, trapping and reflux limits are studied for different values of the dimensionless slip parameterβ.

Effect of Slip Boundary Condition on the Design of Nanoparticle Focusing Lenses

The importance of nanoparticles as a building block for novel application has been emphasized in various fields. Especially, nanoparticle beam has been widely used to measure particle size distribution, synthesize materials, and generate micro-patterns, as it can enhance the measurement resolution and transport efficiency. The aerodynamic lens system has been developed to focus particles in a certain size range. The manufacturing of nanoparticles in gas phase is typically performed at the low pressure conditions and the design and simulation of lens at low pressure have been steadily reported. The computational fluid dynamics (CFD) has been utilized to analyze the flow field and obtain particle trajectories. However, previous work has used no-slip boundary condition at low pressure. This paper describes the lens design and simulation with slip boundary condition at low pressure (approximately 1 Torr). The design of lens is discussed on the basis of the Wang et al.'s guidelines and the commercial code FLUENT is used for simulation. The results of this study show that the difference of particle beam radius between no-slip and slip boundary conditions is 0.03 approximately 0.9 mm for particle size ranging from 3 to 200 nm with Brownian diffusion and that the transport efficiency is slightly higher with slip boundary condition.

Effect of Slip Boundary Condition on the Design of Nanoparticle Focusing Lenses

The importance of nanoparticles as a building block for novel application has been emphasized in various fields. Especially, nanoparticle beam has been widely used to measure particle size distribution, synthesize materials, and generate micro-patterns, as it can enhance the measurement resolution and transport efficiency. The aerodynamic lens system has been developed to focus particles in a certain size range. The manufacturing of nanoparticles in gas phase is typically performed at the low pressure conditions and the design and simulation of lens at low pressure have been steadily reported. The computational fluid dynamics (CFD) has been utilized to analyze the flow field and obtain particle trajectories. However, previous work has used no-slip boundary condition at low pressure. This paper describes the lens design and simulation with slip boundary condition at low pressure (∼1 Torr). The design of lens is discussed on the basis of the Wang et al.'s guidelines and the commercial code FLUENT is used for simulation. The results of this study show that the difference of particle beam radius between no-slip and slip boundary conditions is 0.03∼0.9 mm for particle size ranging from 3 to 200 nm with Brownian diffusion and that the transport efficiency is slightly higher with slip boundary condition.