Influence Of Wall Properties Research Articles

The influence of wall properties on convective heat transfer in isothermal nanochannel

The effect of solid wall properties on the convective heat transfer characteristic in a three-dimensional nanochannel is probed with molecular dynamics simulation. The interfacial velocity slip and temperature jump are treated as the function of the interatomic interaction, the atomic mass and thickness, respectively. The result shows that the wall properties, including interatomic interaction among wall atoms, atomic mass, as well as coating thickness based on certain interatomic interaction and atomic mass, will lead to significant changes in the temperature jump. These effects are caused by the variations of coupling degree of solid-liquid vibration frequency induced by the mismatch between solid wall and fluid atoms. Furthermore, temperature jump is also related to the solid-liquid interaction while the velocity slip is only related to the solid-liquid interaction. It's found that both the decrease of interatomic interaction and the increase of atomic mass can further enhance the heat transfer. That is, the interatomic interaction among wall atoms is closer to that among fluid atoms, the atomic mass of wall atoms is much greater than that of the fluid atoms, and the convective heat transfer in the channel is better. However, the variation of Nusselt number with coating thickness is notably, which exhibits a peak value in the hydrophilic and hydrophobic cases. It's indicated that vibrational density of states (VDOS) corresponding to a selected coating wall properties (including interatomic interaction, atomic mass and thickness) lies in between the VDOS of the channel wall atoms and that of fluid atoms, can play a role of thermal bridge between wall and fluid atoms and lead to a remarkable increase of heat transfer. Based on the selected solid wall properties, a reasonable selection of wall-fluid interaction can effectively increase velocity slip and achieve drag reduction.

Simultaneous Chemical Reactions Effect on Dispersion of a Solute in Peristaltic Propulsion of a Newtonian Fluid in an Inclined Channel with Wall Properties

In this paper, the dispersion of a solute in the peristaltic propulsion of an incompressible and viscous fluid through a permeable medium under the influence of wall properties with simultaneous homogeneous, heterogeneous chemical reactions in an inclined uniform channel has been studied. The issue is studied through conditions of Taylor’s limit and long wavelength hypothesis. The mean effective coefficient of scattering expression is computed and outcomes are interpreted physically through graphs.

Influence of Wall Properties on the Peristaltic Flow of a Jeffrey Fluid in a Uniform Porous Channel under Heat Transfer

Incompressible Jeffrey fluid under peristalsis is considered into permeable conduit. Magnetic effect and slip effect are studied for this channel in the existence of wall slip and heat transfer. Time average velocity, heat transfer coefficient and temperature are obtained analytically underneath the presumption of large wavelength approximation and also small Reynolds number. Effects of magnetic number, slip parameter, elasticity parameters and Brinkman number on coefficient of heat transfer and temperature field are graphically discussed. It is observed that in the case of temperature distribution the flow intensity enhances with rise in the Darcy number, while it reduces with enhancement in the Brinkman number and slip parameter.

The Study of Peristaltic Motion of Third Grade Fluid under the Effects of Hall Current and Heat Transfer

Abstract This article is concerned with the peristaltic pumping of an incompressible, electrically conducting third grade fluid in a uniform channel. The Hall effect under the influence of wall properties and heat transfer is taken into account. Mathematical modelling is based upon continuity, momentum, and energy equations. Closed form solutions for velocity, temperature, concentration, and heat transfer coefficient are obtained. Effects of pertinent parameters, such as third grade parameter Γ, Hall parameter M, amplitude ratio ε, Brickman number Br, Soret number Sc, wall tension E 1 and elasticity parameters E 2 and E 3 on the velocity u, temperature θ, concentration φ, and heat transfer coefficient Z, are discussed through graphs.

Peristaltic motion of Johnson-Segalman fluid in a curved channel with slip conditions.

Slip effects on the peristaltic transport of Johnson-Segalman fluid through a curved channel have been addressed. The influence of wall properties is also analyzed. Long wavelength and low Reynolds number assumptions have been utilized in the mathematical formulation of the problem. The equations so formed have been solved numerically by shooting method through computational software Mathematica 8. In addition the analytic solution for small Weissenberg number (elastic parameter) is computed through a regular perturbation method. An excellent agreement is noticed between the two solutions. The results indicate an increase in the magnitude of velocity with an intensification in the slip effect. Moreover the size and circulation of the trapped boluses increase with an increase in the slip parameter. Unlike the planar channel, the profiles of axial velocity are not symmetric about the central line of the channel.

Influence of Wall Properties on the Peristaltic Flow of a Nanofluid in View of the Exact Solutions: Comparisons with Homotopy Analysis Method

No doubt, the exact solution of any physical system is considered optimal when it is available. Such exact solution is of great importance not only in validating the accuracy of the approximate solution obtained for the same problem but also to derive the correct physical interpretation of the involved physical phenomena. In this paper, the system of linear and nonlinear partial differential equations describing the peristaltic flow of a nanofluid in a channel with compliant walls has been solved exactly. These exact solutions have been implemented to explore the exact effects of Prandtl number Pr, thermophoresis parameter NT, Brownian motion parameter NB, and Eckert number Ec on the temperature, the nanoparticle concentration profiles, and the heat transfer coefficient Z(x). In addition, the exact results have been compared with a very recent work via the homotopy analysis method for the same problem. Although these comparisons showed that the published approximate results coincide with the current exact analysis, a few remarkable differences have been detected for the behaviour of the heat transfer coefficient.

Influence of wall properties on the peristaltic flow of a nanofluid: Analytic and numerical solutions

This study is concerned with the peristaltic transport of nanofluid in a channel with complaint walls. Transport equations involve the combined effects of Brownian motion and thermophoretic diffusion of nanoparticles. Mathematical modeling is carried out by utilizing long wavelength and low Reynolds number assumptions. The coupled nonlinear boundary value problem (BVP) has been solved numerically by using shooting technique through software Mathematica. The analytic solutions are computed by a robust analytical tool namely the homotopy analysis method (HAM). Attention has been focused on the behaviors of Brownian motion parameter (Nb), thermophoresis parameter (Nt), Prandtl number (Pr) and Eckert number (Ec). The results indicate an appreciable increase in the temperature and nanoparticles concentration with the increase in the strength of Brownian motion effects. Further heat transfer coefficient is a decreasing function of Nb and Nt.

Influence of wall properties on peristaltic transport of second grade fluid with heat and mass transfer

AbstractThis paper discusses the effects of heat and mass transfer on the magnetohydrodynamic (MHD) peristaltic flow of second grade fluid in a channel with flexible walls. Expressions of stream function, temperature, concentration field, and heat transfer coefficient have been computed. The effects of sundry parameters are sketched and examined. The known results of viscous fluid are obtained as the limiting cases of the present expressions. © 2011 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library (wileyonlinelibrary.com/journal/htj). DOI 10.1002/htj.20361

The influence of wall properties on the MHD peristaltic flow of a Maxwell fluid with heat and mass transfer

This article describes the effects of heat and mass transfer on the magnetohydrodynamic (MHD) peristaltic flow in a planar channel with compliant walls. An incompressible Maxwell fluid occupies a porous space. The mathematical formulation is based upon the modified Darcy’s law. The analytic treatment of the solution is given by choosing a small wave number. The expressions of stream function, temperature distribution, concentration field and heat coefficient are constructed. The variations of several interesting parameters are discussed by sketching plots.

On the influence of wall properties in the MHD peristaltic transport with heat transfer and porous medium

The effect of elasticity of the flexible walls on the MHD peristaltic flow of a Newtonian fluid in a two-dimensional porous channel with heat transfer has been studied under the assumptions of long-wavelength and low-Reynolds number. The analytical solution has been obtained for the stream function, temperature and heat transfer coefficient. The effect of various emerging parameters on the flow characteristics are shown and discussed with the help of graphs. The numerical results show that the trapped bolus increases in size and more trapped bolus appears with increasing permeability parameter, elastic tension and mass characterizing parameters but decreases for large values of Hartmann number.

Influence of wall properties on peristaltic transport with heat transfer

The effect of elasticity of the flexible walls on peristaltic transport of an incompressible viscous fluid, with heat transfer, in a two dimensional uniform channel has been investigated under long wave length approximation. The perturbation solution has been obtained in terms of wall slope parameter and closed form expressions have been derived for velocity, temperature and heat transfer. The effects of elastic tension, damping and mass characterizing parameters on temperature and heat transfer have been studied. It is found that heat transfer increases with elastic tension and mass characterizing parameters. To cite this article: G. Radhakrishnamacharya, Ch. Srinivasulu, C. R. Mecanique 335 (2007).

Influence of Wall Properties on Perstalsis in the Presence of Magnetic Field

Influence of Wall Properties on Perstalsis in the Presence of Magnetic Field

Influence of wall properties on the morphological change of Sb 2O 3 fine particles induced by impaction against a wall

The influence of wall properties on the morphological change of fine particles induced by impact against a wall was investigated using antimony trioxide (Sb 2O 3) fine particles and four kinds of impaction plates (copper, borosilicate glass, polyacetal resin and polyurethane resin). It was found that the change of median diameter through the impact was dependent on the elastic properties of the impaction plates. Estimation of the maximum impaction load based on the theory of elasticity revealed that the threshold of the load causing the particle enlargement took the same values among the four kinds of impaction plates. It was also found that die change of particle size distribution was described by three components of the distributions: crushed particles, non-crushed particles and granulated particles. The difference in the change of these three components was well explained by the elastic and adhesive properties of the walls.

Influence of wall properties on Hartmann flow and heat transfer in a rotating system

The influence of rotation and physical properties of bounding walls on a generalized one-dimensional Hartmann flow (HF) and heat transfer is investigated. The channel rotates with a constant angular velocity about an axis perpendicular to the walls in a uniform transverse magnetic field. Exact solutions for the velocity, magnetic field, viscous stress, current density, temperature distribution, yield components, net electric current components, mean temperature as well as Nusselt numbers are derived. Effects of relevant parameters such as rotation parameter, Hartmann, Eckert and Prandtl numbers, wall conductivities, wall thicknesses are examined numerically and shown graphically.

On the influence of wall properties and Poiseuille flow in peristalsis

The present study extends the two-dimensional analysis of peristaltic motion by Fung and Yih to include an elastic or viscoelastic wall, and a Poiseuille flow. This fluid-solid interaction problem is investigated by considering equations of motion of both the fluid and the deformable boundaries. The wall characteristics appear in their equations of motion, which are solved to represent boundary conditions of fluid motion. The influence of Poiseuille flow on pure peristalisis is also investigated. The phenomenon of the ‘mean flow reversal’ is found to exist both at the center and at the boundaries of the channel. When the walls of the channel are elastic, pure peristalsis involves flow reversal only at the center. This position may shift drastically to the boundaries, if viscous damping forces are considered.