Effect Of Temperature-dependent Viscosity Research Articles

Effect of temperature-dependent viscosity on pressure drop in axisymmetric channel flows

Effect of temperature-dependent viscosity on pressure drop in axisymmetric channel flows

Temperature-dependent viscosity effect on forced convective CH3OH–Fe3O4 nanofluid flow through annular duct

The importance of Methanol can be guessed from its usage as in the preparation of methyl tertiary butyl ether (MTBE) fuel, ascetic acid, formaldehyde, metabolize food, biodiesel, pharmaceutical ingredients and products, energy related applications and many more. In this research work, we numerically analyze the impact of temperature-dependent viscosity on flow and heat transfer of Methanol Iron oxide, CH3OH–Fe3O4 nanofluid through annular sector duct. The effects of pertinent parameters corresponding to temperature-dependent viscosity, m, Fe3O4 nanoparticles’ contribution, n and geometrical configuration (i.e. [Formula: see text] and N), are revealed graphically by velocity contours, isotherms, velocity and temperature profiles, and discussed physically. Both parameters m and n suppress the velocity and temperature profiles by increasing the friction factor [Formula: see text] and average Nusselt number [Formula: see text]. Same impacts of m and n have been observed for all values of [Formula: see text] and N.

Acoustic radiation force on a spherical thermoviscous particle in a thermoviscous fluid including scattering and microstreaming.

We derive general analytical expressions for the time-averaged acoustic radiation force on a small spherical particle suspended in a fluid and located in an axisymmetric incident acoustic wave. We treat the cases of the particle being either an elastic solid or a fluid particle. The effects of particle vibrations, acoustic scattering, acoustic microstreaming, heat conduction, and temperature-dependent fluid viscosity are all included in the theory. Acoustic streaming inside the particle is also taken into account for the case of a fluid particle. No restrictions are placed on the widths of the viscous and thermal boundary layers relative to the particle radius. We compare the resulting acoustic radiation force with that obtained from previous theories in the literature, and we identify limits, where the theories agree, and specific cases of particle and fluid materials, where qualitative or significant quantitative deviations between the theories arise.

Parametric simulation of hybrid nanofluid flow consisting of cobalt ferrite nanoparticles with second-order slip and variable viscosity over an extending surface

Abstract This study explores the unsteady hybrid nanofluid (NF) flow consisting of cobalt ferrite (CoFe2O4) and copper (Cu) nano particulates with natural convection flow due to an expanding surface implanted in a porous medium. The Cu and CoFe2O4 nanoparticles (NPs) are added to the base fluid water to synthesize the hybrid NF. The effects of second-order velocity slip condition, chemical reaction, heat absorption/generation, temperature-dependent viscosity, and Darcy Forchheimer are also assessed in the present analysis. An ordinary differential equation system is substituted for the modeled equations of the problem. Further computational processing of the differential equations is performed using the parametric continuation method. A validation and accuracy comparison are performed with the Matlab package BVP4C. Physical constraints are used for presenting and reviewing the outcomes. With the increase in second-order velocity slip condition and unsteady viscosity, the rates of heat and mass transition increase significantly with the variation in Cu and Fe2O4 NPs. The findings suggest that the uses of Cu and Fe2O4 in ordinary fluids might be useful in the aerodynamic extrusion of plastic sheets and extrusion of a polymer sheet from a dye.

Impacts of entropy generation in radiative peristaltic flow of variable viscosity nanomaterial

Current analysis highlights the aspects of different nanoparticles in peristalsis with entropy generation. Mathematical equations of considered problem are modelled via conservation laws for mass, momentum and energy. Such equations contain variable viscosity, nonlinear thermal radiation, viscous dissipation, heat generation/absorption and mixed convection aspects. Boundary conditions comprise the second order velocity and first order thermal slip effects. Entropy expression is obtained by utilization thermodynamics. Simplified and dimensionless forms of the considered conservative laws are obtained through lubrication technique. Resulting system of equations subject to the considered boundary conditions is solved numerically via built-in shooting procedure in Mathematica. Such numerical procedure is very suitable to obtain numerical results directly and fastly in the form of graphs. Further all the considered flow quantities are discussed graphically for the significant parameters of interest in detail. Both velocity and temperature are decreasing against large volume fraction parameter. Increasing temperature dependent viscosity effects decrease the entropy and enhance the Bejan number.

Powell-Eyring Fluid Flow Over a Stretching Surface with Variable Properties

The objective of this study is to investigate the effect of temperature dependent viscosity and thermal conductivity on the stretching surface and heat transfer of a Powell-Eyring fluid with the effect of nonlinear thermal radiation. The Prandtl number is also considered to be varying within the boundary layer. The governing model which consists of a set of coupled non-linear partial differential equations is converted into a system of ordinary differential equations via suitable similarity transformations and then solved by a recent and reliable numerical method called the spectral quasi-linearization method is used in the computational analysis. The result shows that there is large variation in the value of the Nusselt number and skin friction co-efficient.

Exploration of the dynamics of non-Newtonian Casson fluid subject to viscous dissipation and Joule heating between parallel walls due to buoyancy forces and pressure

Vertical channels between two flat plates have a wide range of engineering applications, such as heat exchangers, chemical processing equipment, electronic component heat dissipation, and so on. Therefore, this analysis examines the significance of variable properties on the dynamics of Casson fluid in a vertical channel due to mixed convection when thermal radiation and Joule heating are significant. The combined effects of temperature-dependent plastic dynamics viscosity and temperature-dependent thermal conductivity are analyzed. Moreover, the evaluation of heat transfer is further supported by viscous dissipation. The nondimensional governing equations are elucidated analytically by employing the perturbation technique and numerically by Runge–Kutta method with the shooting technique. The effects of numerous dimensionless parameters on fluid flow are featured through graphs. In addition, the heat transfer rate and the skin friction coefficient are computed and scrutinized. It is reported that velocity depicts enhancing behavior for higher values of the Casson fluid and slip parameters. It has also been observed that the fluid temperature decreases with an increase in the thermal conductivity parameter.

Two-Phase Flow of Eyring–Powell Fluid with Temperature Dependent Viscosity over a Vertical Stretching Sheet

In this work, the mixed convection flow of non-Newtonian Eyring–Powell fluid with the effects of temperature dependent viscosity (TDV) were studied together with the interaction of dust particles under the influence of Newtonian Heating (NH) boundary condition, which assume to move over a vertical stretching sheet. Alternatively, the dusty fluid model was categorized as a two-phase flow that consists of phases of fluid and dust. Through the use of similarity transformations, governing equations of fluid and dust phases are reduced into ordinary differential equations (ODE), then solved by efficient numerical Keller–box method. Numerical solution and asymptotic results for limiting cases will be presented to investigate how the flow develops at the leading edge and its end behaviour. Comparison with the published outputs in literature evidence verified the precision of the present results. Graphical diagrams presenting velocity and temperature profiles (fluid and dust) were conversed for different influential parameters. The effects of skin friction and heat transfer rate were also evaluated. The discovery indicates that the presence of the dust particles have an effect on the fluid motion, which led to a deceleration in the fluid transference. The present flow model can match to the single phase fluid cases if the fluid particle interaction parameter is ignored. The fluid velocity and temperature distributions are always higher than dust particles, besides, the opposite trend between both phases is noticed with β. Meanwhile, both phases share the similar trend in conjunction with the rest factors. Almost all of the temperature profiles are not showing a significant change, since the viscosity of fluid is high, which can be perceived in the figures. Furthermore, the present study extends some theoretical knowledge of two-phase flow.

Role of viscosity in the preferential concentration of heated, bidispersed particles

We study the effect of temperature-dependent viscosity on the preferential concentration of bidispersed, externally-heated solid particles in decaying isotropic turbulence via direct numerical simulations (DNS). More specifically, we investigate the role of liquid- and gas-like viscosity–which respectively decrease and increase with temperature–on the preferential concentration of small and large particles due to turbulence. The bidispersed particles enhance the overall distribution compared to monodispersed flows as the voids created by the particles of one size are occupied by the other particles. Particle clusters emerge irrespective of the Stokes number although the clustering characteristics differ based on the functional form of the temperature-dependent viscosity. When particles are externally heated in a variable viscosity flow, the Kolmogorov-based Stokes number, Stη, is not sufficient to predict preferential concentration. Increased clustering is observed, especially for small-sized particles, as the fluid is heated and turbulence decays. This increased clustering is explained through a viscous capturing mechanism in which the initial clustering, prior to the onset of heating, is responsible for the creation of local hot-spots in the flow as the particles are heated. In a gas, these higher temperature regions have higher viscosity which cause other particles to be captured due to the increased drag. The increased drag of the gas results in a lower fluid-particle drift velocity as compared to the liquid, despite the significantly lower turbulent kinetic energy of the flow. The relative distribution of the particles as a function of vorticity and strain rate magnitude reveals a bimodal distribution in which a higher proportion of the particles aggregate in mid- and high strain/vorticity regions as the turbulence decays.

Dynamics of Unsteady Flow of Chemically Reactive Upper-Convected Maxwell Fluid with Temperature-Dependent Viscosity: Keller Box Analysis

The heat and mass transfer characteristics of unsteady flow of incompressible chemically reactive upper-convected Maxwell fluid along a stretching surface in the presence of temperature-dependent viscosity has been studied. The theoretical analysis on heat and mass transfer over a stretching sheet is investigated for numerical analysis. With the use of stream function formulation, the governing boundary layer equations of momentum, energy, and concentration are reduced to a set of linked ordinary differential equations. The nonlinear ordinary differential equations are then solved numerically by using the Keller Box method. The physical behavior of governing parameters on velocity, temperature, and concentration profiles and the local skin friction coefficient and heat and mass transfer rates are graphed and tabulated. The physical impact of Maxwell parameter β, unsteadiness parameter M, Schmidt number Sc, Prandtl number Pr, reaction rate parameter γ, and variable viscosity parameter ε on the heat and mass transfer has been examined along the stretching surface numerically. The novelty of the present work is to examine the importance of destructive reaction and contractive reaction on the dynamics of upper-convected Maxwell fluid flow in the presence of temperature-dependent viscosity effects. It is observed an interesting behavior of temperature distribution and concentration profile is noted for lower value of viscosity parameter ε in the presence of chemical reaction. It is also found that skin friction and the rate of heat transfer are decreased by increasing the variable viscosity parameter ε .

NUMERICAL STUDY OF THE INFLUENCE OF TEMPERATURE-DEPENDENT VISCOSITY ON THE UNSTEADY LAMINAR FLOW AND HEAT TRANSFER OF A VISCOUS INCOMPRESSIBLE FLUID DUE TO A ROTATING DISC

In this article, the effect of temperature-dependent viscosity (TVD) on the unsteady laminar flow and heat transfer (HT) of a viscous incompressible fluid due to a rotating disc (RD) has been investigated numerically by exploiting an in-house numerical code. A set of time-dependent, axisymmetric, and non-linear partial differential equations which govern the fluid flows and heat transfer are reduced to non-linear local non-similarity ordinary differential equations by introducing a newly developed group of transformations for different time regimes. Three different solution methods, such as, (i) perturbation solution method for small t, (ii) asymptotic solution method for large t, and (iii) implicit finite difference method for the entire t regime, have been applied to solve the resulting equations treating t as the time-dependent rotating parameter. The local radial skin friction, tangential skin friction and the heat transfer are computed at the surface of the disc for different numerical parameters, such as, Prandtl number, Pr and the viscosity-variation parameter, e. Besides, the key dimensionless quantities such as velocity and temperature profiles, which are inherently linked with the boundary layer thickness, are presented graphically for different values of e while Pr = 0.72. It is found that the dimensionless radial, tangential and axial velocity profiles decrease as e increases, and consequently, the momentum boundary layer thickness is decreased. On the other hand, the non-dimensional temperature profiles are increased owing to the increasing values of e, and this effect eventually leads to a small increment in the thermal boundary layer thickness.

Comment on the paper “Effect of temperature-dependent viscosity on the onset of Bénard–Marangoni ferroconvection in a ferrofluid saturated porous layer, C. E. Nanjundappa, B. Savitha, B. Arpitha Raju, I. S. Shivakumara, Acta Mechanica 225 (2014) 835–850”

Comment on the paper “Effect of temperature-dependent viscosity on the onset of Bénard–Marangoni ferroconvection in a ferrofluid saturated porous layer, C. E. Nanjundappa, B. Savitha, B. Arpitha Raju, I. S. Shivakumara, Acta Mechanica 225 (2014) 835–850”

Natural Convection Flow over a Vertical Permeable Circular Cone with Uniform Surface Heat Flux in Temperature-Dependent Viscosity with Three-Fold Solutions within the Boundary Layer

The aim of this study is to investigate the effects of temperature-dependent viscosity on the natural convection flow from a vertical permeable circular cone with uniform heat flux. As part of numerical computation, the governing boundary layer equations are transformed into a non-dimensional form. The resulting nonlinear system of partial differential equations is then reduced to local non-similarity equations which are solved computationally by three different solution methodologies, namely, (i) perturbation solution for small transpiration parameter (ξ), (ii) asymptotic solution for large ξ, and (iii) the implicit finite difference method together with a Keller box scheme for all ξ. The numerical results of the velocity and viscosity profiles of the fluid are displayed graphically with heat transfer characteristics. The shearing stress in terms of the local skin-friction coefficient and the rate of heat transfer in terms of the local Nusselt number (Nu) are given in tabular form for the viscosity parameter (ε) and the Prandtl number (Pr). The viscosity is a linear function of temperature which is valid for small Prandtl numbers (Pr). The three-fold solutions were compared as part of the validations with various ranges of Pr numbers. Overall, good agreements were established. The major finding of the research provides a better demonstration of how temperature-dependent viscosity affects the natural convective flow. It was found that increasing Pr, ξ, and ε decrease the local skin-friction coefficient, but ξ has more influence on increasing the rate of heat transfer, as the effect of ε was erratic at small and large ξ. Furthermore, at the variable Pr, a large ξ increased the local maxima of viscosity at large extents, particularly at low Pr, but the effect on temperature distribution was found to be less significant under the same condition. However, at variable ε and fixed Pr, the temperature distribution was observed to be more influenced by ε at small ξ, whereas large ξ dominated this scheme significantly regardless of the variation in ε. The validations through three-fold solutions act as evidence of the accuracy and versatility of the current approach.

Analysis of temperature-dependent viscosity effect on wire coating using MHD flow of incompressible third-grade nanofluid filled in cylindrical coating die

The convective heat and mass propagation inside dies are used to determine the characteristics of coated wire products. As a result, comprehending the properties of polymerization mobility, heat mass transport, and wall stress concentration is crucial. The wire coating procedure necessitates an increase in thermal performance. As a result, this research aims to find out how floating nanoparticles affect the mass and heat transport mechanisms of third-grade fluid in the posttreatment for cable coating processes in presence of a magnetic field with time-dependent viscosity. For nanofluids, the Buongiorno model is used. The model equations are developed using continuity, momentum, and energy in the presence of nanoparticle and time-dependent variable viscosity. We propose a few nondimensional transformations that are relevant. The numerical technique Runge-Kutta fourth method is used to generate numerical solutions for nonlinear systems. Pictorial depictions are used to examine the effects of various factors in the nondimensional flow. Furthermore, the numerical results are also verified analytically using Homotopy Analysis Method (HAM). The analytical findings of this investigation reveal that within the Reynolds modeling, the stress on the whole wire surface combined shear forces at the surface predominate the Vogel model. The contribution of nanomaterials on force on the entire surface of wire and shear forces at the surface appears positive. A non-Newtonian feature can increase the capping substance’s velocity. This research could aid in the advancement of wire coating technologies. For the very first instance, the significance of nanotechnology during wire coating evaluation is explored utilizing time-dependent variable viscosity regarding the magnetic field. For time-dependent viscosity, two alternative models are useful. The Lorentzian strength (a resistive form of force) increases in magnetic strength increases. As a result of the increased magnetic field, the motion of the polymerization in a die decreases. It is clear that increasing the intensity of Nb increases the heat transfer. The innovative fragment of the present study is to scrutinize the magnetized third-grade nanofluid for wire coating with variable viscosity inside the pressurized coating die, which still not has been elaborated in the available works to date. Consequently, in the restrictive sense, the existing work is associated with available work and originated in exceptional agreement.

Effect of temperature-dependent viscosity on hydromagnetic unallied flow

The present article focuses on radiative hydromagnetic unallied stagnation point flow past a horizontal extending surface under varying viscosity concerning temperature. To understand the physical behaviour of the physical model, we converted the scheme of nonlinear partial differential equations to ordinary differential equations using suitable similarities. Matlab bvp5c procedure is adopted to obtain the computational outcomes. Also, we graphed the flow and temperature fields with and without the influence of magnetic field for various controlling non-dimensional parameters such as thermal radiation, variable viscosity, Prandtl number, velocity and temperature ratio parameters, etc. Moreover, Nusselt number and wall friction are evaluated and presented in the table for both criteria. It is noticed that the heat transfer rate is high in the presence of a magnetic field when compared to the absence of a magnetic field. Thermal radiation, viscosity variation, and temperature ratio parameters effectively stabilise the axial flow velocity.

Rayleigh-Benard convection in a binary fluid-saturated anisotropic porous layer with variable viscosity effect

Rayleigh-Benard convection due to buoyancy that occurred in a horizontal binary fluid layer saturated anisotropic porous media is investigated numerically. The system is heated from below and cooled from above. The temperature-dependent viscosity effect was applied to the double-diffusive binary fluid and the critical Rayleigh number for free-free, rigid-free, and rigid-rigid representing the lower-upper boundary were obtained by using the single-term Galerkin expansion procedure. Both boundaries are conducted to temperature. The effect of temperature-dependent viscosity, mechanical anisotropy, thermal anisotropy, Soret, and Dufour parameters on the onset of stationary convection are discussed and shown graphically.

Temperature-dependent variable viscosity and thermal conductivity effects on non-Newtonian fluids flow in a porous medium

Purpose The purpose of this paper is to consider the simultaneous flow of Casson Williamson non Newtonian fluids in a vertical porous medium under the influence of variable thermos-physical parameters. Design/methodology/approach The model equations are a set of partial differential equations (PDEs). These PDEs were transformed into a non-dimensionless form using suitable non-dimensional quantities. The transformed equations were solved numerically using an iterative method called spectral relaxation techniques. The spectral relaxation technique is an iterative method that uses the Gauss-Seidel approach in discretizing and linearizing the set of equations. Findings It was found out in the study that a considerable number of variable viscosity parameter leads to decrease in the velocity and temperature profiles. Increase in the variable thermal conductivity parameter degenerates the velocity as well as temperature profiles. Hence, the variable thermo-physical parameters greatly influence the non-Newtonian fluids flow. Originality/value This study considered the simultaneous flow of Casson-Williamson non-Newtonian fluids by considering the fluid thermal properties to vary within the fluid layers. To the best of the author’s knowledge, such study has not been considered in literature.

Effects of wall temperature and temperature-dependent viscosity on maximum spreading of water-in-oil emulsion droplet

The study is focused on the spreading dynamics of the droplets of n-decane and water-in-oil emulsions based on n-decane and isoparaffinic oil stabilized by different nonionic surfactants. The droplets fall on a solid glass surface heated up to 70–390 °C at Weber numbers of 100–500 and Ohnesorge numbers of 0.001–0.008. Five hydrodynamic outcomes of the droplet impact on a heated surface are experimentally identified, including deposition, bouncing, contact splashing, film splashing, and rebound. The maximum spreading of droplets of the liquids is quantified given their temperature-dependent dynamic viscosity. As a result, a universal empirical model for maximum droplet spreading diameter, βmax=(T*WeOhT–1)1/8 + 0.15, is proposed, taking into account the overall effects of temperature-dependent dynamic viscosity, surface tension, and explicit impact surface temperature term. The model has been successfully tested using the experimental data on the maximum droplet spreading diameters for pure hydrocarbons, commercial hydrocarbon liquid fuels, and biofuel at Weber numbers of 60–900, Ohnesorge numbers of 0.002–0.015, and impact surface temperature of 25–210 °C. The values of the maximum droplet spreading diameter predicted by the model are compared with those determined by the empirical expression by Bhat et al. (2019) for single- and multi-component liquid fuels, also involving an explicit surface temperature term. The model by Bhat et al. (2019) is modified by introducing the temperature-dependent viscosity leading to the significant decrease in the relative mean error between the experimental and predicted values of the maximum droplet spreading diameter. The findings related to the no-slip condition for the viscous liquids are critically important in modeling the conjugate problems of fluid mechanics and heat mass transfer used in the fuel-air mixture formation in combustion chambers.

Could the Réunion plume have thinned the Indian craton?

AbstractThick and highly viscous roots are the key to cratonic survival. Nevertheless, cratonic roots can be destroyed under certain geological scenarios. Eruption of mantle plumes underneath cratons can reduce root viscosity and thus make them more prone to deformation by mantle convection. It has been proposed that the Indian craton could have been thinned due to eruption of the Réunion plume underneath it at ca. 65 Ma. In this study, we constructed spherical time-dependent forward mantle convection models to investigate whether the Réunion plume eruption could have reduced the Indian craton thickness. Along with testing the effect of different strengths of craton and its surrounding asthenosphere, we examined the effect of temperature-dependent viscosity on craton deformation. Our results show that the plume-induced thermomechanical erosion could have reduced the Indian craton thickness by as much as ~130 km in the presence of temperature-dependent viscosity. We also find that the plume material could have lubricated the lithosphere-asthenosphere boundary region beneath the Indian plate. This could be a potential reason for acceleration of the Indian plate since 65 Ma.

Nonlinear thermal radiation and temperature dependent viscosity effects on MHD heat and mass transfer in a thin liquid film over a stretching surface

This paper describes nonlinear thermal radiation effects on MHD heat and mass transfer in a thin liquid film over a permeable unsteady stretching surface taking temperature-dependent fluid viscosity with convective boundary condition. For the non-linearity of the momentum, energy and mass diffusion equations, the problem is solved numerically. At first, Similarity transformations is used to the governing equations to reduce the equations into a set of ordinary differential equations. Then the resulting nonlinear ordinary differential equations are solved using Runge-Kutta-Felberg method with shooting technique. Different physical parameters effects on heat and mass transfer in a thin liquid film are presented graphically. It is found that increase in the unsteadiness parameter leads to increase in the velocity distribution, temperature and concentration gradient. Further, increase in the value of magnetic parameter results in a decrease in the velocity profile and increase in the temperature and concentration gradient. For enhancement of thermal radiation decreases the temperature gradient of the thin film flow. Also, for increase in viscosity variation parameter is to decrease velocity distribution but reverse effects shown in case of temperature and concentration gradient.