Mixed Convection Flow Research Articles

Magnetic field effect on mixed convection flow inside an oval-shaped annulus enclosure filled by a non-Newtonian nanofluid

The phenomenon of flow around a static or rotating circular cylinder has significant applications in various engineering fields, such as building, bridge, and structure engineering. It can be used to control flow-induced vibration, blowing or suction, moving surfaces, acoustic thriller, and synthetic jet. Additionally, there is a need to enhance heat transfer rates in many life and industrial applications, including cavity shape enhancement, heating or cooling spread inside a cavity, heat dissipation in electronic devices, thermal mixing in storage units, solar collectors, desalination, and journal bearing lubrication. This study explores the effect of a horizontal magnetic field and a rotating inner circular cylinder on mixed convection within a two-dimensional oval-shaped enclosure filled with a non-Newtonian nanofluid. The Galerkin Finite Element Method (GFEM) is utilized for analysis, with the enclosure undergoing differential heating and cooling on the inner cylinder wall and the enclosure wall, respectively. The nanofluid consists of water infused with copper nanoparticles. The study explores various simulation parameters, including the Richardson number (Ri), Hartmann number (Ha), the inclination angle of the enclosure (β), power-law index (n), circle center eccentricity (e), and nanoparticles volume fraction (φ). It has been observed that as the Ha and n index increase for different Ri values, a wavy trend in local Nusselt number (Nu) profiles along the heat source surface is observed. Additionally, the heat transfer rate decreases with increasing Ri for various combinations of Ha and n index. Under specific conditions, such as Ri = 0.001, Ha = 60, e = 0, φ = 0.09, and β = 90, the results show that, compared to a Newtonian fluid (n = 1), the heat transfer rate exhibits percentage gains of approximately 6.31% for a pseudo-plastic fluid (n = 0.6) and 8.47% for a Dilatant fluid (n = 1.4). The convective heat transfer was significantly enhanced when the eccentricity of the cylinder was positioned in the lower or upper regions of the oval-shaped enclosure, particularly at e = - 0.3. The highest heat transfer rates were observed at β = 60 and 240.

Evaluation of mixed convection-radiation flow of a viscous fluid restricted to a vertical porous channel: A comparative study

This article examines the steady mixed convection flow in an upstanding porous channel of a hydrodynamic viscous fluid that is electrically conductive due to the thermal radiation effect. The homotopy perturbation method (HPM) is used to generate analytical solutions to the governing differential equations that characterize the velocity and temperature flow properties. For relevant temperature jump and velocity slip situations, the effects of mixed convection parameters, thermal radiation parameters, and magnetic field effects on the velocity field, skin friction coefficient, temperature distribution, and heat transfer rate have been described. This research also analyses and compares the results obtained by Abbas et al. (2020) with this present work when HPM was used for the limiting cases. It is interesting to report that an excellent agreement was established, thereby authenticating and validating the accuracy of HPM as a strong tool for obtaining approximate solutions. According to the results of this study, it is possible to effectively control the velocity and temperature gradients by varying the main relevant parameters such as: the mixed convection parameter for a constant pressure gradient, the thermal radiation parameter, the magnetic field effect, the rarefaction parameter, and the wall ambient temperature difference ratio parameter

HARK formulation for entropy optimized convective flow beyond constant thermophysical properties

Background and objectiveOhmic heating has a pivotal role in food processing industry. For example, Ohmic heating in chocolate industry for cocoa beans shell is significant substrate for bioactive compounds recovery sustainability. In addition, the Soret and Dufour effects have importance in chemical and petroleum processes involving separation treatments, convective movements in lakes and solar ponds, solidification, humidity migration in building, drying processes, crystal growth and many others. In view of such applications here we discuss the hydromagnetic mixed convection flow with variable thermophysical properties. Formulation for Reiner-Rivlin material is made. Entropy generation in presence of dissipation, magnetohydrodynamics and radiation are discussed. Thermal relation consists of heat generation and dissipation. Soret and Dufour outcomes are under consideration. Ohmic heating is attended. Binary chemical reactive flow has been accounted. Convective conditions are implemented. MethodologyBy utilization of appropriate variables, we get the ordinary differential equations. ND-solve method is implemented to provide computations. ResultsEvaluation of different variables for flow, concentration, entropy rate and temperature are studied. Analysis of surface drag force and solutal and thermal transport rates via influential variables are examined. An augmentation in velocity is noted for variable viscosity and material parameters. Reverse effect holds for thermal field and flow with variation in magnetic variable. An intensification in thermal distribution and entropy is found through radiation and thermal Biot number. A reverse impact is observed for concentration through Schmidt and Soret numbers. Higher variable mass diffusivity parameter correspond to improves concentration and entropy rate. Brinkman number has increasing trend for entropy rate.

Impact of wind-driven mixed convection on the performance of passive solar desalination with PCM heat storage in varied Moroccan climates

Mixed convection flows are commonly observed in various technological and industrial applications, including solar stills that are exposed to wind currents and other weather conditions. Combined free and forced convection flows can significantly improve the productivity of solar still devices, making them of practical interest. In fact, a passive solar desalination system with heat storage material is investigated in six climate zones of Morocco and presented by six cities namely: Tangier, Rabat, Ifran, Marrakech, Meknes and Errachidia. This study aims to analyze the effect of mixed convection on the inclined surface of solar desalination systems. Thus, a transient Computational fluid dynamics (CFD) model is developed and investigated under the instantaneous climatic data of the different cities aforementioned. The results indicate that forced convection dominated heat transfer during broad daylight, with the Nusselt number increasing as the Reynolds number increased. Overall, the productivity in Tangier city was found to be significantly higher than that of Rabat, Meknes, Marrakech, Ifran, and Errachidia city, with increases of 45.02%, 50.48%, 23.48%, 83.31%, and 24.89%, respectively.

Mixed Convection Boundary Layer Flow over a Horizontal Circular Cylinder in AL2O3-Ag/Water Hybrid Nanofluid with Viscous Dissipation

This paper investigated the mathematical modelling for mixed convection boundary layer flow over a horizontal circular cylinder in hybrid nanofluid with viscous dissipation. The transformed partial differential equations (PDEs) are numerically solved using an implicit finite-difference approach known as the Keller-box method. The numerical solutions for the reduced Nusselt number, , local skin friction coefficient, , temperature profile, and velocity profiles are found and graphically presented in detail. Effects of the Eckert number, Richardson number and nanoparticle volume fraction are all examined and explained. It is found that the increase of volume fraction of nano material in nanofluid has increased the value of skin friction coefficient. The low density of nano oxides such as alumina in hybrid nanofluids also contribute to reduce friction between fluid and body surface. Based on numerical analysis, the combination of nanoparticles in the form of hybrid nanofluid may reduce skin friction phenomena while sustaining heat transfer characteristics comparable to nanofluid. The results in this paper are original and will assist researchers working in the field of boundary layer flow. It can also be utilised as a reference in experimental studies to reduce operating costs.

Significance of mixed convective double diffusive MHD stagnation point flow of nanofluid over a vertical surface with heat generation

The mixed convection double-diffusive MHD flow of boundary layer nanofluids above vertical region is designed. This flow is explained near stagnation point along with heat generation. Using Buongiorno’s model, the properties of Brownian motion, thermophoresis, and diffusion of regular and cross type are included. Using appropriate similarity transformations of the local similarity technique, non-linear unstable PDEs in governing model converted to non-linear ODEs, which were then evaluated numerically by the Keller-box method (KBM) using the computational software MATLAB 2021a. Graphical analysis of possessions of parameters on the boundary layers in profiles of velocity, solute concentration, temperature and nanoparticle concentration is illustrated. The statistics of the reduced Sherwood number and the reduced Nusselt number for solute and nanoparticles in cases of assisting flow and opposing flow are added as well to the results. The fastest rate of heat transfer is achieved in a scenario with a negligible thermophoresis effect. The thermophoresis parameter and the buoyancy parameter of the regular double diffusive appear to rise rather than decrease in the nanoparticles lowered Sherwood number, while the Brownian motion parameter rises. The temperature and layer thickness for heat generation have a quite opposite effect. When the computed numerical findings are compared to earlier published work, it is discovered to be in good percentage. The need for numerous industrial applications and improvements in the efficiency and energy consumption of systems, such as cooling and heating transportation, in water heaters, nuclear reactors, optical devices, turbines, aerodynamics, and electronics, have led to the establishment of this investigation.

Two-phase simulation of entropy optimized mixed convection flow of two different shear-thinning nanomaterials in thermal and mass diffusion systems with Lorentz forces

This research compares the momentum, thermal energy, mass diffusion and entropy generation of two shear thinning nanofluids in an angled micro-channel with mixed convection, nonlinear thermal radiation, temperature jump boundary condition and variable thermal conductivity effects. The RKF 45 approach was used to solve the Buongiorno nonlinear governing model. The effect of different parameters on the flow, energy, concentration, and entropy generating fields have been graphically illustrated and explained. The hyperbolic tangent nanoliquid has a better velocity than the Williamson nanofluid. The Williamson nanofluid has higher thermal energy and concentration than the hyperbolic tangent nanoliquid in the microchannel. The Grashof number, both thermal and solutal, increases the fluid flow rate throughout the flow system. The energy of the nanoliquid is reduced by the temperature jump condition, while the energy field of the nanoliquid is enhanced by the improving thermal conductivity value. The nanoliquids concentration rises as the Schmitt number rises. The irreversibility rate of the channel system is maximized by the variable thermal conductivity parameter.

Heat and mass transfer under MHD mixed convection in a four‐sided lid‐driven square cavity

AbstractThis paper investigates the heat and mass transfer under magnetohydrodynamic mixed convection flow of a binary gas mixture in a four‐sided lid‐driven square cavity. The enclosure's left wall is sinusoidally heated and acts as a source term, while the right wall functions as a sink. The cavity's horizontal walls are adiabatic and impermeable to mass transfer. The governing equations under Boussinesq approximation and stream function‐vorticity formulation are solved using the alternating‐direction‐implicit scheme, a finite‐difference method. The numerical scheme's consistency and stability are demonstrated using the matrix method. The MATLAB code is written, validated against some existing studies, and used to perform numerical simulations. The numerical solutions are graphically examined by visualizing the streamline, isotherm, and concentration contours for nondimensional parameters, such as Hartmann number , heat absorption or generation coefficient , Richardson number , and buoyancy ratio . The magnetic field modifies the temperature and concentration distribution in the cavity, depending on the convection mode. The magnetic field forces the fluid to stagnate in different regions of the cavity, depending on the mode of convection. It was found that the difference between the maximum and minimum temperature and concentration at the cavity's midpoint increases up to 13 and 10 times, respectively, in the natural convection compared with the forced convection. The average Nusselt number on the vertical walls of the cavity is maximum in natural convection in the absence of a magnetic field but reaches a minimum value at in forced and mixed convection. The average Sherwood number on the cavity's vertical walls decreases with the magnetic field in mixed and natural convection.

Chemical Reaction Effects on the Flow of Titanium Dioxide–Water in a Mixed Convective Nanofluid along an Inclined Plate in a Porous Medium

An inclined plate is being approached by a mixed convective boundary layer nanofluid flow of titanium dioxide–water through a porous medium. A numerical analysis has been done to investigate the effects of chemical reactions on the considered nanofluid flow. With the aid of a system of governing partial differential equations, a set of nonlinear ordinary differential equations for taking into consideration nanofluid flow have been derived using appropriate matching transformations. The Runge–Kutta method, as well as the Nachtsheim and Swigert Shooting method, is applied to numerically resolve the group of subsequent nondimensionalized equations. The associated numerical result was then successfully compared with the available published literature in a few unique, limited circumstances. Based on the considered nanofluid flow characteristics for heat as well as mass transfer, the effects of the Schmidt number, the permeability, and the chemical reaction parameters of the titanium dioxide–water nanofluid flow have been examined, assessed, and presented for velocity in conjunction with the local skin friction coefficient, temperature in conjunction with the local Nusselt number, as well as concentration in conjunction with the local Sherwood number. Numerical results reveal that the local Sherwood number Sh, as well as the local Nusselt number Nux, increase, whereas the local skin friction coefficient Cf decreases due to the increase in the chemical reaction parameter Krp.

Evolutionary design investigation applied to mixed convection heat transfer flows over semi-elliptical blocks inserted into a rectangular channel

Evolutionary design investigation applied to mixed convection heat transfer flows over semi-elliptical blocks inserted into a rectangular channel

Evolutionary design investigation applied to mixed convection heat transfer flows over semi-elliptical blocks inserted into a rectangular channel

Evolutionary design investigation applied to mixed convection heat transfer flows over semi-elliptical blocks inserted into a rectangular channel

Irreversibility analysis of mixed convection Jeffrey fluid flow between vertical parallel plates with an inclined magnetic field

Irreversibility analysis of mixed convection Jeffrey fluid flow between vertical parallel plates with an inclined magnetic field

Impact of heat source on mixed convection hybrid ferrofluid flow across a shrinking inclined plate subject to convective boundary conditions

Hybrid ferrofluids have exhibited enhanced heat transfer results in numerous applications. Industry demands like inclination sensors and solar water heaters give a new insight into heat transfer problems on the angle of inclination problems. Thus, this paper is motivated to analyse the effect of inclination angle towards mixed convection hybrid ferrofluid flow, including heat sources and convective boundary conditions, on a porous shrink surface. By utilising a similarity transformation, the intricate nature of the partial differential equations (PDEs) is simplified, transforming it into a set of ordinary differential equations (ODEs) and numerically solved in the bvp4c (MATLAB). A positive correlation was obtained between the current model and past researchers. Besides that, the increase in nanoparticle volume fraction improved the skin friction by approximately 14.79% and 15.00% for opposing and assisting flow regions, accordingly. Altering the inclination angle positively impacted growth by approximately 3.28% and 0.0068% on the skin friction and the heat transfer rate, accordingly. The inclusion of a heat source reduced the heat transfer rate by approximately 0.20% and 0.19% for both opposing and assisting flow regions, respectively. Meanwhile, a greater rise in heat transfer rate by approximately 174.48% when the Biot number, Bi rose.

Optimization of system parameters during conjugate mixed convective flow in a square domain with an oscillating spinning cylinder

A computational analysis has been executed to analyze the combined conduction-mixed convection heat transfer of a rotationally oscillating solid cylinder in a differentially heated square box filled with air. The conjugate mixed convective flow initiates the heat transfer process, where the left-side boundary is isothermally kept to a higher temperature, and the right-side boundary is maintained at a lower temperature. Conduction heat transfer takes place inside the solid cylinder. Navier-Stokes and heat energy conservation equations model the system in the dimensionless pressure-velocity formulation. All these equations are solved via the Galerkin finite element approach. Three different combinations of Grashof (103-105), Reynolds (32–316), and Richardson (0.1–10) numbers are examined to systematically investigate the variations of governing parameters on instantaneous Nusselt numbers and the respective time-averaged values along the hot wall. In each combination, the impacts of the oscillating amplitude and frequency and the variation of cylinder diameter are examined to perform the optimization study. Power spectrum analysis is also done using the Fast Fourier Transform in the frequency domain to visualize the principal frequency of the system. The instantaneous values of the Nusselt number exhibit a wavering pattern over time owing to the recurrent waning and waxing of the thermal boundary layer. For all the cases, the maximum diameter and oscillating amplitude of the cylinder are found to maximize the heat transfer. However, the optimized frequency of the oscillation strongly depends on the selection of the governing parameters. In addition, the principal thermal frequency of the system is determined to be independent of the oscillation frequency.

Flow control using hot splitter plates in the wake of a circular cylinder: A hybrid strategy

A novel and effective hybrid technique, which involves active surface heating strategies in conjunction with the use of passive splitter plates in the wake of the cylinder, is proposed. In this report, we present the results of a numerical investigation on the two-dimensional, laminar mixed convection flow over a circular cylinder with a hot rigid splitter plate attached to it on the wake side. A projection algorithm-based finite volume method is employed to obtain the solution of the coupled, nonlinear governing partial differential equations subjected to Courant–Friedrichs–Lewy conditions. The isothermal heating of the splitter plate under the influence of the gravity field generates an upward buoyancy force in the wake of the cylinder. For different length-to-diameter (L/D) ratios, the effect of heating on aerodynamic, wake, and heat transfer characteristics has been studied for a wide range of parameters; 75 ≤Re≤ 150, 0 ≤Ri≤ 1, and 0.5 ≤L/D≤ 1 at Pr = 0.7. It is observed that the hot splitter plate would bring about conspicuous changes such as asymmetry in the vortex shedding behind the cylinder at low Reynolds numbers. The outcomes demonstrate a notable improvement in convective heat transfer and drag, with gains of up to 7% and 15%, respectively. It is found that the rate of heat transfer and vortex shedding frequency decrease with an increase in L/D ratio. Correlations for the estimation of Strouhal number and Nusselt number have also been proposed which helps provide a more thorough understanding of thermal and aerodynamic features of the hybrid approach.

UNSTEADY MIXED CONVECTION HYDRO-MAGNETIC CASSON THERMO-DIFFUSION FLOW OF REACTING AND DISSIPATING FLUID WITH AN INCLINED MAGNETIC FIELD ALONG AN OSCILLATING SLANTED POROUS PLATE

A finite element numerical simulation is undertaken to explore the aspects of angled magnetic field and thermo-diffusion on an unsteady reacting mixed convection flow of hydro-magnetic Casson dissipating fluid with thermal radiation. The fluid streams across an oscillating tilted plate ingrained in a porous medium including time-altering temperature and concentration. The dimensionless flow, guiding partial differential equations along their associated initial and boundary conditions, are handled, enforcing an efficient finite element scheme. The key parameters affecting the velocity, temperature, and concentration profiles are comprehensively interpreted through graphical representations while the skin friction, heat transfer, and mass transfer rates are outlined via tables. The ultimate results of this study posted that the plate inclination angle, Casson parameter, and applied magnetic strengths are compelled to impede the fluid velocity and local skin friction, whereas the porosity parameter displays a reverse effect. The thermo-diffusion effect amplifies the fluid velocity and species concentration. It also supports that the Eckert number and heat source boost up the velocity and temperature profiles. Moreover, increasing radiation parameter and time crusade results in an upsurge in the Nusselt number. The chemical reaction quickens the Sherwood number, but it decays with the thermo-diffusion parameter. A comparative analysis between the current findings and existing research works in the literature demonstrates the results' precision and exactitude.

Dufour and Soret effects on unsteady MHD mixed convective flow across a stretching curved surface with thermal and velocity slip: A numerical study

Dufour and Soret effects on unsteady MHD mixed convective flow across a stretching curved surface with thermal and velocity slip: A numerical study

MHD Mixed Convection Flow and Heat Transfer due to an Inclined Stretching/Shrinking Sheet

MHD Mixed Convection Flow and Heat Transfer due to an Inclined Stretching/Shrinking Sheet

Aspects of Dual Simulation for Modified Thermal Flux Advances in Non‐Newtonian Reiner–Philippoff Fluid Flow past a Shrinking Plate Embedded in a Porous Medium

This study investigates the effects of non‐Newtonian Reiner–Philippoff fluids on porous media, particularly in the context of steady radiative mixed convection flow and heat transfer near a shrinking plate surface in the presence of magnetohydrodynamics (MHD). The mathematical model is constructed using PDEs and transformed into ODEs via similarity transformations, with numerical solutions obtained using MATLAB’s bvp4c function. The results demonstrate that boundary layer separation occurs slowest for dilatant fluids and fastest for pseudoplastic fluids, with Newtonian fluids exhibiting moderate separation rates. Thermal radiation and media porosity parameters are found to reduce heat transfer by approximately 0.95% and 0.02%, respectively, while accelerating boundary layer separation. Conversely, magnetic effects and suction parameters increase heat transfer by about 0.08% and 4.25%, respectively, enhancing both fluid velocity and temperature. The mixed convection parameter indicates the possibility of dual solutions, with the opposing flow favoring this phenomenon more than the assisting flow. The time‐based stability analysis reveals that the first solution is stable, whereas the second solution is unstable. These findings provide significant insights into the behavior and control of Reiner–Philippoff fluids in practical applications involving porous media and magnetic fields.

Impact of Cattaneo-Christov heat flux on mixed convection flow of a ternary hybrid (Cu-Al2O3-TiO2/H2O) nanofluid over an elongated sheet: A comparative analysis

Impact of Cattaneo-Christov heat flux on mixed convection flow of a ternary hybrid (Cu-Al2O3-TiO2/H2O) nanofluid over an elongated sheet: A comparative analysis