Temperature Dependent Variable Viscosity Research Articles

Analysis of thermal conductivity variation in magneto-hybrid nanofluids flow through porous medium with variable viscosity and slip boundary

Hybrid nanoparticles, which are nanoparticles composed of multiple materials or phases, find applications in various fields due to their unique properties resulting from the combination of different materials. In such fluids, viscosity changes significantly in response to alterations in temperature or pressure. For example, these fluids become less viscous as they are heated and more viscous as they are cooled. Similarly, in certain situations, the application of a temperature variation can cause a change in viscosity. This property is commonly observed in materials like polymers and some oils. The article aims to investigate the heat transfer and flow behavior of fluid from an elastic sheet of hybrid nanoparticles, considering the temperature-dependent variable viscosity and thermal conductivity. The obtained equations for the mathematical model are partial differential equations converted to ODEs by applying a suitable similarity transformation. The findings show that the magnetic field opposes fluid motion. Our main findings are that adding nanoparticles to the base fluid significantly increased its heat conductivity. This improvement has great potential for uses requiring effective heat transmission, especially in engineering systems where heat dissipation plays a crucial role. The study also reveals the complex relationships that influence thermal conductivity, including slip boundary effects, viscosity fluctuations, magnetohydrodynamic effects, and porous media dynamics. Understanding these interactions is critical for optimizing heat transport processes in porous media applications. Comprehending these interplays is essential for refining heat transport mechanisms in applications involving porous media. The graphical representations are used to explain the physical behavior of various model parameters. Previous outcomes are also contrasted with the current ones. The findings show that the magnetic field opposes fluid motion.We range the subsequent list of values for parameters in every graph unless indicated accordingly.ϵ=0.1,Pr=2,M=0.5,R=0.2,K=5,fw=0.1,s=0.1 ,λ=1,φ1=0.02,φ2=0.04.

Bioconvective flow of a variable properties hybrid nanofluid over a spinning disk with Arrhenius activation energy, Soret and Dufour impacts

This paper explores the heat and mass transfer by hybrid nanofluids flow over a spinning disk in the presence of oxytactic microorganisms. During this study, the Soret and Dufour together with Lorentz force impacts are considered. The worked nano-mixture is assumed to be having time-dependent dynamic viscosity and thermal conductivity and its components are methanol-based hybrid nanofluid comprising CuO and MgO nanoparticles. The disk surface is permeable and various aspects such as thermal radiation, heat generation and Arrhenius activation energy are taken into account. The governing equations are treated numerically and suitable similar transformations are introduced. The obtained results revealed that both of the velocity and temperature gradients are enhanced as the absolute values of unsteadiness parameter and nanoparticles concentrations are rising. However, the flow is slowdown as the temperature-dependent variable viscosity parameter is growing.

Combined Effect of Radiant Heat, Local Nusselt Number and Skin Friction Coefficient of a Third Grade Fluid through a Channel Flow in a Saturated Porous Medium

This paper investigates the combined effects of radiant heat, local Nusselt number and Skin friction coefficient on a channel flow of third grade fluid in the presence of saturated porous medium. It is assumed that the fluid has temperature-dependent variable viscosity and thermal conductivity. The non-linear governing differential equations are obtained and tackled numerically using Spectral element technique and C++ programming language. Increase in the values of radiation parameter and third grade material parameter consequently increase the local Nusselt number and skin friction coefficient. Graphical results showing the effects of various physical parameters are presented and discussed quantitatively. It is concluded that Williamson’s fluid parameter served as a cooling factor in diverse improved technological processes in order to avoid different machines from overheating and enhance their efficiencies.

Non-similar modeling for the stagnation point mixed convection nanofluid flow with the temperature-dependent variable viscosity

In this work, a modified model for heat and mass transfer of mixed convection nanofluid flow over a stretching sheet is investigated. The model is described in form of partial differential equations (PDEs) and further, it is reduced to a dimensionless system of nonlinear PDEs. The main feature of the current study is to employ a non-similarity method that can be used for non-similar problems. The coupled ordinary differential equations are tackled by the MATLAB built-in solver bvp4c. The graphs for velocity, temperature, and concentration profiles are obtained with varying dimensionless parameters. Also, numerical values for quantities of physical interest skin friction coefficient, local Nusselt number and local Sherwood number are given through tables. By considering the effects of variable viscosity, an increase in velocity profile is found for growing values of the Grashof number.

Antioxidant, Cytotoxic, and Rheological Properties of Canola Oil Extract of Usnea barbata (L.) Weber ex F.H. Wigg from Călimani Mountains, Romania.

Usnea genus (Parmeliaceae, lichenized Ascomycetes) is a potent phytomedicine, due to phenolic secondary metabolites, with various pharmacological effects. Therefore, our study aimed to explore the antioxidant, cytotoxic, and rheological properties of Usnea barbata (L.) Weber ex F.H. Wigg (U. barbata) extract in canola oil (UBO) compared to cold-pressed canola seed oil (CNO), as a green solvent used for lichen extraction, which has phytoconstituents. The antiradical activity (AA) of UBO and CNO was investigated using UV-Vis spectrophotometry. Their cytotoxicity was examined in vivo through a brine shrimp lethality (BSL) test after Artemia salina (A. salina) larvae exposure for 6 h to previously emulsified UBO and CNO. The rheological properties of both oil samples (flow behavior, thixotropy, and temperature-dependent viscosity variation) were comparatively analyzed. The obtained results showed that UBO (IC50 = 0.942 ± 0.004 mg/mL) had a higher 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity than CNO (IC50 = 1.361 ± 0.008 mg/mL). Both UBO and CNO emulsions induced different and progressive morphological changes to A. salina larvae, incompatible with their survival; UBO cytotoxicity was higher than that of CNO. Finally, in the temperature range of 32–37 °C, the UBO and CNO viscosity and viscoelastic behavior indicated a clear weakening of the intermolecular bond when temperature increases, leading to a more liquid state, appropriate for possible pharmaceutical formulations. All quantified parameters were highly intercorrelated. Moreover, their significant correlation with trace/heavy minerals and phenolic compounds can be observed. All data obtained also suggest a possible synergism between lichen secondary metabolites, minerals, and canola oil phytoconstituents.

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.

Multi-objective optimization and performance assessment of microchannel heat sinks with micro pin-fins

In this study, laminar, steady-state microchannel flow and conjugate heat transfer in a microchannel heat sink (MCHS) with micro pin-fins were investigated numerically. Computational Fluid Dynamics (CFD) simulations were performed with ANSYS Fluent for heat and fluid flow in MCHSs with circular-, square- and diamond-shaped micro pin-fins of the same hydraulic diameter. Arrangements of micro pin-fins in the MCHS were optimized for each shape using a multi-objective genetic algorithm (MOGA) method called Non-dominated Sorting Genetic Algorithm (NSGA-II). The fluid entered the microchannel at channel Reynolds numbers ranging from 100 to 350, corresponding to circular- and square-shaped pin-fin Reynolds numbers ranging from 20 to 110 and diamond-shaped pin-fin Reynolds numbers ranging from 20 to 190. In all simulations, uniform heat flux of 60 W/cm2 was applied from the bottom surface of substrate. As the cooling fluid, water with temperature-dependent variable viscosity was assigned in the fluid domain and copper with constant thermophysical properties was considered for the entire solid domain. Design variables were selected in order to represent both the pin-fin arrangement and flow-characteristics: porosity number and pin-fin Reynolds number, respectively. As objective functions, pressure drop ratio was defined as the hydrodynamic performance indicator and the Nusselt number was chosen to represent the thermal performance. To represent the trade-off between two objective functions, optimization was conducted after a systematic parametric study and pareto-fronts were obtained. Optimized solutions of each pin-fin shape showed that square-shaped pin-fin was unfavorable compared with the performance of other shapes of pin-fins. Among all configurations, diamond-shaped pin-fins significantly enhanced heat transfer at an increased pressure drop ratio. Depending on the pin-fin shape, optimal configurations emerged over a wide range of porosity values mostly at the upper limit of the pin-fin Reynolds number, with average Nusselt numbers varying between 3 and 12 and corresponding pressure drop ratios varying between 1 and 12.

Heat Transfer and Flow Characteristics of Pseudoplastic Nanomaterial Liquid Flowing over the Slender Cylinder with Variable Characteristics

The present article investigates heat transfer and pseudoplastic nanomaterial liquid flow over a vertical thin cylinder. The Buongiorno model is used for this analysis. The problem gains more significance when temperature-dependent variable viscosity is taken into account. Using suitable similarity variables, nonlinear flow equations are first converted into ordinary differential equations. The generating structure is solved by the MATLAB BVP4C algorithm. Newly developed physical parameters are focused. It is observed that the heat transfer rate and the skin friction coefficient is increased remarkably because of mixing nano-particles in the base fluid by considering γb=1, 2, 3, 4 and λ=1, 1.5, 2, 2.5, 3. It is found that the temperature field increases by inclining the values of thermophoresis and Brownian motion parameters. It is also evaluated that the velocity field decreases by increasing the values of the curvature parameter, Weissenberg number and buoyancy ratio characteristics.

RK4 and HAM Solutions of Eyring-Powell Fluid Coating Material with Temperature-Dependent-Viscosity Impact of Porous Matrix on Wire Coating Filled in Coating Die: Cylindrical Co-ordinates.

In this work, we studied the impacts of transmitting light, nonlinear thermal, and micropolar fluid mechanics on a wire surface coating utilizing non-Newtonian viscoelastic flow. Models with temperature-dependent variable viscosity were used. The boundary layer equations governing the flow and heat transport processes were solved using the Runge–Kutta fourth order method. A distinguished constituent of this study was the use of a porous matrix that acted as an insulator to reduce heat loss. In this paper we discuss the effects of numerous development parameters, including , , and (non-Newtonian parameter, heat-producing parameter, viscosity parameter, variable viscosity parameter, porosity parameter, and Brinkman number, respectively). Furthermore, the effects of two other parameters, D and M, are also discussed as they relate to velocity and temperature distributions. We observed that the velocity profiles decreased with increasing values of . Fluid velocity increased as the values of , and increased, while it decreased when the values of , and increased. For increasing values of , the temperature profile showed increasing behavior, while showed decreasing behavior. Furthermore, the present work is validated by comparison with HAM and previously published work, with good results.

Thermodynamic analysis of a variable viscosity reactive hydromagnetic couette flow within parallel plates

This investigation is to consider the impact of a temperature-dependent variable viscosity of a reactive hydromagnetic Couette fluid flowing within parallel plates. The variable property of the fluid viscosity is thought to be an exponential relation of temperature under the impact of magnetic strength. The differential equations controlling the smooth movement of fluid and energy transfer are modeled and solved by using the series solution of modified Adomian decomposition technique (mADM). The outcomes are shown in tables and graphs for different estimations of thermophysical properties present in the flow regime together with the rate of entropy generation and irreversibility distribution outcome.
 Keywords: Reactive fluids, Couette Flow, variable viscosity, hydromagnetic and modified Adomian decomposition method (mADM).

Natural convection of fluid with variable viscosity and viscous dissipation from a heated vertical wavy surface in presence of magnetic field

ABSTRACT
 
 The present numerical work describes the effect of the temperature dependent variable viscosity and viscous dissipation on natural convection heat transfer boundary layer flow of a viscous incompressible electrically conducting fluid along a vertical wavy surface in presence of a transverse magnetic field. The wavy surface is maintained at uniform wall temperature that is higher than that of the ambient. A simple coordinate transformation is employed to transform the wavy surface into a flat plate. A marching finite difference scheme is used for present analysis. The numerical results, including the developments of the skin friction coefficients, the local Nusselt number, the streamlines as well as the isotherms are presented and discussed in detail. The results of this investigation illustrated that the skin friction coefficient increase with an increase of the variable viscosity and viscous dissipation parameter, while the local Nusselt number at the heated surface decrease with increasing values of variable viscosity, intensity of magnetic field and viscous dissipation parameter.

Probe of Radiant Flow on Temperature-Dependent Viscosity Models of Differential Type MHD Fluid

This paper numerically investigates the combined effects of the radiation and MHD on the flow of a viscoelastic Walters’ B liquid fluid model past a porous plate with temperature-dependent variable viscosity. To study the effects of variable viscosity on the fluid model, the equations of continuity, momentum with magnetohydrodynamic term, and energy with radiation term have been expanded. To understand the phenomenon, Reynold’s model and Vogel’s model of variable viscosity are also incorporated. The dimensionless governing equations are two-dimensional coupled and highly nonlinear partial differential equations. The highly nonlinear PDEs are transferred into ODEs with the assistance of suitable transformations which are solved with the help of numerical techniques, namely, shooting technique coupled with Runge–Kutta method and BVP4c solution method for the numerical solutions of governing nonlinear problems. Viscosity is considered as a function of temperature. Skin friction coefficient and Nusselt number are investigated through tables and graphs in the present probe. The behavior of emerging parameters on the velocity and temperature profiles is studied with the help of graphs. For Reynold’s model, we have shrinking stream lines and increasing three-dimensional graphs. γ and Pr are reduced for both models.

The variable viscosity effects on hydromagnetic couple stress heat generating porous fluid flow with convective wall cooling

This investigation examines the impact of temperature-dependent variable viscosity on hydromagnetic couple stress with internal heat generation through porous substances over convective cooling walls. The governing equations are formulated, derived and solved with the use of the collocation weighted residual method to provide solutions. The features of the solution as a function of the physical parameters of the problem are presented with the help of graphs. Notably, the impact of the temperature-dependent variable viscosity and heat source showed a remarkable impact on fluid velocity and temperature distributions along with the entropy generation rate.

Bénard–Taylor Convection in Temperature-Dependent Variable Viscosity Newtonian Liquids with Internal Heat Source

This study demonstrates a theoretical investigation of linear and weakly non-linear Rayleigh–Benard convection problem with rotation, variable viscosity and internal heat source. The linear stability analysis shows that an increase in the strength of rotation is to stabilize the system but an increasing internal heat generation and the thermorheological parameter destabilizes the system. The generalized Lorenz model derived for the problem is essentially fifth-order autonomous system of first ordered coupled differential equation with its coefficients depending on internal Rayleigh number, thermorheological parameter and Taylor number. The result on the parameter influence on critical Rayleigh number explains their influence on the Nusselt number as well. Quantification of heat transfer is made possible due to the numerical solution of the autonomous system. It is found that the effect of increasing the strength of rotation is found to have diminished heat transport but in the case of increasing internal Rayleigh number and thermorheological parameter enhances the same.

Prediction of oxide content and porosity in aluminum alloy castings

It is shown that forecasting the porosity of chill castings from aluminum alloys is possible using modern computer technology and melt model with temperature-dependent variable viscosity. The use of elastoviscoplastic model to solve such problems leads to unjustifi ed increase in the required computing resources.

Analysis of Transient Rivlin-Ericksen Fluid and Irreversibility of Exothermic Reactive Hydromagnetic Variable Viscosity

This study analyzes the unsteady Rivlin-Ericksen fluid and irreversibility of exponentially temperature dependent variable viscosity of hydromagnetic two-step exothermic chemical reactive flow along the channel axis with walls convective cooling. The non-Newtonian Hele-Shaw flow of Rivlin-Erickson fluid is driven by bimolecular chemical kinetic and unvarying pressure gradient. The reactive fluid is induced by periodic changes in magnetic field and time. The Newtons law of cooling is satisfied by the constant heat coolant convection exchange at the wall surfaces with the neighboring regime. The dimensionless non-Newtonian reactive fluid equations are numerically solved using a convergent and consistence semi-implicit finite difference technique which are confirmed stable. The response of the reactive fluid flow to variational increase in the values of some entrenched fluid parameters in the momentum and energy balance equations are obtained. A satisfying equations for the ratio of irreversibility, entropy generation and Bejan number are solved with the results presented graphically and discussed quantitatively. From the study, it was obtained that the thermal criticality conditions with the right combination of thermo-fluid parameters, the thermal runaway can be prevented. Also, the entropy generation can minimize at low dissipation rate and viscosity.

Effects of variable viscosity and temperature modulation on linear Rayleigh-Bénard convection in Newtonian dielectric liquid

The linear Rayleigh-Benard electro-convective stability of the Newtonian dielectric liquid is determined theoretically subject to the temperature modulation with time. A perturbation method is used to compute the critical Rayleigh number and the wave number. The critical Rayleigh number is calculated as a function of the frequency of modulation, the temperature-dependent variable viscosity, the electric field dependent variable viscosity, the Prandtl number, and the electric Rayleigh number. The effects of all three cases of modulations are established to delay or advance the onset of the convection process. In addition, how the effect of variable viscosity controls the onset of convection is studied.

The impact of variable fluid properties on hydromagnetic boundary layer and heat transfer flows over an exponentially stretching sheet

This paper put forward an analysis of variable fluid properties and their impact on hydromagnetic boundary and thermal layers in a quiescent fluid which is developed due to the exponentially stretching sheet. The viscous incompressible fluid has been set into motion due to aforementioned sheet. We assume that the viscosity and the thermal conductivity of the Newtonian fluid are temperature dependent. The governing boundary layer equations containing continuity, momentum and energy equations are coupled and nonlinear in nature, thereby, cannot be solvable easily by using analytical methods. Since the general boundary layer equations admits a similarity solutions, thus a generalized Howarth-Dorodnitsyn transformations have been exploited for the set-up of a coupled nonlinear ODEs. These transformed ODEs are solved numerically by a shooting method and is verified from MATLAB built-in collocation solver bvp4c for different parameters appearing in the work. We show results graphically and in a tabulated form for a constant and a variable fluid properties. We find that the temperature dependent variable viscosity and a thermal conductivity influence a velocity and a temperature profiles. We show that the thermal boundary layer decreases for constant variable fluid properties and increases for variable fluid properties

NUMERICAL ANALYSES ON THE PREDICTION OF NUSSELT NUMBERS FOR UPWARD AND DOWNWARD FLOWS OF WATER IN A SMOOTH PIPE: EFFECTS OF BUOYANCY AND PROPERTY VARIATIONS

This paper includes the Artificial Neural Network (ANN) solution as one of the numerical analyses to investigate the buoyancy and property variation effects calculating Nusselt numbers during the upward and downward flow of water in a smooth pipe. Available data in the literature (Parlatan et al.) has been used in the analyses to show ANN’s success ratio of predictability on the measured pipe length’s averaged Nusselt numbers (Nuavg) and forced convection’s Nusselt numbers (Nuo). Mixed convective flow conditions were valid for Reynolds numbers ranging from 4000 to 9000 with Bond numbers smaller than 1.3. Dimensionless values of Reynolds number, Grashof number, Prandtl number, Bond number, Darcy friction factor, isothermal friction factor in forced convection, ratio of dynamic viscosities, and a Parlatan et al.’s friction factor were the inputs while Nuavg and Nuo were the outputs of ANN analyses. All data was properly separated for test/training/validation processes. The ANNs performances were determined by way of relative error criteria with the practice of unknown test sets. As a result of analyses, outputs were predicted within the deviation of ±5% accurately, new correlations were proposed using the inputs, and importance of inputs on the outputs were emphasized according to dependency analyses showing the importance of buoyancy influence (GrT) and the effects of temperature-dependent viscosity variations under mixed convection conditions in aiding and opposing transition and turbulent flow of water in a test tube. 

Rheological analysis on non-Newtonian wire coating

In the present paper, wire coating process using viscoelastic non-Newtonian fluid is investigated along the effects of heat transfer, Joule heating and magnetohydrodynamic fluid flow. Temperature-dependent variable viscosity models are used. The boundary layer equations governing the flow and heat transfer phenomena are solved by applying powerful numerical technique. The notable aspect of the present study is to include porous matrix, which acts as an insulator to prevent heat loss. Similarly, the impact of heat generation is discussed because it controls heat transfer rates. The influence of non-Newtonian parameter, magnetic parameter, permeability parameter, heat generation/absorption parameter, etc. on wire coating is analyzed by graphs.