Natural Convection Flow Research Articles

On Arrhenius steady hydromagnetic heat transfer to natural convection flow in a stretching upright sheet: viscous dissipation and Newtonian heating

Purpose The purpose of this study is to investigate the impact of Arrhenius kinetics on hydromagnetic free convection of an electrically conducting fluid flowing past a vertically stretched sheet maintained at a constant temperature, considering viscous dissipation. In this study, the understanding of the Biot number is essential for comprehending and enhancing heat transfer processes in a flow. Mastering this concept is crucial for the efficient design and management of various industrial and natural systems. The effect of Newtonian heating is accurately addressed by adjusting the traditional temperature boundary condition. Design/methodology/approach The presiding inconsistent Partial differential equations are contrasted to ordinary differential equations by similitude changes and the solutions are completed numerically by fourth-order Runge-Kutta (RK-4) and shooting procedures. Tables and graphs feature vividly in annotating the outcomes of changing parameters on the flow. Findings Notably, the Biot number significantly impacts temperature gradients and distribution, which subsequently affect the flow’s velocity and thermal characteristics; that is, velocity and temperature contours increase directly to an upsurge in the Biot number. Contrasting with existing work, a perfect harmony is experienced. Arrhenius kinetics are essential for predicting and managing fluid flow behaviour in systems where reactions are sensitive to temperature. Grasping this relationship helps engineers and scientists enhance process efficiency, ensure safety and optimize fluid-based systems. Similarly, Newtonian heating significantly impacts fluid flow by affecting temperature distribution, viscosity, buoyancy-driven flows and flow stability. Mastering the control of this heating process is vital in both natural and engineered fluid systems. Technical applications of this research include variation cooling and atomic power generation refrigeration. Originality/value The distinguishing quality of this research lies in the scrutiny of Arrhenius steady hydromagnetic heat transfer to natural convection flow in a stretching upright sheet: viscous dissipation and Newtonian heating. To best of the authors’ understanding, a problem like this has not been considered. The findings in this work will give useful information to scientists and engineers.

Thermo-Magnetic Bioconvection Flow in A Semi-Trapezoidal Enclosure Filled With A Porous Medium Containing Oxytactic Micro-Organisms: Modelling Hybrid Magnetic Bio-Fuel Cells

Abstract Hybrid fuel cells are becoming increasingly popular in 21st century energy systems engineering. These systems combine multiple features including various geometries, electromagnetic fluids, bacteria (micro-organisms), thermo-solutal convection and porous media. Motivated by these developments in the present work we simulate the two-dimensional magnetohydrodynamic (MHD) natural triple convection flow in a semi-trapezoidal enclosure saturated with electrically conducting water containing oxytactic microorganisms and oxygen species. Darcy?s model is deployed for porous media drag effects. The primitive governing partial differential conservation equations for mass, momentum, energy, oxygen species and motile micro-organism species density are transformed using a vorticity-stream function formulation and non-dimensional variables into a nonlinear boundary value problem. A numerical solution is obtained using a finite difference method with incremental time steps. The mathematical model features a number of controlling parameters i.e. Prandtl number, Rayleigh number, Bioconvective Rayleigh number, Darcy parameter, Hartmann (magnetic body force) number, Lewis number, Péclet number, Oxygen diffusion ratio, fraction of consumption oxygen to diffusion of oxygen parameter. Transport characteristics (streamlines, isotherms, oxygen iso-concentration and motile micro-organism concentration) are computed for several of these parameters. Microorganisms? impact on the rate of heat transfer at the boundaries is found to be beneficial or destructive, depending on combination of other parameters in the simulations. Additionally, Nusselt number and oxygen species Sherwood number are computed at the hot vertical wall. The simulations are relevant to hybrid electromagnetic microbial fuel cells.

Three-dimensional stability of natural convection flows in inclined square enclosures

The three-dimensional stability of two-dimensional natural convection flows in a heated, square enclosure inclined to the horizontal is investigated numerically. First, the computational procedure is validated by comparison of base flow solutions to results reported in literature across a range of inclinations. A bi-global linear stability analysis is then conducted to investigate the stability of these two-dimensional base flows to infinitesimal three-dimensional perturbations, and the effect that buoyancy forces (defined by a buoyancy number $R_N$ ) and enclosure inclination $\theta$ have on these stability characteristics. The flow is first observed to become three-dimensionally unstable at buoyancy number $R_N = 213.8$ when $\theta$ is $180^\circ$ ; this increases to $R_N = 2.54 \times 10^4$ at inclination $\theta =58^\circ$ . It is found that the two-dimensional base flow is more unstable to three-dimensional perturbations with the critical $R_N$ corresponding to three-dimensional instability being significantly lower than its two-dimensional counterpart across all considered inclinations except $83^\circ \leq \theta \leq 88^\circ$ , where the most unstable mode is a two-dimensional oscillatory mode that develops in the boundary layers along the conducting walls. Eight different leading three-dimensional instability modes are identified, with inclinations $58^\circ \leq \theta < 88^\circ$ transitioning through an oscillatory mode, and inclinations $88^\circ \leq \theta \leq 180^\circ$ transitioning through a stationary mode. The characteristics of the primary instability modes corresponding to inclinations $88^\circ \leq \theta \leq 179^\circ$ indicate the presence of a Taylor–Görtler instability.

Numerical Study on the Influence of Solutal Buoyancy on Mixed Convection Heat and Mass Transfer in Skewed Domain

This study examines how variations in solutal buoyancy force affect mixed convection heat and mass transfer in a skewed domain. The thermal buoyancy is fixed at 105 for all the cases and mixed convection is induced due to the rotation of a cylinder in clockwise and counterclockwise directions. The solutal buoyancy is varied by changing the buoyancy ratio (0.5, 1, and 1.5). In the present investigation, OpenFOAM 5.0 has been employed to compile the heat and mass transfer solver by coupling energy and concentration equations with Soret and Dufour parameters. The Navier-Stokes equation along with Boussinesq term is included for mixed convection flow analysis. The cylinder rotation is kept constant to maintain the Reynolds number at 1000 at a fixed Richardson number of 1. It is found that for natural convection flow with a stationary cylinder, the heat and mass transfer are higher and stable at low buoyancy ratios. However, for mixed convection flow cases, the increase in heat and mass transfer is maximum and periodic with higher buoyancy ratios.

Buoyancy-driven flow for surface reaction on vertical walls in multilayered open cavities.

This study analyzes the influences of surface reactions on the natural convective flow, temperature, and oxygen concentration distributions in vertically placed multilayered cavities. A mathematical model for this problem is formulated with proper boundary conditions. At first, the governing equations are made dimensionless using the variable transformations. Then, those are solved utilizing the finite element method (FEM), and the stream function is calculated from the Poisson equation. Numerical results show that the maximum stream function is significantly increased while maximum temperature and remaining oxygen concentration are considerably decreased with higher Rayleigh number. On the contrary, the buoyancy force parameter and the Lewis number cause an increase in maximum values of stream function and temperature but a decrease in remaining concentration. For increasing Lewis number and reactant consumption parameter, the flow structure in cavities significantly changes. In addition, maximum values of stream function and temperature are significantly increased with the increase of the heat release parameter. When the opening heights are wider, maximum stream function and remaining concentration are higher, however maximum temperature first becomes lower and then becomes higher. For any value of the parameters, the maximum flow intensity occurs adjacent to the bottom opening of the top cavity of the multilayered open cavities. However, maximum temperature is seen at the top left corner of the top cavity of the system.

Thermal enhancement using variable characteristics and tripartite diffusion features of solar aircraft wings in context of Reiner-Philippoff hybrid nanofluid passing through a parabolic trough solar collector

The application of solar energy to manufacturing processes and thermal power has changed dramatically. This time, the analysis of solar radiation and the possible combination of solar radiation and nanotechnology to increase the efficiency of solar-powered aircraft becomes a significant area of research. Solar-thermal applications often use parabolic trough solar collectors (PTSCs) to achieve high temperatures. This is a theoretical study that discuss the effects of hybrid nano-solid particles on the parabolic trough’s surface collector which is located inside the solar aircraft wings. For this investigation, the non-Newtonian Reiner-Philippoff model; a renowned and cutting-edge type of thermally efficient fluid as well as the stability triple diffusive boundary layer natural convective flow contained in a Darcy-Forchheimer porous medium have been taken into consideration. To verify the thermophysical behavior of the suggested model, unique hybrid nanoparticles copper along with zirconium dioxide with engine oil as base fluid (Cu+ZrO2/EO) has been added to the solar aircraft wings to improve the heat transfer performance. Scientists are currently investigating how to use solar radiation and nanotechnology to increase aircraft manufacturing. To investigate the phenomenon of heat transfer rate, a hybrid nanofluid stream is traveling in the direction of a parabolic-shaped trough found inside solar airplane wings. Solar thermal radiation was the term used to describe the heat transfer process. Heat source/sink phenomena, various slip boundary conditions, thermal radiative, chemical reaction, variable thermal conductivity, and variable molecular diffusivity are some of the special characteristics that are taken into account while assessing the heat transfer efficiency of airplane wings. With the utilization of the appropriate similarity transformations, partial diferential equations that represent the mathematical model can be decreased to ordinary diferential equations. To address the obtained dimensionless ordinary diferential equations, MATLAB’s Lobatto IIIA numerical technique was employed. By comparing the obtained results with the current literature, the credibility of the numerical results is ascertained. It’s vital to remember that velocity reduces as the Bingham number parameter increases. Elevation of thermal radiation enhances the functionality of aircraft wings that are exposed to heat transfer. Moreover, the rate of heat transfer is enhanced by positive variations in heat source and thermal conductivity effects.

Boundary control of unsteady natural convective slip flow in reactive viscous fluids

We consider the optimal control of unsteady natural convective flow of reactive viscous fluid with heat transfer. It is assumed that Newton's law governs the heat transfer within an exothermic reaction under Arrhenius kinetics and Navier slip condition on the lower surface of the channel. The flow is examined in a vertical channel formed by two infinite vertical parallel plates, with a distance (H) between them. Time-dependent natural convective slip flow of reactive viscous fluid and heat transfer equations are solved in a unit interval using the Galerkin-Finite Element Method (FEM) with quadratic finite elements in space and the implicit Euler method in time. The direct solutions are obtained for testing various values of the problem parameters: the Biot number, the Frank Kamenetskii parameter, the Navier slip parameter, and the computation of the skin friction and the Nusselt number $(Nu)$. The optimal control problem is designed for the momentum and energy equations to derive the fluid-prescribed velocity and temperature profiles by defining controls on the boundary of the domain in two ways: (a) controls are formulated as parameters in the boundary conditions, such as slip length and Biot number; (b) controls are assigned as time-dependent functions in the boundary conditions, representing the slip velocity and the heat transfer rate. Following a discretize-then-optimize approach to the control problem, optimization is performed by the SLSQP (Sequential Least Squares Programming) algorithm, a subroutine of SciPy. Numerically simulated results show that the proposed approach successfully drives the flow to prescribed velocity and temperature profiles.

THE EFFECT OF MAGNETIC PARAMETER OVER A VERTICAL WAVY SURFACED RIGHT CIRCULAR CONE IN PRESENCE OF NATURAL CONVECTION

The novelty of this study lies in the combination of wavy cone and magnetic field. The interaction between the velocity decrease and the temperature increase has a various applications. This phenomenon has potential applications in fields such as heat transfer, where there is ability to control temperature profiles. Employing magnetic field can be useful in heat exchangers, cooling systems and other thermal processes. The effects of magnetic fields on fluid flow and heat transfer can be relevant in material processing and manufacturing. This work presents the influence of magnetic field on a vertical wavy cone immersed in viscous fluid, in the presence of natural convection flow with viscosity inversely proportional to linear temperature function. The dominating problem is nonlinear partial differential equations, which is transformed into non-dimensional partial differential equations by using the dimensionless variables, and the wavy surface effect is eliminated from the boundary conditions applying these dimensionless variables. The transformed equations are solved numerically by finite difference (fully implicit method). The numerical results are obtained for magnetic parameter, Prandtl number, surface amplitude, cone half-angle and viscosity variation parameter and their effect on velocity, temperature and Nusselt number. The effect of increasing the magnetic parameter reduces the velocity and increases the temperature. Redundancy of Prandtl number increases the temperature, while the increase of Cone half-angle (CHA) increases the velocity profile. The influence of increasing the viscosity parameter tends to increase the Nusselt number.

Numerical Study on the Effect of Trapezoidal‐Wave Shaped Partition on Natural Convection Flow Within a Porous Enclosure

ABSTRACTThe use of a trapezoidal‐wave shaped diathermal partition to reduce natural convection flow and heat transfer within a fluid‐saturated, differentially heated porous enclosure is investigated in this study. This work is motivated by the need to control and reduce convective heat transfer in differentially heated porous enclosures, impacting applications like energy‐efficient building materials, thermal insulation, and improved heat exchangers. The study aims to disrupt convection currents and minimize thermal transfer. The Darcy flow model, representing fluid flow in porous media, is applied here and solved using the successive accelerated replacement (SAR) scheme with a finite difference method. Key parameters are varied to explore their effects on thermal and flow patterns. These parameters include the partition's length (with values between ), height (spanning from ), and distance from the left wall of the enclosure (), along with the modified Rayleigh number, which ranges from . Through computational visualization of streamlines and isotherms, this study examines how changes in partition geometry influence flow deviations. Results indicate that the trapezoidal partition allows flexibility in adjusting its geometrical parameters, effectively reducing convection flow strength without significant compromise. A drop of 41.13% in flow strength and about 56% reducted in heat transfer is achieved for trapezoidal partition with smaller edge length These findings suggest that such a partition setup can significantly improve thermal management in systems where fluid‐saturated porous enclosures are subject to differential heating.

Unsteady MHD Casson fluid flow past a vertical plate in the presence of viscid dissipation and Dufour effects

PurposeThis research investigates the impact of Dufour effects and viscous dissipation on unsteady magnetohydrodynamic (MHD) natural convection in an incompressible, viscous, and electrically conductive fluid over a vertically oscillating flat plate. The study highlights the significance of magnetic fields in influencing thermal and mass transfer, particularly in the context of thermal radiation. Computational fluid dynamics method including finite difference or finite element techniques can be used to crack the governing equations of the fluid flow. In this work, we used the finite element method (FEM) numerical technique to analyze the numerical behavior of unsteady boundary layer flow of Casson fluid with natural convection past an oscillating vertical plate. Key parameters such as skin friction, temperature, concentration, velocity and Sherwood numbers are derived and analyzed. The results demonstrate that viscous dissipation significantly elevates the fluid temperature, while an increase in the radiation parameter is associated with a decrease in internal friction at the plate. These findings provide critical insights into the interplay between thermal radiation and magnetic fields in MHD flows, with potential applications in engineering systems involving heat and mass transfer, such as cooling systems and material processing. This study underscores the importance of understanding these dynamics for optimizing the performance of MHD applications in various industrial settings.Design/methodology/approachThe mainly authorized and energetic FEM to explain the non-linear, dimensionless partial differential equations (11–13) via equation with boundary conditions (14) makes use of Bathe (36), Reddy (37), Connor (38) and Chung (39). Following are the key steps that make up the method: discretize the domain, derivation of element equation, assembly of element equation, imposition of boundary condition and solution of assembly equation.FindingsThis study examined the impact of viscid dissipative radiation and the Dufour effect on unsteady one-dimensional MHD natural convective flow of a viscous, incompressible, electrically conducting fluid past an infinite moving vertical flat plate with a chemical reaction. Numerically solving the governing equations using the FEM approach is efficient and precise, aiming to be applied to fluid mechanics and related problems. Along with their effects on temperature, concentration and velocity, the following parameters are included: the mass Grashof number, the Soret number, the Grashof number, the Prandtl number, chemical reaction, the Schmidt number, radiation and the Casson parameter. Both the Grashof numbers of thermal and mass rates (Gr, Gm) make an increment in the velocity region. The velocity decreases with an increase in the magnetic parameter. The velocity increases with an increase in the permeability of the porous medium parameter. The temperature flow rate is higher for both Dufour and Viscid dissipation, while a decrement is noted of both Prandtl number and radiation effects. The decrementing behavior of the concentration region is observed at supreme inputs of chemical reaction coefficient and Schmidt number.Originality/valueThis is an original paper and not submitted anywhere.

Impact of Dual Phase Lag on Natural Convection Flow in a Porous Vertical Channel in the Presence of Periodic Boundary

ABSTRACTThe dual‐phase‐lag (DPL) heat conduction model is utilized in this research to analyze the fluid flow of viscous fluid passing through a porous vertical channel with periodic boundary conditions. Periodic heating is subjected to the channel boundary. Equations regarding the model, including the momentum and energy equations, in which the DPL term is incorporated, all in dimensional form, are stated and are being transformed to their dimensionless form, then solved analytically by undetermined coefficients and variation of parameters. The actual expressions of temperature and velocity, as well as the heat transfer rate and skin friction, are determined. The effects of the DPL parameters, suction/injection, Prandtl number, heat source/sink, and Strouhal number on the dimensionless temperature and velocity profiles are demonstrated using graphs that are constructed with the aid of MATLAB. It was found during the investigation that the introduction of the DPL model, together with suction/injection in the channel, enhances the velocity and fluid temperature within the channel. Also, the decreasing effect of temperature gradient phase lag on fluid temperature and velocity conversed with that of heat flux phase lag. As an important contribution, the discovery of the effects of the phase‐lag parameters of the DPL model and suction/injection on fluid temperature and velocity would significantly help researchers advance the design of electrical and electronic systems.

Magnetohydrodynamic natural convective flow of copper water nanoliquid inside a square cavity with heat absorption/generation

Magnetohydrodynamic natural convective flow of copper water nanoliquid inside a square cavity with heat absorption/generation

Thermal analysis for convective transport of nanoparticles with effective phenomenon of damped shear-thermal flux: A fractional model

The researchers are interested to enhance the temperature characteristics of convection heat transportation investigation. The studies based on nanofluids are accomplished because these phenomena exhibit an abnormal elevation in thermal transportation. This analysis captures historical impacts on heat and momentum transfer that traditional models ignore by using the Caputo fractional derivative in to model damped shear-thermal flux in nanofluid convection. In this manuscript, the natural convection flow, as well as heat transference of nanofluids, is studied. The classical expressions are fractionalized with the help of constitutive shearing stress expression along with Fourier relation. The Caputo kernel (power-law and non-local) engenders the damping on gradients of momentum and temperature; consequently, transportation approaches are affected by the histories entirely of the previous and current time. The fractional differential equations of velocity as well as temperature are solved analytically by invoking Laplace and the finite Sine-Fourier transform method. In a particular case, the solution to the classical model is also found. Moreover, these solutions are described in respect of the Lorenzo-Hartley G-function together with the Mittag-Leffler function. This investigation exposes that rising nanoparticle volume fraction improves the heat transfer rate, however the skin friction coefficient is affected by time and fractional parameters. The influences of diverse parameters are debated graphically. This study has numerous operations in thermal engineering.

Energy-consistent discretization of viscous dissipation with application to natural convection flow

A new energy-consistent discretization of the viscous dissipation function in incompressible flows is proposed. It is implied by choosing a discretization of the diffusive terms and a discretization of the local kinetic energy equation and by requiring that continuous identities like the product rule are mimicked discretely. The proposed viscous dissipation function has a quadratic, strictly dissipative form, for both simplified (constant viscosity) stress tensors and general stress tensors. The proposed expression is not only useful in evaluating energy budgets in turbulent flows, but also in natural convection flows, where it appears in the internal energy equation and is responsible for viscous heating. The viscous dissipation function is such that a consistent total energy balance is obtained: the ‘implied’ presence as sink in the kinetic energy equation is exactly balanced by explicitly adding it as source term in the internal energy equation.Numerical experiments of Rayleigh–Bénard convection (RBC) and Rayleigh–Taylor instabilities confirm that with the proposed dissipation function, the energy exchange between kinetic and internal energy is exactly preserved. The experiments show furthermore that viscous dissipation does not affect the critical Rayleigh number at which instabilities form, but it does significantly impact the development of instabilities once they occur. Consequently, the value of the Nusselt number on the cold plate becomes larger than on the hot plate, with the difference increasing with increasing Gebhart number. Finally, 3D simulations of turbulent RBC show that energy balances are exactly satisfied even for very coarse grids. Therefore, the proposed discretization also forms an excellent starting point for testing sub-grid scale models and is a useful tool to assess energy budgets in any turbulence simulation, with or without the presence of natural convection.

Deep learning based hybrid POD-LSTM framework for laminar natural convection flow in a rectangular enclosure

Abstract Laminar natural convection in side-heated enclosures is characterized by transient phenomena of the working fluid till it reaches steady state. The side heating can done in several ways the most common way being heating one end at constant temperature and cooling the other end. One of the other ways is heating both sides of the enclosure at a constant heat flux. Mathematical modeling of such problems using Computational Fluid Dynamics (CFD) essentially involves considerable amount of computational time and power to predict the flow phenomena observed in actual experimentation. In the last few years, data driven model frameworks have proven to be anefficient way in saving both time and computational cost in several applications. In the present study, a data driven model framework using a combination of unsupervised machine learning (using Proper Orthogonal Decomposition [POD]) and supervised deep learning models (using Long Short Term Memory [LSTM]) has been developed and referred to as POD-LSTM framework. The selection of a few dominant spatial bases and accompanying temporal modes provides us with a reduced order model of the system. The flow is then reconstructed and compared with results of CFD simulations. The Rayleigh number (Ra) chosen for the study is 3.27 × 1010. The estimated time to reach stedy state for this Ra number is 15,000 s. The POD-LSTM framework is trained using data obtained from a validated CFD model for the first 1,000 s. The trained model was then tested to predict temporal dynamics for the entire 15,000 s. The predictions provided by POD-LSTM framework were found upto 98 % accurate compared to the ones predicted by CFD. The computational time and power was however an order of magnitude lower for the POD-LSTM framework than that required for the CFD model.

MHD Natural Convection Flow of Casson Ferrofluid at Lower Stagnation point on a Horizontal Circular Cylinder

MHD Natural Convection Flow of Casson Ferrofluid at Lower Stagnation point on a Horizontal Circular Cylinder

Numerical Investigation of Turbulent Convection Flow in a Rectangular Closed Cavity

Natural turbulent convection in closed cavities has many practical applications in the field of engineeringsuch as the design of electronic computer chips, atomic installation and industrial cooling among others. Inparticular, it enables in achieving a desired micro-climate and efficient ventilation in a building. Recent studiesshow that turbulent flow is affected by variations in Rayleigh numbers, aspect ratio, and heater positionamong others. Temperature is kept constant in all these studies hence inadequate literature on the effectsof temperature on a turbulent flow. In this study, aspect ratio and Rayleigh numbers are kept constant at2 and 1012 respectively and natural turbulent convection flow in a closed rectangular cavity is investigatednumerically as the operating temperature is varied from 285.5K to 293K. The rectangular cavity’s lower wallwas heated and cooling done at the top face wall while the rest of the vertical walls were kept in adiabaticcondition. Material properties such as density of the fluid kept on changing at any given temperature. Thethermal profile data generated influenced the nature of the turbulent flow. The non-linear averaged continuity,momentum, and energy equation terms were modeled by the SST k − ω model to generate streamlines,isotherms, and velocity magnitude for a different operating temperature and presented graphically. The finitedifference method and FLUENT were used to solve two SST k − ω model equations, vortices, and energy withboundary conditions. It was discovered that, as the operating temperature increased turbulence decreaseddue to a decrease in the velocity of the elements and vortices became more parallel and smaller.

Effect of Suction/Injection on Unsteady MHD Natural Convection Flow of Heat Mass Transfer in Porous Channel in the Presence of Soret Term

This research paper explores the effect of suction/injection on unsteady MHD natural convection flow of heat mass transfer in porous channel in the presence of Soret term. The governing partial differential equations are converted to non- dimensional forms and solved numerically by using unconditionally stable and convergent implicit finite difference method. A parametric study illustrating the influence of various physical parameters is performed. It is reported that the velocity profile increases as Soret term, Grashof number, Solutal Grashof number and Porous parameters values increase, while Magnetic field parameter decreases the velocity profile. The temperature profile rises by the influence in increasing values of Variable Thermal Conductivity and decreases by increasing values of Prandtl number and Radiation parameters. While concentration profile increase by the increasing values of Soret term and Chemical reaction. The dependence of the skin friction coefficient, rate of heat transfer and mass transfer on these parameter has been discussed.

Heat Transfer and Entropy Generation on Free Convection Airflow inside a T-shaped Cavity Considering Inner Obstacles

In this study, a numerical analysis of heat and entropy generation on free convection of airflow is performed inside a T-shaped cavity with and without circular obstacles. The T-shaped cavity is formed with two symmetrically isothermal rectangular blocks. A cold temperature is maintained on the cavity's upper wall. The adiabatic walls are connected to heated wall at constant temperature. It is assumed that the flow is laminar, 2-D, and steadily incompressible. The finite element analysis is employed for solving the governing equations. The calculated results are compared and validated with the other published works. The dimensionless velocity (streamlines) and temperature (isotherms) are calculated and illustrated for varying Rayleigh numbers. It is found that the average Nusselt number at the heated walls and entropy generation inside the cavity increase with the increment of Rayleigh numbers. Moreover, the thermal performance effects on natural convection flow are investigated with circular obstacles inside the enclosure. Five cases without and with circular obstacles regarding the boundary conditions are investigated. It is found that the thermal performance of the cavity can be improved by adding two circular obstacles with cool boundary conditions. It is evident that the innovative structure by adding two circular obstacles with cool boundary conditions gives higher average Nusselt number and entropy generation whereas lower Bejan numbers for varying Rayleigh numbers. The study is performed for and . Jagannath University Journal of Science, Volume 11, Number 1, June 2024, pp. 186−202

Laminar boundary layers in three‐dimensional MHD natural convective flow past a semi‐infinite vertical plate with variable sinusoidal suction

AbstractThe primary goal of this study is to investigate how the diffusion‐thermo and thermo‐diffusion affect a three‐dimensional hydromagnetic natural convective flow of a radiating fluid past a uniformly moving isothermal and isosolutal semi‐infinite vertical plate subjected to a sinusoidal suction velocity. The asymptotic series expansion method is adopted to solve the equations governing the flow model and to find the analytical solutions. The effect of variable suction on the flow and transport characteristics is mainly highlighted in the study. Both the diffusion‐thermo and thermo‐diffusion effects improve the fluid velocity.