Mixed Convection Research Articles

Bioconvective magnetized flow analysis of a tangent hyperbolic nanofluid with nonuniform source/sink over an exponentially porous stretching sheet

AbstractThis study use numerical method to investigate the transportation of a bioconvective magnetized tangent hyperbolic nanofluid across an exponentially porous stretched sheet. The flow model takes into account the important contributions of Joule heating, thermal radiation, activation energy, and nonuniform heat source/sink. Moreover, slip boundary conditions with gyrotactic microorganisms are taken into flow analysis. The flow model is converted into a system of nonlinear ordinary differential equations (ODEs) using suitable similarity variables. The bvp4c approach in MATLAB is used to get numerical solutions for this system. The study evaluates the influence of different parameters on the velocity, temperature, concentration, and microorganism profile via graphical representations. The results indicate that increasing the mixed convection parameters accelerates the velocity profile, whereas raising the magnetic parameter slows it down. The temperature profile increases with higher values of radiation parameter, however, it decreases as the Prandtl number and thermal slip parameter increase. Furthermore, the microorganism profile decreases as the bioconvection Lewis number and microorganism slip parameter increase.

Impact of Reynolds and Prandtl Numbers Coupled with Viscous Dissipation on Mixed Convection in A Square Cavity

Efficient thermal management in industrial manufacturing and electronic cooling systems can be achieved by comprehending characteristics of Reynolds and Prandtl numbers in mixed convection scenarios, which aids in the optimization of heat transfer systems through the utilization of forced and natural convection effects. The impact of Reynolds and Prandtl numbers on mixed convection in a square cavity connected to a moving heated horizontal plate is investigated in this research paper. The convective behavior under different conditions was evaluated by discretizing the flow governing equations, which included the momentum and energy equations, using the finite difference method. The research assessed various fluids, including air (Pr = 0.7), liquid metal (Pr = 0.01), and oil (Pr = 10). The Reynolds number ranged from 0.001 to 100, the Eckert number ranged from 0.01 to 40, and a constant Richardson number (Ri = 1) was maintained throughout. The results revealed that the Reynolds number substantially impacts the velocity and temperature characteristics, especially when coupled with a Prandtl number over one and when viscous dissipation remains constant. The utmost velocity that can be attained within the cavity is significantly diminished as the Reynolds number rises, underscoring the critical importance of dynamic fluid properties in determining heat transfer efficiency and fluid flow characteristics. The research unveiled the critical importance of Reynolds and Prandtl numbers in the field of fluid dynamics concerning enhancing heat transfer attributes for engineering purposes, thereby guaranteeing the effectiveness of thermal systems.

Bioconvective magnetohydrodynamic flow of tangent hyperbolic nanofluid across a stretched surface, with Arrhenius activation and convective heat and slip conditions

The current study investigates mixed convective flow of an unsteady MHD tangent hyperbolic nanofluid due to a stretching surface with motile microorganisms via convective heat transfer and slip conditions. The flow analysis's governing equations were converted into a nondimensional relation by using the proper alteration. The pertinent similarity transformations are utilized in the main equations, and the solutions are obtained using the integrated bvp4c software. A good agreement with previously published data indicates the efficacy of the numerical technique. The following are the main findings: increasing the magnitude of the radiation and mixed convection parameters improves the velocity profile, whereas the Weissenberg number and magnetic field demonstrate the opposite influence; improvements in heat transfer occur due to the thermal radiation parameter, Brownian movement, and thermophoretic effects; activation energy improves concentration profile, whereas Lewis number shows opposite effect; bioconvection Lewis number and Peclet number declines the Motile microorganism density. Additionally, a tabular analysis of the skin friction, motile microorganism density, Nusselt number, and Sherwood number is also provided.

ANALYTICAL STUDY ON FULLY DEVELOPED MIXED CONVECTION COUETTE FLOW IN A VERTICAL CHANNEL WITH VISCOUS DISSIPATION EFFECT

The study of mixed convection flow in a vertical channel with viscous dissipation has been examined. To solve the governing energy and momentum equations, the Homotopy perturbation method was employed. Graphs were generated to analyze the impact of the governing flow parameters. Numerical values for skin friction, rate of heat transfer, and mass flux were estimated. The study revealed that an increase in mixed convection expands the reverse flow region and raises the critical value of mixed convection that leads to flow reversal. Additionally, both fluid temperature and velocity rise with increased viscous dissipation, as higher viscous dissipative heat elevates temperature, subsequently increasing the buoyancy force.

Numerical heat transfer analysis of Carreau nanofluid flow over curved stretched surface with nonlinear effects and viscous dissipation

The article presents a comprehensive study that thoroughly assesses the effects of Carreau fluid flow over a curved stretch surface. The study meticulously considers various factors, including nonlinear thermal radiation, convective boundary conditions, viscous dissipation, thermophoresis, Brownian motion, and nonlinear mixed convection. By using similarity variables, the problem's governing equations are transformed from nonlinear partial differential equations to nonlinear ordinary differential equations, and then the shooting method is applied to obtain the results. The study also rigorously examines the effect of modifying flow factors on velocity, temperature, and concentration in shear-thickening situations through graphical assessment. Furthermore, according to the corresponding values, a table is provided with data on skin friction, Nusselt, and Sherwood numbers. This study offers new perspectives on the complex mechanisms of Carreau fluids flowing over curved surfaces, with potential applications in materials engineering and fluid mechanics.

Thermal management of mixed convection in a partially heated triangular cavity with a cylindrical enclosure

Abstract Numerical Investigations are carried out to study the thermal performance of the magnetohydrodynamics laminar mixed convection in a triangular cavity with a circular enclosure. The present work analysis is carried out on a triangular cavity with circular blockage by varying the Re (200-600), Ri (0.01-1), and Gr (4000-36000), respectively. The working system is a triangular cavity filled with water with a circular block. Non-linear partial differential equations are the governing equations that use the finite element method. The moving upper wall and temperature difference contribute to the convection heat transfer. The upper wall is heated and maintained at high temperatures. The other walls are kept as adiabatic. The obstacle at the center is kept at a low temperature. The physical parameters are non-dimensional numbers like the Reynolds, Richardson, and Hartmann numbers that influence the heat transfer rate. The Richardson and Reynolds numbers impact positively, and the Hartmann numbers tend to decrease heat transfer rates.

Assisting and opposing mixed convective flow over a solid sphere at its bottom stagnation point with a constant surface heat, mass and motile microorganism flux

This study examined the laminar mixed convective flow around the lower point of stagnation for a solid sphere with a steady flux of gyrotactic microbial motility, mass and temperature. Biological convection phenomena have been considered in this study due to their intermixing traits and capacity in order to enhance mass transit in numerous biotechnology and biological systems. The first objective of this study is to examine and establish the mathematical formulation comprising partial differential equations for energy, momentum, mass conservation and mobile microorganism conservation balances. To do numerical calculations, the controlling partial differential equations are initially transformed by similarity transformations into a collection of interconnected non-linear ordinary differential equations. These equations are then solved by using the MATLAB Bvp4c scheme. The results indicate that several controlling parameters, particularly bioconvection parameters such as the Lewis number ( Le ), Bioconvection Lewis parameter ( Lb ) and Bioconvection Peclet number ( Pe ), have significant effects on flow transfer rates. A dual solution is observed in a certain region of mixed convection λ , where the mixed convection parameter is within the range of 0.41–0.65. The findings reveal significant results from dual solution analysis, highlighting the occurrence of unstable and stable phenomena for specific values of bioconvection parameters exclusively in the case of opposing flow. The assisting flow demonstrates only a single solution that is physically stable and unique. Observing lower stagnation point flow is essential for predicting and analysing complex fluid–microorganism interactions in various scientific and engineering applications such as designing spherical-shaped microbial fuel cell. Optimising flow conditions can enhance the efficiency of processes like wastewater treatment, where microorganisms play a crucial role in breaking down pollutants.

Numerical study on natural, forced and mixed convection of a hybrid photovoltaic inverter

Numerical study on natural, forced and mixed convection of a hybrid photovoltaic inverter

Significance of gyrotactic microorganism's analysis for magnetized convectively heat 3D Sisko fluid flow with bioconvection phenomenon

In this research article, the bioconvection of oxytactic microorganisms with magneto-hydrodynamic (MHD) 3D steady flow of Sisko nanomaterial over a stretching sheet through convective conditions is deliberated and analyzed. Possessions of thermophoresis, Brownian motion as well as mixed convection in the Sisko fluid are also deliberated. Sisko fluid is supposed to be electrically conducted over and done with a constant pragmatic magnetic field. The flow problem is communicated using governing relations and problem is transmuted into dimensionless form among non-similar procedure. To obtain convergent solutions we must solve nonlinear differential systems. The consequences of several physical parameters have been deliberate and discussed. Our results displayed that the higher microorganism difference parameter condensed the microorganism profile, while an opposite influence is established for magnetic parameter. Concentration proises of the Sisko fluid flow are improved by growing Biot number whereas contracted beside the Lewis number. In recent years, the scientists have shown great attention in the field of bioconvection owing to its countless applications such as amassing the cells, bioreactors, gas-bearing sedimentary, modeling oil, exclusion of living, and nonliving cells, and lots of additional.

Dual characteristics of mixed convection flow of three-particle aqueous nanofluid upon a shrinking porous plate

Purpose This study aims to analyze the thermo-hydrodynamic characteristics for the mixed convection boundary layer flow of three-particle aqueous nanofluid on a shrinking porous plate with the influences of thermal radiation and magnetic field. Design/methodology/approach The basic equations have been normalized with the help of similarity transformations. The obtained equations have been solved numerically using the shooting method in conjunction with the sixth-order Runge–Kutta technique. Numerical results for the velocity and temperature are illustrated with varying relevant parameters. Findings The results reveal that the local drag coefficient increases with higher values of the magnetic field parameter, nanoparticle volume fraction and suction parameter. On the other hand, boosting the radiation parameter and nanoparticle concentration notably enhances heat transfer. Furthermore, it is noted that the suction parameter and magnetic field parameter both lead to an increase in velocity and promote the occurrence of dual solutions within the problem conditions. Research limitations/implications The limitations are that the model is appropriate for thermal equilibrium of base fluid and nanoparticles, and constant thermo-physical properties. Originality/value To the best of the authors' knowledge, no study has taken an attempt to predict the flow and heat transfer characteristics of unsteady mixed convection ternary hybrid nanofluid flow over a shrinking sheet, particularly under the influence of magnetic field and radiation. The findings obtained here may hold particular significance for those interested in the underlying theoretical and practical implications.

Significance of mixed convection and heat transfer flow past a vertical Riga plate in the presence of alumina nanoparticles: Analysis of streamlines for oblique stagnation point

AbstractThe aim of the current study to inspect the magnetic flow properties and heat transport features near an oblique stagnation point of a nanofluid with mixed convection through a vertical Riga plate are examined. The Riga plate is a familiar actuator made out of permanently fixed electrodes and magnets that moved away from the plate due to an exponential decline in the Lorentz force. Nanofluid is taken into consideration due to its peculiar properties, such as remarkable thermal conductivity is the significance of the study. These properties are important in heat exchangers, electronics, advanced nanotechnology, and material sciences. Using usual similarity transformations, the group of leading partial differential equations is distorted into a group of nonlinear ordinary differential equations. Then, a very proficient procedure namely bvp4c is utilized to discover the solution. For particular values of the different influential fluid parameters, the characteristics of the dimensionless temperature and velocity along with drag force and heat transfer are investigated graphically. In addition, the symmetrical results were initiated for both cases of the slip and without slip parameters. It is demonstrated that for greater influence of the volume fraction of nanoparticles, the normal and tangential velocity profile drops down for the instances of aiding and opposing flows due to fluctuations in the presence of slip factor, and absence of slip factor. In contrast, the temperature profile intensifies in both the cases of slip parameters and without the slip parameter owing to the phenomenon of assisting flow and opposing flow subject to superior impressions of the nanoparticle volume fractions. It is also observed that depending on the equilibrium between buoyancy effects, obliqueness, velocity slip parameters, and straining motion, the location of the point of zero shear stress (friction factor on the surface of the wall) is displaced to the right or the left of the origin.

Magnetic field effects on double-diffusive mixed convection and entropy generation in a cam-shaped enclosure

This study investigates double-diffusive mixed convection and entropy generation under magnetic influence within a novel cam-shaped enclosure, with applications in automotive engineering. The unique geometry creates distinct flow patterns that enhance heat and mass transport. Using the Galerkin finite element method, we analyzed the effects of key parameters, including buoyancy ratio, Reynolds number, Hartmann number, magnetic field inclination angle on average Nusselt and Sherwood numbers, and total entropy generation. Results show that increasing the buoyancy ratio and Reynolds number enhances heat transfer, while the Hartmann number significantly impacts flow characteristics and entropy generation. The magnetic field inclination angle exhibits a non-linear effect on heat transfer and entropy production. These findings provide valuable insights for optimizing heat transfer systems in complex automotive geometries.

Effect of thermal radiation and inclined magnetic field on thermosolutal mixed convection in a partially active wavy trapezoidal enclosure filled with hybrid nanofluid

This work focuses on the examination of the magneto-thermosolutal convection in a lid-driven wavy trapezoidal enclosure in the presence of thermal radiation. The wavy cavity is filled with radiative Fe3O4-Cu-H2O hybrid nanoliquid. In this work, two cases are considered depending on the location of heat and concentration sources. A portion of the vertical walls are kept hot and in high concentration while the remaining parts are in adiabatic condition. The adiabatic flat upper lid is moving towards the right with equal speed. In addition, the lower wavy border is cold and low concentration. The governing Navier–Stokes equations are modeled to describe thermosolutal phenomena within the wavy enclosure. These equations are solved by reconstructing a recently developed compact scheme. Computed outcomes are presented in terms of streamlines, isotherms, iso-concentrations, average Nusselt and Sherwood numbers to evoke the thermosolutal phenomena for various physical parameters. Also, computing in-house code is validated with the published numerical and experimental and literatures. This investigation surveys the roles of several well-defined parameters such as Richardson number (Ri), Lewis number (Le), Buoyancy ratio number (N), Radiation parameter (Rd), Hartmann number (Ha), inclination of angle (γ), undulation of the wavy surface (d) and solid volume fraction (ϕhnp) of the hybrid nanofluid. An increase in the Lewis number (Le) enhances species diffusion within the system but diminishes thermal transport. This work reveal that a change in ϕhnp from 0% to 4%, heat transfer is upgraded up to 4.28% in Case I and 3.93% in Case II while mass transfer is declined by 2.24% in Case I and 1.60% in Case II. Results indicate that Case I performed better than Case II in the case of energy and solutal transfer. This work has many practical applications such as heat exchangers, electronic device cooling, food processing and porous industrial processes.

A computational study of Eyring‐Powell fluid model over a rotating cone with magnetic field and joule heating effect

AbstractIn this research, we investigate mixed convection transport of mass and heat transfer in the unsteady boundary layer flow of the Eyring‐Powell fluid around a rotating cone in the presence of Brownian and thermophoresis effects. Rotating cones are widely used in conical diffusers, medical devices, Aerospace Engineering and a variety of rheometric and viscosimetry applications. Specifically, we focus on the flow of the Eyring‐Powell fluid around the cone in the presence of magnetohydrodynamics and nanofluid. The modeled momentum, energy, and concentration equations of the problem are transformed into nonlinear dimensionless, nonlinear ordinary equations by utilizing the similarity variables. These nonlinear coupled ordinary differential equations are solved numerically via Bvp4c, and the outcomes for important physical parameters on momentum, energy, and concentration equations are presented graphically. The computational outcomes of physical parameters for skin friction coefficient, local Nusselt number, and Sherwood are also presented in tabular form.

Impact of cold block shapes on heat transfer and mixed convection in a ventilated square cavity with Ag/water nanofluid

This study investigates mixed convection in a ventilated square cavity filled with an Ag/water nanofluid, containing central cold blocks of various shapes (square, circle, triangle, and ellipse). The goal is to understand the impact of nanoparticle concentration and the geometric shapes of the blocks on heat transfer. In the cavity, the inlet is located in the upper left corner, while the outlet is positioned in the lower right corner. Mixed convection is induced by cooling at the inlet of the ventilated cavity and uniform heating of its lower wall. The equations governing the flow of an incompressible Newtonian nanofluid are assumed to be two-dimensional, stable, and laminar. The finite volume method is used for numerical simulations. The effect of four different geometric shapes of the cold obstacle (circular, square, triangular, and elliptical) on fluid flow and heat transfer rate is also explored. The results show that increasing the nanoparticle concentration enhances heat transfer within the cavity. This improvement is particularly notable when the central cold obstacle takes on a circular shape, leading to better mixed convection and a higher heat transfer rate. The square and triangular shapes yield similar, albeit slightly lower, results, while the elliptical shape is the least effective for heat transfer.

Heat transfer characteristics of mixed convection inside a differentially heated square cavity containing an oscillating porous cylinder

The current study presents mixed convective flow inside a square chamber holding a centrally placed and thermally conductive oscillating porous circular cylinder. The left boundary's temperature is kept larger than that of the right edge, and the horizontal edges are preserved at adiabatic settings. The circumferential speed of the cylinder is sinusoidal and oscillating in nature. The fluid region within the chamber is modeled employing 2D Navier-Stokes and heat energy equations. Furthermore, the fluid circulation and heat transmission within the porous cylinder are modeled using the Darcy-Brinkman-Forchheimer formulation. The leading equations are discretized utilizing the Galerkin finite element technique. The parametric study is undertaken considering three distinct diameters of the porous cylinder and three distinct oscillation frequencies. The instant Nusselt number is evaluated along the heated wall, which varies in an oscillatory pattern owing to the repeated contraction and enlargement of the thermal boundary layer. The Nusselt number is averaged over time once the value becomes statistically stationary. The study is conducted within a mixed convection region with Reynolds (Re = 100), Richardson (0.1 ≤ Ri ≤ 10), and Grashof (103 ≤ Gr ≤ 105) numbers. Upon thorough examination, it becomes clear that the system's thermal performance shows promising improvement with the largest cylinder diameter and the lowest oscillation frequency. Specifically, the average Nusselt number shows a maximum improvement of 21.50 % at the largest cylinder diameter.

Cattaneo-Christov fluxes for nonlinear mixed convective entropy generated Reiner-Rivlin material flow

Thermal and solutal transportation processes involve in tremendous useful applications related to heat exchanger, scientific, micro-electronic device technologies and industry sectors like nuclear reactors cooling, marine engineering, nanotechnology, thin-film technology, biomedical applications and thermal conduction in soft tissue. In view of such useful applications the Cattaneo-Christov analysis for nonlinear mixed convective Reiner-Rivlin material flow in presence of constant applied magnetic field is considered. Heat source, magnetohydrodynamics and radiation are incorporated in energy equation. Cattaneo-Christov flux is employed to discuss the thermal and mass transport characteristics. Entropy calculation in radiating flow is discussed. The proposed non-linear systems are transformed into dimensionless ordinary systems through appropriate transformation. Non-linear ordinary expressions are computed for convergent series solutions through Optimal homotopy analysis technique (OHAM). Graphical interpretations for quantities under interest against pertinent variables are explored. Large magnetic parameter has opposite impact for entropy and fluid flow. An increase of temperature through thermal relaxation time parameter is noticed. Velocity has same trend for both mixed convection and Reiner-Rivlin fluid variables. Reduction in concentration is seen for solutal relaxation time parameter. Temperature enhancement is witnessed in presence of heat generation. Entropy rate enhancement for radiation is observed. Decrease in concentration is noticed for reaction. Entropy rate increases against diffusion variable is enhanced.

Dynamics of heat transfer in complex fluid systems: Comparative analysis of Jeffrey, Williamson and Maxwell fluids with chemical reactions and mixed convection

This study addresses the complex dynamics of heat transfer in magnetohydrodynamic (MHD) systems involving Jeffrey, Williamson, Maxwell, and Newtonian fluids, focusing on how chemical reactions, activation energy, porosity, and mixed convection impact fluid behavior. The problem is critical due to the significant influence these factors have on industrial processes and applications involving non-Newtonian fluids. The developed a mathematical model represented by partial differential equations (PDEs), which were solved using similarity transformations and the fourth order Runge-Kutta (R-K) method combined with shooting technique, with MATLAB software facilitating the solution process. The results reveal that variations in magnetic field strength, porosity, and buoyancy force significantly affect fluid velocities, while radiation, Brownian motion, and thermophoresis alter temperature profiles. Furthermore, chemical reaction rates, Schmidt number, relaxation constant, and activation energy influence fluid concentrations. Key findings include that increasing porosity and magnetic field strength generally decreases fluid velocity, while higher radiation and Prandtl numbers reduce temperature. Chemical reactions and activation energy decrease fluid concentrations, with non-Newtonian fluids showing more pronounced effects compared to Newtonian fluids. The novelty of this work lies in its comprehensive analysis of multiple interacting parameters and their combined effects on heat transfer in MHD systems, providing insights that extend beyond previous studies in the literature. This research offers valuable implications for optimizing fluid dynamics in various industrial applications, including food processing, ink formulation, and friction reduction.

Synergistic effects of magnetic fields and Y-obstacles on a nanofluid-based split lid-driven thermal system

This study investigates the complex hydrothermal behavior in a novel split-driven square cavity filled with CuO-water nanofluid and featuring a Y-shaped obstacle. The research explores the interplay among mixed convection, magnetohydrodynamics (MHD), and geometric factors in a previously unexamined configuration. The upper wall is split into two isothermally heated, translating sections, while the bottom wall and Y-shaped obstacle provide cooling boundaries. Using finite element analysis, we examine the effects of Reynolds number (Re = 10-200), Rayleigh number (Ra = 103-106), Hartmann number (Ha = 0-70), and magnetic field inclination (λ = 0-150°) on flow patterns, heat transfer, and entropy generation. Energy flux vectors are utilized to analyze thermal energy transport dynamics. Key findings are as follows. (1) Increasing Re enhances fluid mixing, resulting in up to a 65% increase in the average Nusselt number (Nu). (2) Nu peaks at Ra ≈ 105, then slightly decreases due to complex force interactions. (3) Increasing Ha suppresses convection, reducing Nu by up to 30%. (4) Optimal heat transfer occurs at λ ≈ 75°. (5) The Y-shaped obstacle enhances heat transfer by up to 30%. These results provide insights for optimizing thermal management in applications requiring precise temperature control, potentially improving energy efficiency in advanced heat transfer systems.

Numerical Approach of the First Instability Appearance in Inclined Taylor–Couette System

The present study numerically investigates the three-dimensional forced and mixed convection heat transfer in an inclined Taylor–Couette system (η=0.5 and Γ=20) submitted to a radial temperature gradient. The main objective of this study is to determine the effect of the angle inclination duct on the thermal and dynamic fields. Several cases have been dealt with depending on the inclination angle to detect the critical Reynolds number in each case. The model of the conservation equations with their boundary conditions is numerically solved by the finite volume method with a second-order spatiotemporal discretization. The results show that, in forced convection, the effect of the inclination angle is inexistent on the velocity field. However, with the presence of buoyancy effects, which impact flow stability and the transition to turbulence, the inclination influences both velocity and temperature fields. It also shows that selecting the vertical position of the annulus is preferable to obtain hydrodynamic stability in mixed convection. At the same time, from the thermal point of view, it is preferable to select the horizontal position to get dynamic and thermal stability.