Thermophoretic Effects Research Articles

Convective thermal conditions and the thermophoretic effect's impacts on a hybrid nanofluid over a moving thin needle

AbstractThis research focuses on the heat source/sink, chemical reaction, and thermophoretic particle deposition in the influence of hybrid nanofluid over a moving thin needle subjected to a magnetic field. Using the appropriate transformations, a group of nonlinear partial differential equations may be converted to ordinary differential equations. Additionally, with the aid of computational software, the RKF‐45 approach is used for the numerical assessment, as well as the shooting operation. It should be mentioned that the results' approval demonstrates a strong association with the previous findings. The resulting graphs mainly explain the fundamental characteristics of hybrid nanofluids and nanofluids, as well as the consequences of different restrictions. An increase in needle size enhances the velocity profile, temperature profile, and concentration profile. The radial and axial velocity profiles are reduced when the magnetic constraint is increased, whereas the thermal and concentration patterns are reversed. Improved heat source‐sink as well as Biot number values will enhance the thermal profile. The concentration profiles will decrease due to reaction rate restrictions and thermophoretic limits. The inclusion of solid volume fraction reduces surface drag forces while increasing the rate of mass transfer. In most circumstances, hybrid nanofluid plays a prominent role than nanofluid.

Mathematical model of temperature-dependent flow of power-law nanofluid over a variable stretching Riga sheet

The present study explores the power law nanofluid flow over a variable Riga stretching sheet. The variable properties of thermal conductivity and viscosity under heat generation effects are explored in this analysis. Brownian motion, thermophoretic, and viscous dissipation effects are taken into account. The mathematical formulation in the form of partial differential equations is carried by boundary layer approximation. After applying the transformations, these differential equations are reduced into dimensionless ordinary differential equations. The dimensionless system is tackled through the ND solve method. The effect of involving parameters on the velocity, concentration, and temperature function is presented graphically while skin friction, Sherwood, and Nusselt numbers are described in terms of numerical data. Velocity profile shows a direct relation toward both variable viscosity and modified Hartmann number. The enhancement in variable thermal conductivity parameter, thermophoresis parameter, Eckert number, and heat generation parameter causes a significant rise in the temperature profiles, while the opposite is the case for Prandtl number. The concentration profiles expressed reduction by varying the Lewis number and Brownian motion parameter in the suction case, while it increased for an injection case. The concentration profile is observed increasing toward the thermophoresis parameter in the case of suction but it is reduced for the injection case.

Modelling convective transport of hybrid nanofluid in a lid driven square cavity with consideration of Brownian diffusion and thermophoresis

Previously, the homogenous models were predominant in hybrid nanofluid's studies. However, there is a serious deficiency in these models, that is, the heat transfer coefficients obtained by these models are inconsistent with the experimental results. To overcome this issue, we develop a novel hybrid nanofluid model based on the major slip mechanisms of nanofluids caused by Brownian diffusion and thermophoresis. The problem of flow and heat transfer of a hybrid nanofluid in a lid driven square cavity filled with porous medium is studied as an example to show the correctness and validity of this new model. Numerical results are given by means of the novel Coiflet wavelet homotopy analysis method in the terms of the Brownian motion and thermophoresis. The physical behaviors of hybrid nanofluids flow are discussed in terms of various quantities such as the stream-function, the isotherms, and the Nusselt and Sherwood numbers. The average Nusselt number evaluated with the help of the quadratic multiple regression analysis justifies that the thermophoretic effect is more dominant than the Brownian motion on Nusselt numbers at both walls.

Cubic autocatalysis-based activation energy and thermophoretic diffusion effects of steady micro-polar nano-fluid

Cubic autocatalysis-based activation energy and thermophoretic diffusion effects of steady micro-polar nano-fluid

Significance of magnetohydrodynamic Williamson Sutterby nanofluid due to a rotating cone with bioconvection and anisotropic slip

AbstractThe thermal transmission outcomes of Williamson Sutterby nanofluids owing to spinning cone with gyrotactic micro‐organisms such as self‐motivated microbes along with anisotropic slip conditions are probed in this article. The axi‐symmetric, unstable three‐dimensional stream of fluids is swayed by magnetic and buoyancy forces. Utilizing appropriate similarity variables, the leading partial differential formulation for velocity, temperature, concentration, and motile density of nanofluids are altered into nonlinear ordinary differential equations and these equations together with boundary constraints are resolved by computational code for Runga–Kutta method in MATLAB platform. A concise computational strategy is made by altering the inputs of influential factors. Nusselt number, Sherwood number, and motile density number are also computed and listed in tables. As the magnitudes of the slip parameters expand, the Nusselt number, and Sherwood number decline. The velocity along the x‐axis and the concentration variations amplify as the u‐velocity slip and solutal slip parameters are boosted. The temperature profile goes down for boosted values of A and . The fluids temperature distribution enhances directly with thermophoretic effect and Brownian motion of nano‐entities.

The role of temperature-induced effects generated by plasmonic nanostructures on particle delivery and manipulation: a review

Abstract Plasmonic optical tweezers that stem from the need to trap and manipulate ever smaller particles using non-invasive optical forces, have made significant contributions to precise particle motion control at the nanoscale. In addition to the optical forces, other effects have been explored for particle manipulation. For instance, the plasmonic heat delivery mechanism generates micro- and nanoscale optothermal hydrodynamic effects, such as natural fluid convection, Marangoni fluid convection and thermophoretic effects that influence the motion of a wide range of particles from dielectric to biomolecules. In this review, a discussion of optothermal effects generated by heated plasmonic nanostructures is presented with a specific focus on applications to optical trapping and particle manipulation. It provides a discussion on the existing challenges of optothermal mechanisms generated by plasmonic optical tweezers and comments on their future opportunities in life sciences.

Chemically reactive Maxwell nanoliquid flow by a stretching surface in the frames of Newtonian heating, nonlinear convection and radiative flux: Nanopolymer flow processing simulation

AbstractThe effects of a chemical reaction and radiative heat flux in a nonlinear mixed thermo-solutal convection flow of a viscoelastic nanoliquid from a stretchable surface are investigated theoretically. Newtonian heating is also considered. The upper-convected Maxwell (UCM) model is deployed to represent the non-Newtonian characteristics. The model also includes the influence of thermal radiation that is simulatedviaan algebraic flux model. Buongiorno’s two-component nanofluid model is implemented for thermophoretic and Brownian motion effects. Convective thermal and solutal boundary conditions are utilized to provide a more comprehensive evaluation of temperature and concentration distributions. Dimensionless equations are used to create the flow model by utilizing the appropriate parameters. The computed models are presented through a convergent homotopic analysis method (HAM) approach with the help of Mathematica-12 symbolic software. Authentication of HAM solutions with special cases from the literature is presented. The impact of various thermophysical, nanoscale and rheological parameters on transport characteristics is visualized graphically and interpreted in detail. Temperatures are strongly enhanced with Brownian motion and thermophoresis parameters. Velocity is boosted with the increment in the Deborah viscoelastic number and mixed convection parameter, and the hydrodynamic boundary layer thickness is reduced. A stronger generative chemical reaction enhances concentration magnitudes, whereas an increment in the destructive chemical reaction reduces them and also depletes the concentration boundary layer thickness. Temperature and concentration are also strongly modified by the conjugate thermal and solutal parameters. Greater radiative flux also enhances the thermal boundary layer thickness. Increasing the Schmidt number and the Brownian motion parameter diminish the concentration values, whereas they elevate the Sherwood number magnitudes,i.e.enhance the nanoparticle mass transfer rate to the wall.

MHD Mixed Convection Hybrid Nanofluids Flow over a Permeable Moving Inclined Flat Plate in the Presence of Thermophoretic and Radiative Heat Flux Effects

Recent nanotech advancements have created a tremendous platform for the development of a superior ultrahigh performance coolant referred to as nanofluid for several industrial and engineering technologies. In this research, the impact of thermophoretic and viscous dissipation on the radiative mixed convective flow comprising hybrid nanofluid through an inclined permeable moving flat plate with a magnetic field is examined numerically. A model of non-linear differential equations is derived based on some realistic assumptions and tackled numerically using the bvp4c technique. The impact of the specific set of distinguished parameters on the velocity profiles, shear stress, temperature distribution profiles, heat transfer, concentration distribution profile, and mass transfer for the two dissimilar branch solutions are discussed in detail. In addition, it has been discovered that double solutions exist in the case of an opposing flow, while a single solution is observed in the case of an assisting flow. The temperature distribution profile escalates with the radiation parameter, while decelerating the velocity and concentration profiles.

Thermo-solutal dual stratified convective magnetized fluid flow from an exponentially stretching Riga plate sensor surface with thermophoresis

A theoretical study is presented for the coupled thermo-solutal free convection two-dimensional boundary layer flow of a of a magnetized fluid from an exponentially stretched magnetic sensor (Riga plate) surface. Heat generation/absorption, nonlinear thermal radiation and thermophoretic body force effects are included. Furthermore, thermal and solutal stratification are also featured in the boundary layer model. The derived nonlinear partial differential equation system with associated wall (sensor surface) and free stream boundary conditions is transformed to system of ordinary differential equations (ODE) via applicable similarity variables. A numerical solution is developed with the efficient Runge–Kutta–Fehlberg (RKF) technique with a shooting numerical method, in MATLAB software using the RKF-45 method. The graphical profiles were represented to examine the impacts of physically parameterics on the important physical stream features. Streamline and isotherm plots are also included for thermal buoyancy effect (Grashof number).Validation of solutions with earlier simpler models is included. A relatively well agreement is achived between model prediction and the benchmark value. Values for skin friction factor, Nusselt number and Sherwood numbers are also tabulated to quantify momentum, heat and mass (species) transfer characteristics at the sensor surface. The results indicate that the significant depletion in temperature accompanies accumulation in magnetization and thermal stratification parameters. Significant accumulation in mixed convection and Riga plate electrode width parameter enhance the concatenation profiles. Nusselt number grows substantially as thermal stratification and radiative parameter increases. Sherwood number grows substantially as solutal stratification, thermophoresis and Schmidt parameter increases. The present study generalizes previous models to include simultaneously exponential stretching, thermophoresis, thermal and solutal (mass) stratification and heat source/sink effects.

Heat transfer enhancement of Fe 3 O 4 ‐water nanofluid by the thermo‐magnetic convection and thermophorestic effect

The promotion of the heat transfer by ferro-nanofluid under a magnetic field has caught more extensive attention in the field of nuclear industry and energy engineering. Firstly, a modified model based on the Buongiorno model was proposed to investigate the heat transfer considering the Kelvin force in the presence of an inhomogeneous magnetic field to elevate the heat transfer performance of nanofluid using thermomagnetic convection. Secondly, the influence of Kelvin force, thermophoresis, and Brownian motion of nanoparticles on the heat transfer at a moderate Reynolds number was investigated. The numerical results indicate that the chaotic convection induced by the Kelvin force and the thermophoretic effect are much important factors. Thirdly, the numerical results demonstrate that the NSN and NSN/SNS arrangements of magnets should be the preferential selection. Besides, the more powerful magnetic field and greater volume fraction of nanoparticle can produce better heat transfer performance. Finally, the discussions on the underneath mechanisms for heat transfer augment are conducted, and it can be concluded the thermomagnetic convection induced the combination of the magnetic effect and thermophoretic effect may be the key mechanism.

Thermophoresis in a time‐dependent free convection flow with suspended particles in a chamber having thermal Robin boundary conditions

AbstractThis study presents a numerical analysis of a model for the coupled mechanisms of transport of natural convection, thermophoresis, and double‐diffusive heat and mass transfer of a fluid holding suspended particles in an infinite parallel‐plated channel. The governing equations in an unsteady state are nondimensionalized and solved by subdivisions of the finite difference method. The simulations of the numerical algorithms are verified by analytic results. Thermal and mass transfer characteristics of parameters like time are displayed graphically. The findings in this study suggest that increases in Schmidt number accentuate the effect of thermophoresis hence is the effective thermophoretic coefficient agreeing with Magyari. At steady‐state, there is an increase in skin friction at the hot wall when the thermophoretic coefficient was in the range , alerting when the walls of the channel are in danger from the heat. The gradient of concentration of particles at the hot wall, when in steady‐state remains unity for every value of thermophoretic coefficient and at the cold wall is constantly . This study suggests that the steadiness of a fluid and conduction/convection resistances within and outside boundaries may influence thermophoretic effect. This study offers possibilities and supports the developments in thermophoretic cells used in the manipulation of particles for biochemical and medical research.

Two-phase model of intravenous magnetic nanoparticle hyperthermia in muscle and prostate tumours

In this work, we investigate heat transfer phenomena in muscle and prostate tissues during magnetic hyperthermia cancer therapy with intravenously-injected maghemite nanoparticles. The resulting suspension of nanoparticles in blood is considered to be a non-Newtonian nanofluid, and a two-phase model that considers Brownian and thermophoretic effects is considered. The geometrical domain is comprised of a blood vessel region, cancerous and non-cancerous (prostate or muscle) tissue regions, and a region of fat tissue. The mixed finite element technique is utilized for solving the governing equations and their associated initial and boundary conditions; triangular quadratic elements are chosen for the temperature, velocity and nanoparticle volume fraction approximations, whereas triangular linear elements are selected for the pressure approximation. Based on this numerical solution, we examine the impact of the nanoparticle volume fraction at the inlet of the blood and magnetic field oscillation frequency on heat transfer and nanoparticle transport. The findings of this study indicate that in the prostate and muscle tissue cases, the nanoparticle distribution non-uniformity and the tissue and blood vessel temperatures are increased, and the average pressure is reduced, by increasing the inlet nanoparticle concentration and magnetic field oscillation frequency. In the muscle tissue case, the mean flow velocity can be increased by increasing the inlet nanoparticle concentration and decreasing the magnetic field oscillation frequency. Based on these findings, recommendations are made for improving the effectiveness of magnetic nanoparticle hyperthermia in cancerous muscle and prostate tissues. The research conducted in this work is motivated by the need for a better understanding of the factors impacting nanoparticle transport in tissues and heat generation during magnetic hyperthermia. Using the mathematical model developed herein, tissue temperatures attained under intravenous magnetic hyperthermia treatment can be accurately predicted.

Energy and mass transfer analysis of 3-D boundary-layer flow over a rotating disk with Brownian motion and thermo-phoretic effects

The advancement of nanofluid technology has become an essential tool for investigating thermal conductivity enhancement, which is highly valuable for industrial and engineering applications in many fields including mathematics, physics, engineering, and materials science. This analysis focuses on 3-D boundary-layer flow on nanofluid over a rotating disk by incorporating chemical reaction and thermal radiations effects. One aim of this article is to analyze the energy and mass transport rates for nanofluids. In this study, the Brownian motion and thermophoretic impacts are considered. The governing flow equations are converted to ODE via suitable similarity transformations. The resulting equations were solved via well know technique Keller box method. This analysis revealed that the azimuthal and axial velocities show an inverse pattern against the various values of index factor, n, although the radial velocity has the highest value and decreases significantly. The behavior of the von Karman flow is also recovered for setting the index factor (n = 1). Moreover, it is found that the temperature of nano liquid increases by increasing the Brownian motion and thermophoretic factors.

RETRACTED: Thermal and chemically reactive features of Casson nanofluid flow with thermophoresis and Brownian effect over an exponentially stretching surface

Heat and mass transfer of the MHD flow of Casson nanofluid by an exponential stretching sheet discussed in this analysis. The MHD with joule heating effects for Casson nanofluid numerically investigated. To characterize the transport property of heat and mass, we considered the thermophoresis and Brownian effect along with thermal radiation and thermophoretic effects. Additionally, we consider the microorganism theory to analyze the suspended nanoparticles by bio-convection. The mathematical model developed on the base of boundary layer flow of casson nanofluid at exponentially stretching surface in term of partial differential equations. The partial differential equations are transformed into nonlinear ordinary differential equations by means of similarity variable transformations. The non-dimensionalized differential equations have numerically tackled by using the Bvp4c MATLAB technique. The graphical outcomes are obtained against the various parameters. Moreover, physical quantities are examined graphically and tabulating data. It is reviewed that resistance of fluid flow improves by the higher estimation of the Casson fluid parameter. Therefore, the axial and transverse velocities are reduced. Further, it is noticed from the tabulated data that more vital values of the Casson fluid parameter diminishes the skin friction and mass transfer rate but enhances the heat transfer rate.

Impact of Joule heating and multiple slips on a Maxwell nanofluid flow past a slendering surface

This manuscript presents a study of three-dimensional magnetohydrodynamic Maxwell nanofluid flow across a slendering stretched surface with Joule heating. The impact of binary chemical reactions, heat generation, thermal radiation, and thermophoretic effect is also taken into consideration. The multiple slip boundary conditions are utilized at the boundary of the surface. The appropriate similarity variable is used to transfer the flow modeled equations into ODEs, which are numerically solved by the utilization of the MATLAB bvp4c algorithm. The involved parameter’s impact on the concentration, velocity, and temperature distribution are scrutinized with graphs. The transport rates (mass, heat) are also investigated using the same variables, with the results reported in tabulated form. It is seen that the fluid relaxation, magnetic, and wall thickness characteristics diminish the velocities of fluid. Further, the velocity, concentration, and temperature slip parameters reduce the velocities of fluid, temperature, and concentration distribution. The results are compared to existing studies and shown to be in dependable agreement.

Characteristic of thermophoretic effect and convective thermal conditions on flow of hybrid nanofluid over a moving thin needle

This paper presents the impact of thermophoretic particle deposition in the flow of a hybrid nanofluid (Fe3O4-Go/H2O) over a moving thin needle in the presence of a convective boundary condition. The set of non-linear partial differential equations is transformed into ordinary differential equations with the implementation of suitable transformations. Further, the numerical evaluation is carried out by employing the RKF-45 method along with the shooting procedure via the aid of Maple 17 software. It should be noted that the approval of the results shows a good correlation with the existing results. The obtained graphs mainly explain the fundamental characteristics and impacts of different constraints on hybrid nanofluid and mano nanofluid. The main outcomes bring out that enhancement of thermophoretic parameter increases the concentration field and increase in Biot number increases thermal efficiency. Also, the velocity and concentration profiles of hybrid nanofluid reduce with the increment of the magnetic parameter. But the thermal profile of hybrid nanofluid exhibits contrasting behavior.

Influence of the induced magnetic field on second-grade nanofluid flow with multiple slip boundary conditions

The present research focuses on the MHD second-grade nanofluid flow with induced magnetic field and viscous dissipation over an exponentially stretching surface. The solutal and thermal energy equations are analyzed in the presence of thermophoretic effect and variable thermal conductivity. The solutal and thermal slip boundary conditions are imposed on the surface of the sheet. In the mathematical modeling, the Brownian motion, and thermophoresis consequences are also discussed. The physical appearance of the induced magnetic field on the second-grade nanofluid is the central aim of this investigation. The mathematical flow model which is in the form of nonlinear PDEs is transformed into the system of couple ODEs by the usage of suitable similarity variables. These couple equations are tackled numerically with the help Bvp4c Matlab approach. The illustration of parameters on the flow model is discussed via graphs and tables. It is noted that the induced magnetic field profile and velocity of fluid intensify for the stronger values of second-grade parameter. Further, the numerical result shows that skin friction rate boosts via greater estimation of second-grade parameter and it reduces for magnetic Prandtl number.

The collective motion of thermophoretic-type active particle suspension under spatial–temporal modulation

The mesoscopic collective behavior of a thermophoretic-type active particle suspension under a spatial–temporal modulated excitation field is experimentally studied. By using a digital light processing chip, a sinusoidal-like spatial–temporal varying laser pattern (intensity wave) is projected on the particle suspension to modulate the particle propulsion strength through the thermophoretic effect and to exert spatial confinement through the optical trapping effect. For static and slow (wave speed ≪ particle propulsion speed) modulations, in contrast to the passive particles trapped around the wave crest, the self-propulsion strength splits the particle distribution into two branches adjacent to the edges of confinement similar to the bacteria system, and the profile of particle distribution moves coherently with the modulation wave. Once the wave speed increases to the order of the particle propulsion speed, the splitting of particle distribution disappears. Furthermore, it is remarkable that the forward propagating modulation-induced certain fraction of backward streaming particles are observed. This is a generic behavior of a self-propelling active particle suspension, which is not found in the bacteria system. This finding should be useful for particle manipulation at the mesoscopic scale.

Brownian motion and thermophoretic diffusion effects on the dynamics of MHD upper convected maxwell nanofluid flow past a vertical surface

The suspension of nanoparticles in the base fluid has been tested to improve the heat transfer properties of the fluid since solid metals are characterized with higher thermal conductivity than the convectional working fluid. This present work focuses on the suspension of nanoparticles into the upper convected Maxwell fluid model (UCM) so as to improve the heat transfer efficacy of the fluid. The governing partial differential equations and their related boundary conditions are transformed and parameterized by applying appropriate transformations into a system of non-linear ordinary differential equations and the series solutions are obtained through homotopy analysis method. The impact of various parameters on velocity, temperature and nanoparticles concentration profiles are reviewed and discussed. It is discovered that increasing the Brownian motion increases the thermal conductivity of fluid and hence promotes the effective movement of the nanoparticles.

Entropy analysis of unsteady MHD three‐dimensional flow of Williamson nanofluid over a convectively heated stretching sheet

AbstractThis article addresses an investigation of the entropy analysis of Williamson nanofluid flow in the presence of gyrotactic microorganisms by considering variable viscosity and thermal conductivity over a convectively heated bidirectionally stretchable surface. Heat and mass transfer phenomena have been incorporated by taking into account the thermal radiation, heat source or sink, viscous dissipation, Brownian motion, and thermophoretic effects. The representing equations are nonlinear coupled partial differential equations and these equations are shaped into a set of ordinary differential equations via a suitable similarity transformation. The arising set of ordinary differential equations was then worked out by adopting a well‐known scheme, namely the shooting method along with the Runge‐Kutta‐Felberge integration technique. The effects of flow and heat transfer controlling parameters on the solution variables are depicted and analyzed through the graphical presentation. The survey finds that magnifying viscosity parameter, Weissenberg number representing the non‐Newtonian Williamson parameter cause to retard the velocity field in both the directions and thermal conductivity parameter causes to reduce fluid temperature. The study also recognizes that enhancing magnetic parameters and thermal conductivity parameters slow down the heat transfer rate. The entropy production of the system is estimated through the Bejan number. It is noticeable that the Bejan number is eminently dependent on the heat generation parameter, thermal radiation parameter, viscosity parameter, thermal conductivity parameter, and Biot number. The skillful accomplishment of the present heat and mass transfer system is achieved through the exteriorized choice of the pertinent parameters.