Effects Of Variable Fluid Properties Research Articles

Numerical Analysis of the Mixed Flow of a Non-Newtonian Fluid over a Stretching Sheet with Thermal Radiation

A mathematical model is elaborated for the laminar flow of an Eyring-Powell fluid over a stretching sheet. The considered non-Newtonian fluid has Prandtl number larger than one. The effects of variable fluid properties and heat generation/absorption are also discussed. The balance equations for fluid flow are reduced to a set of ordinary differential equations through a similarity transformation and solved numerically using a Chebyshev spectral scheme. The effect of various parameters on the rate of heat transfer in the thermal boundary regime is investigated, i.e., thermal conductivity, the heat generation/absorption ratio and the mixed convection parameter. Good agreement appears to exist between theoretical predictions and the existing published results.

Effects of Variable Fluid Properties on Double Diffusive Mixed Convection with Chemical Reaction Over an Accelerating Surface

In this study, we investigate the effect of variable fluid properties such as variable viscosity, porosity, permeability, thermal conductivity, and solutal diffusivity on double-diffusive mixed convective flow over an accelerating surface under the influence of a higher-order chemical reaction. The governing equations of the physical problem involve a coupled nonlinear partial differential equations and which are transformed into a coupled nonlinear ordinary differential equations using a suitable similarity transformation. Numerical computation using shooting technique is adopted to study the physical characteristics of velocity, temperature and concentration for various values of non-dimensional parameters like Prandtl number, Eckert number, buoyancy parameters, viscosity parameter, porous parameter, a ratio of thermal conductivities, a ratio of solutal diffusivities and chemical reaction parameter etc are involved in the problem. The computed numerical results are presented in the graphs to illustrate the details of the flow characteristics and their dependence on physical parameters. Our computed results are compared with earlier works of Seddeek in the absence of a magnetic field and found in good agreement.

PHYSICAL EFFECTS OF VARIABLE FLUID PROPERTIES ON GASEOUS SLIP-FLOW THROUGH A MICRO-CHANNEL HEAT SINK

Physical effects induced in micro-convective gaseous slip-flow due to variation in fluid properties are numerically examined in this paper. The problem is particularly simulated for slip-flow through a micro-channel heat sink (MCHS) having constant heat flux supplied from the wall under hydrodynamically and thermally fully developed flow (FDF) conditions. It is observed that the Nusselt number (Nu) for slip-flow is significantly higher than the no-slip-flow condition and Nu is significantly affected due to variable fluid properties (VFP). Four different cases of VFP are studied in order to investigate their effects individually. Pressure and temperature dependent density (ρ(p, T)) variation flattens the axial velocity profile in radial direction (u(r)) profile which promotes faster-moving particles close to the wall which considerably enhances Nu. The incorporation of temperature-dependent viscosity (μ(T)) variation marginally enhances Nu along the flow. Incorporation of temperature-dependent thermal conductivity (k(T)) variation highly augments Nu due to higher ρ and higher k fluid near to the wall and the incorporation of temperature-dependent specific heat at constant pressure (Cp(T)) variation reduces Nu due to lower k fluid near to the wall. The investigation also shows that the pressure drop significantly deviates from no-slip to slip condition. Furthermore, the effects of VFP on the gauge static pressure drop (Δpg) and slip velocity are also examined. The incorporation of μ(T) and k(T) variations trivially affects the Δpg and slip velocity. However, the incorporation of Cp(T) variation significantly affects the Δpg and slip velocity.

Effect of Variable Fluid Properties and Magneto-Hydrodynamics for Convection with Couple Stress Fluid

An attempt is made for analyzing MHD mixed convection over a vertical heated plate with a couple of stress fluid numerically in a systematic manner. Unlike other research-based on literature surveys, the fluid properties are varied here where convection improves drastically compare to fixing them constantly. The boundary layer flow is estimated through mathematically formulated equations for the physical configuration considered. These formulated equations are very tedious to solve with specified boundary conditions in nature. Similarity transformations, RKF scheme, and NR method are used to convert those tedious non-linear PDE to higher-order ODE and hence to first order. Interpretation of various significant parameters is studied and observed their effects with momentum, energy, and solutal equations producing the fluid flow with the plotted graphs. The contribution of the Magnetic field is observed in velocity by reducing the force of the fluid flow. This work's main contribution is to see the effective convection with significant fluid flow parameters, with the inclusion variable fluid properties. Nu and Sh numbers are also computed. Certain added effects making them void are well suited and matched with researchers' previous works with a better agreement.

Effects of Variable Fluid Properties on Oblique Stagnation Point Flow of a Casson Nanofluid with Convective Boundary Conditions

Oblique stagnation point flow of a Casson nanofluid over a heated stretching surface is examined under the influence of variable fluid properties. The impact of variable fluid properties on the flow field is examined by taking a convective boundary condition into account. Momentum, energy and concentration equations are transformed into the non-linear ordinary differential system through suitable similarity transformations and are solved analytically via Optimal Homotopy Analysis Method (OHAM). Effect of pertinent parameters on dimensionless velocity, temperature and concentration are depicted graphically. Numerical values of skin friction, Nusselt number and Sherwood number have been calculated for various parameters. The results indicate that the axial velocity decreases with an increase in variable viscosity whereas the dual impact of variable viscosity is observed on transverse velocity.

Heat transfer characteristics of water flowing through micro-tube heat exchanger with variable fluid properties

The heat transfer characteristics of laminar single-phase forced convective water flow through a micro-tube heat exchanger are numerically investigated in this paper. Two-dimensional simulations are performed to find the effects of variable fluid properties on heat transfer for hydrodynamically and thermally developed flow. The effects of variable fluid properties on convective heat transfer coefficient (h) and Nusselt number (Nu) are significant for micro-convective flow. It is noted that the variation in temperature-dependent thermal conductivity [k(T)] greatly enhances the h as compared to the variation in temperature-dependent viscosity [µ(T)], although water viscosity–temperature sensitivity (SμT) is greater than that of thermal conductivity–temperature sensitivity (SkT). The effects of variation in wall heat flux (\(q_{\text{w}}^{\prime\prime}\)) and inlet temperature on heat transfer are investigated for variable fluid properties. It is noted that the Nu declines with an augment in \(q_{\text{w}}^{\prime\prime}\) for temperature-dependent density variation [ρ(T)]. The Nu increases with an increase in \(q_{\text{w}}^{\prime\prime}\) for µ(T) and k(T) variations. The results show that the Nu decreases with an increase in inlet temperature for variable fluid properties. The undevelopment and redevelopment of the flow are observed due to µ(T) variation. Additionally, the effects of wall heat flux, inlet temperature and inlet velocity on the variation of Nu/Pr1/3 with Re are examined for µ(T) variation.

Unsteady MHD Flow of Nanofluid with Variable Properties over a Stretching Sheet in the Presence of Thermal Radiation and Chemical Reaction

The unsteady magnetohydrodynamics (MHD) flow of nanofluid with variable fluid properties over an inclined stretching sheet in the presence of thermal radiation and chemical reaction is studied taking into account the effect of variable fluid properties in thermal conductivity and diffusion coefficient. The governing partial differential equations are transformed into ordinary differential equations by using similarity transformation. The numerical solutions of the problem are obtained by using the fourth order Runge-Kutta method in line with the shooting technique. It is found that the increase in both thermal conductivity and radiative heat flux decreases the heat transfer rate but increases the skin friction and mass transfer rates. It is further observed that the increase in porosity parameter and magnetic field reduces the skin friction, heat, and mass transfer rates.

Effect of variable fluid properties on the hydrodynamic and thermal characteristics of parallel flow microchannel heat exchanger

In this paper the parallel flow microchannel heat exchanger is numerically investigate and the effect of treating the properties of fluids as variables with temperature compared with constant fluid properties assumption on its performance is studied. A numerical simulation is made to solve 3D Navier stock equations in two fluids with temperature dependent properties and 3D energy equation in two fluids and solid walls taking into account the effect of entrance region and axial conduction in the walls. The properties entered to the main program by relations as a function of temperature using subroutines written to calculate the properties at the end of each iteration. The results obtained show that, treating the properties as a temperature dependent gives higher overall performance since it leads to obtain lower pressure drop and higher effectiveness compared with constant properties assumption.

Effect of Variable Fluid Properties on Magnetohydrodynamic Flow of Nanofluid Past a Flat Plate

Effect of Variable Fluid Properties on Magnetohydrodynamic Flow of Nanofluid Past a Flat Plate

Effect of Variable Fluid Properties on MHD Mixed Convection Flow of Second-Grade Fluid Over a Linear Heated Stretching Sheet with a Convective Boundary Condition

An analysis has been carried out to study the effect of variable fluid properties on MHD mixed convection flow of second-grade fluid flowing along an infinite stretching sheet with convective boundary condition. The fluid is placed on an infinite heated elastic surface with linear stretching rate and a vertical velocity component due to suction at the sheet is considered. The combined effects of inertia, viscous, visco-elastic, and magnetic forces are analyzed. The basic equations governing the flow, heat transfer, and mass transfer are reduced to a set of nonlinear ordinary differential equations by using appropriate similarity transformations for velocity, temperature, and concentration. The fluid viscosity is assumed to vary as an inverse linear function of temperature, whereas the thermal conductivity as a linear function of temperature. These equations are solved numerically and the results for velocity, temperature, concentration, skin friction, local Nusselt number, and local Sherwood number are discussed using flow parameters. The investigation reveals that Joule heating and viscous dissipation enhance the temperature profile, and there are considerable effects in the presence of variable fluid properties. Comparison with previous studies shows good agreement as a special case of the problem.

Effects of Variable Fluid Properties on MHD Non-Darcy Convective Flow from Vertical Plate with Heat Generation and Chemical Reaction

A numerical computation has been carried out to study, MHD flow of an electrically conducting viscous fluid from a semi-infinite vertical plate in a porous medium in the presence of heat source and homogeneous first order chemical reaction. The fluid and porous properties, thermal and solutal diffusivity, permeability and porosity are considered to be varied. The governing non-linear partial differential equations for the fluid flow are derived and transformed into a system of ordinary differential equations using a suitable similarity transformations. A numerical computation of shooting technique is employed along Runge Kutta method of fourth order with the help of Newton-Raphson algorithm to compute the solution and analyze the behavior of velocity, temperature, concentration, skin friction, heat and mass transfer rates graphically for various non-dimensional parameters which are controlling the flow of the physical system. The results of the numerical scheme are validated and a numerical comparison has been made with the available literature in the absence of some parameters and it is found to be in good agreement.

Variable Fluid Property Effect on Heat Transfer and Frictional Flow Characteristics of Water Flowing through Microchannel

The effects of temperature-dependent viscosity and thermal conductivity on heat transfer and frictional flow characteristics of water flowing through a microchannel are numerically investigated in this work. The hydrodynamically and thermally developing flow with no-slip, notemperature jump, and constant wall heat flux boundary condition is numerically studied using 2D continuum-based conservation equations. A significant deviation in Nusselt number from conventional theory is observed due to flattening of axial velocity profile due to temperaturedependent viscosity variation. The Nusselt number shows a significant deviation from conventional theory due to flattening of the radial temperature profile due to temperature-dependent thermal conductivity variation. It is noted that the deviation in Nusselt number from conventional theory is maximum for combined temperature-dependent viscosity and thermal conductivity variations. The effects of temperature-dependent viscosity and thermal conductivity on the Fanning friction factor are also investigated. Additionally, the effects of variable fluid properties on Poiseuille number, Prandtl number, and Peclet number are also investigated.

MHD squeeze flow and heat transfer of a nanofluid between parallel disks with variable fluid properties and transpiration

BackgroundThe purpose of the study is to investigate the effects of variable fluid properties, the velocity slip and the temperature slip on the time-dependent MHD squeezing flow of nanofluids between two parallel disks with transpiration.MethodsThe boundary layer approximation and the small magnetic Reynolds number assumptions are used. The non-linear governing equations with appropriate boundary conditions are initially cast into dimensionless form by using similarity transformations and then the resulting equations are solved analytically via Optimal Homotopy Analysis Method (OHAM). A detailed parametric analysis is carried out through plots and tables to explore the effects of various physical parameters on the velocity temperature and nanoparticles concentration fields.ResultsThe velocity distribution profiles for transpiration (suction/blowing) are parabolic in nature. In general, at the central region, these profiles exhibit the cross-flow behavior and also exhibit the dual behavior with the increase in the pertinent parameters. The temperature distribution reduces in the case of suction whereas the reverse trend is observed in the case of injection.ConclusionThe effects of temperature dependent thermophysical properties are significant on the flow field. For higher values of the fluid viscosity parameter, the velocity field increases near the walls. However, the transpiration effects are dominant and exhibit the cross-flow behavior as well as the dual behavior. The temperature and the concentration fields are respectively the increasing functions of the variable thermal conductivity and the variable species diffusivity parameters.

Physical Effects of Variable Fluid Properties on Laminar Gas Microconvective Flow

AbstractThe physical effects of variable fluid properties on heat transfer and frictional flow characteristics of laminar gas microconvective flow are investigated in this research. The fully developed flow through a microtube is studied numerically by using 2D continuum‐based governing equations. The physical effects induced due to variations in gas density with pressure and temperature, and gas viscosity, thermal conductivity, and specific heat with temperature are analyzed. Numerical results reveal that the heat transfer and frictional flow characteristics of laminar gas microflow are drastically affected by these physical effects. Hence, this research suggests that these physical effects need to be well considered in the applications of laminar gas microconvection based on large temperature gradients, for example, the design of microchannel heat sinks, and the flow cannot be generally considered as a constant property flow, as in conventional channels.

Lie group analysis of hydromagnetic flow and heat transfer of a power-law fluid over stretching surface with temperature-dependent viscosity and thermal conductivity

The symmetry group of MHD boundary layer flow and heat transfer of a non-Newtonian power-law fluid over a stretching surface under the effects of variable fluid properties is investigated. The similarity equations with the corresponding boundary conditions are solved numerically by using a shooting method with the fourth order Runge–Kutta integration scheme. Comparisons of the numerical method with the existing results in the literature are made and obtained an excellent agreement. It is observed that the heat transfer rate diminishes with an increase in magnetic parameter and variable thermal conductivity parameter. Further, the opposite influence is found with an increase in variable viscosity parameter.

Effects of Variable Fluid Properties on MHD Flow and Heat Transfer over a Stretching Sheet with Variable Thickness

AbstractThe influence of temperature-dependent fluid properties on flow and heat transfer of an electrically conducting fluid over a stretching sheet with variable thickness in the presence of a transverse magnetic field is analyzed. Using similarity transformations, the governing coupled non-linear partial differential equations (momentum and energy equations) are transformed into a system of coupled non-linear ordinary differential equations and are solved numerically by Keller-box method. For increasing values of the wall thickness parameter, the analysis reveals quite interesting flow and heat transfer patterns. The effects of the temperature dependent viscosity, the wall velocity power index, the thermal conductivity, the wall temperature parameter and the Prandtl number on the flow and temperature fields are presented. The obtained numerical results are compared with the available results in the literature for some special cases and are found to be in excellent agreement. The skin friction and the wall temperature gradient are presented for different values of the physical parameters and the salient features are analyzed.

Effect of melting heat transfer and thermal radiation on Casson fluid flow in porous medium over moving surface with magnetohydrodynamics

In this study, the effects of variable fluid properties on heat transfer in MHD Casson fluid melts over a moving surface in a porous medium in the presence of the radiation are examined. The relevant similarity transformations are used to reduce the governing equations into a system of highly nonlinear ordinary differential equations and those are then solved numerically using the Runge–Kutta–Fehlbergmethod. The effects of different controlling parameters, namely, the Casson parameter,melting and radiation parameters, Prandtl number,magnetic field, porosity, viscosity and the thermal conductivity parameters on flow and heat transfer are investigated. The numerical results for the dimensionless velocity and temperature as well as friction factor and reducedNusselt number are presented graphically and discussed. It is found that the rate of heat transfer increases as the Casson parameter increases.

Analysis of MHD Forced Convective Flow of Variable Fluid Properties over a Saturated Porous Medium with Thermal Radiation Effect

The present paper addresses the problem of MHD forced convective flow in a fluid saturated porous medium with Brinkman-Forchheimer model, which is an important physical phenomena in engineering applications. The paper extends the previous models to account for effects of variable fluid properties on the forced convective flow through a porous medium in the presence of radiative heat loss using bivariate spectral relaxation method (BSRM). The dynamic viscosity and thermal conductivity of the newtonian fluid are assumed to vary linearly respectively, with temperature whereas the contribution of thermal radiative heat loss is based on Rosseland diffussion approximation. The flow model is described and expressed in form of a highly coupled nonlinear system of partial differential equations. The method of solution BSRM as proposed by Motsa [25] seeks to decouple the original system of PDEs to form a sequence of equations that can be solved in a computationally efficient manner. BSRM is an approach that applies spectral collocation independently in all underlying independent variable is executed to obtain approximate solutions of the problem. The proposed algorithm is supposed to be a very accurate, convergent and very effective in generating numerical results. The results obtained show a significant effects of the flow control parameters on the fluid velocity and temperature respectively. Consequently, the wall shear stress and local heat transfer rate of the present paper are compared with the available results in literatures. Remarkable impacts and a good agreement are found.

Effects of variable fluid properties and thermophoresis on unsteady forced convective boundary layer flow along a permeable stretching/shrinking wedge with variable Prandtl and Schmidt numbers

In this paper, the effects of variable fluid properties and thermophoresis on unsteady forced convective boundary layer flow along a permeable stretching/shrinking wedge are studied numerically. The analysis accounts for temperature dependent viscosity and thermal conductivity. The governing time dependent nonlinear partial differential equations are reduced to a set of nonlinear ordinary differential equations by the similarity transformations. The resulting local similarity equations are solved numerically by Nachtsheim–Swigert shooting iteration technique with sixth order Runge–Kutta integration scheme. Comparison with previously published work is performed and the results are found to be in excellent agreement. Numerical results for the non-dimensional velocity, temperature and concentration profiles as well as the variable Prandtl number and the variable Schmidt number are displayed graphically for several sets of material parameters. The effects of the model parameters on the local skin friction coefficient, the rate of heat and mass transfer, and the thermophoretic particle deposition velocity are also tabulated. The results show that for the flow with variable thermal conductivity, the Prandtl number as well as the Schmidt number varies significantly within the boundary layer. Thus, in any physical model where fluid transport properties are temperature dependent, the Prandtl number and the Schmidt number within the boundary layer should be considered as variables rather than constants.

Effect of Variable Fluid Properties on Natural Convection of Nanofluids in a Cavity with Linearly Varying Wall Temperature

The present study analyzed convective heat transfer and fluid flow characteristics of nanofluid in a two-dimensional square cavity under different combinations of thermophysical models of nanofluids. The right vertical wall temperature is varying linearly with height and the left wall is maintained at low temperature whereas the horizontal walls are adiabatic. Finite volume method is used to solve the governing equations. Two models are considered to calculate the effective thermal conductivity of the nanofluid and four models are considered to calculate the effective viscosity of the nanofluid. Numerical solutions are carried out for different combinations of effective viscosity and effective thermal conductivity models with different volume fractions of nanoparticles and Rayleigh numbers. It is found that the heat transfer rate increases for Models M1 and M3 on increasing the volume fraction of the nanofluid, whereas heat transfer rate decreases for Model M4 on increasing the volume fraction of the nanoparticle. The difference among the effective dynamic viscosity models of nanofluid plays an important role here such that the average Nusselt number demonstrates an increasing or decreasing trend with the concentration of nanoparticle.