Double-diffusive Natural Convective Flow Research Articles

Enhanced Efficiency of MHD-Driven Double-Diffusive Natural Convection in Ternary Hybrid Nanofluid-Filled Quadrantal Enclosure: A Numerical Study

The study investigates the performance of fluid flow, thermal, and mass transport within a cavity, highlighting its application in various engineering sectors like nuclear reactors and solar collectors. Currently, the focus is on enhancing heat and mass transfer through the use of ternary hybrid nanofluid. Motivated by this, our research delves into the efficiency of double-diffusive natural convective (DDNC) flow, heat, and mass transfer of a ternary hybrid nanosuspension (a mixture of Cu-CuO-Al2O3 in water) in a quadrantal enclosure. The enclosure’s lower wall is set to high temperatures and concentrations (Th and Ch), while the vertical wall is kept at lower levels (Tc and Cc). The curved wall is thermally insulated, with no temperature or concentration gradients. We utilize the finite element method, a distinguished numerical approach, to solve the dimensionless partial differential equations governing the system. Our analysis examines the effects of nanoparticle volume fraction, Rayleigh number, Hartmann number, and Lewis number on flow and thermal patterns, assessed through Nusselt and Sherwood numbers using streamlines, isotherms, isoconcentration, and other appropriate representations. The results show that ternary hybrid nanofluid outperforms both nanofluid and hybrid nanofluid, exhibiting a more substantial enhancement in heat transfer efficiency with increasing volume concentration of nanoparticles.

Numerical analysis of double-diffusive natural convective flow of Ostwald-de Waele fluid in an irregular enclosure with a circular obstacle

PurposeThe current study aims to enhance the double diffusive natural convection in an Ostwald-de Waele fluid filled in a hexagonal enclosures using non-uniform magnetic field embedded with circular obstacle. The upper wall has maximum temperature Th∗ and concentration (Ch∗) whereas the lower wall is kept at minimum temperature Tc∗ and concentration Cc∗. The parameters that play a significant role in the heat and mass transfer are evaluated, including Hartmann number, power law index, Rayleigh number and buoyancy ratio. Design/Methodology/approachIn two-dimensions, the governing formulation is written as a set of balancing equations for velocities, pressures, energies and concentrations. The nonlinear governing PDEs are solved using numerical approach based on Finite Element Method (FEM). The discretization is performed using the stable finite element pair ℘2/℘1. Code validation and results are ensured by conducting a grid convergence and comparison test respectively. FindingsThe influence of flow on velocity, isotherms and iso-concentration field is examined by analyzing a broad variety of variables such as power-law index 0.7≤n≤1.2, Hartmann number 0≤Ha≤50, Rayleigh number 104≤Ra≤106, inclination angle 0°≤γ≤90° and buoyancy ratio -2≤N≤2. The findings are displayed graphically, including the flow, temperature and concentration fields. Heat and mass transfer rates are maximum for shear thinning fluids while for shear thickening fluids it reduces, whereas it is maximum for concentration dominated assistant flow and minimum for concentration dominant counter flow. ApplicationThe novel aspects of the research include its thorough examination of solar thermal power conversion and its inventive energy deficiency devices and a wide range of electrical design applications.

Bifurcation analysis of combined double-diffusive natural convection and thermal radiation under a non-uniform magnetic field in a wavy enclosure

In the current work, the bifurcation phenomenon of a double-diffusive natural convection flow is analyzed for a non-uniform magnetic field applied to a wavy enclosure in the presence of radiation, for the first time. The finite volume method has been utilized to simulate volumetric radiation. To solve the continuity, momentum, energy, and species equations, the multiple-time relaxation lattice Boltzmann technique is adopted. In addition, the immersed boundary approach has been applied to identify the complex boundaries inside the Cartesian coordinates system. The effects of specific pertinent parameters, including the optical thickness (0.1≤τ≤100), Buoyancy ratio (-5≤N≤5), Rayleigh number (104≤Ra≤105), wave amplitude (0≤λ≤0.2), and Hartmann number (0≤Ha≤50) on thermohydrodynamic characteristics of the system have been investigated. The results indicated that an increase in Hartmann number disappears the bifurcation phenomenon. In addition, it was observed that the initial condition of hot temperature and high concentration leads to instability in the flow. In the radiation case for λ>0.1, 5<τ<30, and 15≤Ha≤30, the flow appears unsteady. Bifurcation occurs in all values of wavy amplitude, and optical thickness studied. Heat and mass transfers decrease when the initial condition is cold temperature and low concentration. Also, Radiation does not affect the critical Rayleigh number.

Entropy optimization of MHD non-Newtonian fluid in a wavy enclosure with double diffusive natural convection

This study investigates the impact of an inclined magnetic field (MHD) on entropy generation in double diffusive natural convective flow in a wavy enclosure filled with a non-Newtonian Casson fluid. The Galerkin Finite Element Method (GFEM) is employed to numerically solve the standard formulation, utilizing quadratic polynomials for momentum interpolation and a linear interpolating function for model approximation. The discretized system is resolved using Newton’s approach and PARDISO's matrix factorization. Through simulations of varying ranges of Rayleigh numbers Casson parameter Hartmann numbers Lewis numbers and inclined angle gamma the study provides valuable insights into the behavior of double diffusive natural convection in the wavy enclosure. Isotherms, iso-concentration contours, and streamlines are analyzed to assess different input distributions, and the study presents graphical representations and tabular data on heat transfer, mass transfer rate, and entropy production.

Non-Newtonian MHD double diffusive natural convection flow and heat transfer in a crown enclosure

Double diffusion natural convection phenomenon has gained significant attention in different fields of life for example geology, oceanography, metallurgy and astrophysics. The present disquisition is to investigate the mathematical analysis of fluid flow in a waver cavity in the presence of heated circular center of the cavity. The mass and heat transfer on MHD Casson fluid flow are the main focus of current study. The circular center of cavity is kept fixed and heated while the right and left walls of the wavy cavity are cold. The Lorentz force is also taken into consideration. The mathematical problem is governed in form of coupled partial differential equations and is solved by using well know finite element method. Flow distribution analysis is discussed in form of streamlines, isotherms and isoconcentration contour patterns. The obtained results are also represented in the form of kinetic energy, local heat, and mass fluxes. It is noted that under the increasing effect of the Casson parameter rate of heat transfer increase while the rate of mass transfer decrease.

On the performance of curvature stabilization time stepping methods for double-diffusive natural convection flows in the presence of magnetic field

This paper considers analytically and numerically the curvature-based stabilization method for double-diffusive natural convection flows in the presence of magnetic field. Unconditionally stable and optimally accurate second-order approximations are obtained. The impact of curvature stabilization on different flow fields are presented for several numerical test problems.

CFD-based analysis of entropy generation in turbulent double diffusive natural convection flow in square cavity

The present study concerns the problem of natural and double diffusive natural convection inside differentially heated cavity filled with a binary mixture composed of air and carbon dioxide (CO2). Temperature and CO2 concentration gradients are imposed on both perpendicular left and right walls. Simulations have been performed using the CFD commercial code ANSYS Fluent by solving continuity, momentum, energy and species diffusion equations. Numerical results obtained have been compared to data from the literature for both natural convection thermosolutal cases under laminar and turbulent regimes. For turbulent runs the RNG k-ε model has been selected. A good agreement has been noted between the different types of data for both cases for Rayleigh number ranging between 103 and 1010 and buoyancy ratio between -5 and +5. Entropy generation rates due to thermal, viscous and diffusive effects have been calculated in post processing for all cases.

Double-Diffusive Natural Convective Flow of a Nanofluid past an Inclined Wavy Plate in a Non-Darcy Porous Medium

In this paper, the double-diffusive convective flow along an inclined semi-infinite wavy plate in a nanofluid saturated non-Darcy porous medium is investigated numerically. Following Prandtl’s transposition theorem, a coordinate transformation is used to transform the irregular wavy surface into a smooth surface. The convective type thermal boundary condition is taken into account and also the Brownian motion and thermophoresis effects are considered into the present nanofluid model. The governing transport equations are initially reshaped into a system of coupled ordinary differential equations by choosing suitable similarity transformations and then solved numerically by using the Spectral Local Linearization Method (SLLM). The effects of various flow influenced parameters on the fluid flow, heat and mass transfer characteristics are explored and exhibited graphically.

Effects of Microstructure on Three-Dimensional Double-Diffusive Natural Convection Flow of Micropolar Fluid

This work presents a three-dimensional numerical study on double-diffusive natural convection in a cubic cavity filled with a micropolar fluid. The flow is driven by buoyancy forces due to temperature and solutal gradients. Constant temperature and concentration are imposed along the two vertical sidewalls of the cubic enclosure, while the remaining walls are adiabatic and impermeable. The governing equations are expressed in the vorticity-stream function formulation and then solved numerically using the control volume finite method. Numerical results are compared with the case of a Newtonian fluid. The influences of the micro-constituents of the micropolar fluid are depicted. The results show different transitions of the structure of the main flow when varying the vortex viscosity parameter. It is also observed that both the heat and mass transfer rates and the three-dimensional character of the flow are reduced by increasing the vortex viscosity parameter.

Peristaltic pumping with double diffusive natural convective nanofluid in a lopsided channel with accounting thermophoresis and Brownian moment

In the current study, double-diffusive natural convective peristaltic flow of a nanofluid with induced magnetic field in an asymmetric porous channel is discussed. The five coupled equations are solved analytically using with new analytical techniques detail of which is given in solution section. The analytical solutions for pressure gradient and pressure rise, velocity profile, temperature, solutal concentration, and nanoparticle fraction are evaluated and presented through graphs.

Magnetohydrodynamic double-diffusive natural convection for nanofluid within a trapezoidal enclosure

Double-diffusive natural convection flow in a trapezoidal cavity with various aspect ratios in the presence of water-based nanofluid and applied magnetic field in the direction perpendicular to the bottom and top parallel walls is investigated. The bottom and top parallel walls are considered to be insulated, whereas left and right walls are assumed to be uniformly heated and cold, respectively. The numerical computation is carried out to find the streamlines, isotherms, isoconcentrations, average Nusselt number, and average Sherwood number. This study is done for various values of Rayleigh number $$(10^{5}\le Ra \le 10^{7})$$ , Hartmann number $$(0\le Ha \le 120)$$ , various aspect ratios $$(0.5\le A \le 2)$$ , the solid volume fraction $$(0\le \varphi \le 0.1)$$ , and the inclination angle of cavity $$(\phi )$$ . It is found that the strength of vortex decreases/increases as the magnetic field parameter/aspect ratio increases. It is also found that increase in the Rayleigh number causes natural convection due to the increase in the buoyancy forces. In nanofluid, mass transfer ratio is more effective than base fluid.

Double Diffusive Natural Convection Flow Over a Wavy Surface Situated in a Non-absorbing Medium

This analysis discuss the influence of heat and mass transfer on natural convection boundary layer flow of thermally radiating wavy surface. To make the surface radiating; Stephan-Boltzmann law is used in the boundary conditions. Therefore, convection and thermal radiation interact simultaneously with the aid of Stephan-Boltzmann law and ultimately producing highly nonlinear boundary conditions. The governing coupled boundary layer equations are switched into suitable form by using primitive variable formulations over which two-point iterative finite difference scheme is applied to obtain the unknown quantities. Physical quantities like wall shear stress, rate of heat transfer and rate of mass transfer are expressed graphically by varying significant emerging parameters: surface radiation (R), radiative length parameter (ξ), buoyancy ratio parameter (N) and amplitude of the wavy surface (α). Comparison of numerical results is also done in tabular form with the earlier study of Siddiqa et al. (2013) in order to validate the results.

Double Diffusive Natural Convective Flow over a Vertical Plate with Chemical Reaction

Chemically reactive fluid flow over a vertical plate placed in a thermally stratified medium is presented here. A parametric study illustrating the influence of Prandtl number, Schmidt number, buoyancy ratio parameter, stratification parameter and chemical reaction parameter on the velocity, temperature, concentration profiles are studied. The chemical reaction parameter increases, the velocity is found to decreases. From the numerical value, we conclude that the variation between the steady state and temporal maximum increases gradually as S increases.

Numerical Study of Double-diffusive Natural Convection in a Window Shaped Cavity Containing Multiple Obstacles Filled with Nanofluid

In the present study, double-diffusive natural convection flow inside a window shaped cavity containing multiple obstacles filled with nanofluid is studied numerically. Water base nanofluid containing various nanoparticles including Ag, Cu and Al2O3 are considered as working fluid. The left and right inclined walls of the cavity are maintained at a relatively low temperature and low concentration while the vertical walls are adiabatic and impermeable. The non-uniform temperature and concentration are imposed along the bottom wall of the cavity. The governing equations are transformed to the dimensionless form and solved numerically using Galerkin weighted residual technique of finite element method. The influence of pertinent parameters such as thermal Rayleigh number and Lewis number and volume fraction of nanoparticles on the heat and mass transfer and fluid flow is studied. The results are obtained in terms of streamlines, isotherms, isoconcentrations, average Nusselt number and average Sherwood number for the considered parameters and it is observed that the flow pattern, temperature and concentration fields are affected by the variation of the parameters.

MHD Double Diffusive Natural Convection Flow Over Exponentially Accelerated Inclined Plate

AbstractAn investigation of unsteady MHD double diffusive natural convection flow of a viscous, incompressible, electrically conducting, heat absorbing, radiating and chemically-reactive fluid past an exponentially accelerated moving inclined plate in a fluid-saturated porous medium, when the temperature of the plate and the concentration at the surface of the plate have ramped profiles, is carried out. Exact solutions for the fluid velocity, fluid temperature and the species concentration, under Boussinesq approximation, are obtained in closed form by the Laplace transform technique. The expressions for the shear stress, rate of heat transfer and the rate of mass transfer at the plate are also derived. Numerical evaluations of the fluid velocity, fluid temperature and the species concentration are performed and displayed graphically whereas those of the shear stress, rate of heat transfer and the rate of mass transfer at the plate are presented in tabular form for various values of the pertinent flow parameters.

MHD Double Diffusive Natural Convection Flow Over Exponentially Accelerated Inclined Plate

AbstractAn investigation of unsteady MHD double diffusive natural convection flow of a viscous, incompressible, electrically conducting, heat absorbing, radiating and chemically-reactive fluid past an exponentially accelerated moving inclined plate in a fluid-saturated porous medium, when the temperature of the plate and the concentration at the surface of the plate have ramped profiles, is carried out. Exact solutions for the fluid velocity, fluid temperature and the species concentration, under Boussinesq approximation, are obtained in closed form by the Laplace transform technique. The expressions for the shear stress, rate of heat transfer and the rate of mass transfer at the plate are also derived. Numerical evaluations of the fluid velocity, fluid temperature and the species concentration are performed and displayed graphically whereas those of the shear stress, rate of heat transfer and the rate of mass transfer at the plate are presented in tabular form for various values of the pertinent flow parameters.

An Unsteady Double-Diffusive Natural Convection in an Inclined Rectangular Enclosure with Different Angles of Magnetic Field

An unsteady double-diffusive natural convection flow in an inclined rectangular enclosure subject to an applied magnetic field and heat generation parameter is studied. The enclosure is heated and concentrated from one side and cooled from the adjacent side. The other two sides are adiabatic. The governing equations are solved numerically using a staggered grid finite-difference method to determine the streamline, isotherm and iso-concentration contours. We have further obtained the average Nusselt numbers and average Sherwood numbers for various values of buoyancy ratio and different angles of the magnetic field by considering three different inclination angles of the enclosure while keeping the aspect ratio fixed. The results indicate that the flow pattern, temperature and concentration fields are significantly dependent on the buoyancy ratio and the magnetic field angles. It is found that different angles of the magnetic field suppress the convection flow and its direction influences the flow patterns. This leads to the appearance of inner loop and multiple eddies.

Double-Diffusive Natural Convective Flow of a Nanofluid Over a Vertical Cylinder

Double-Diffusive Natural Convective Flow of a Nanofluid Over a Vertical Cylinder

A model of coupled thermosolutal convection and thermoelasticity in soft rocks with consideration of water vapor absorption

The unsteady double-diffusive natural convection flow in a rectangular enclosure filled with soft rocks which are subjected to humid air, including water vapor absorption and thermoelasticity, is studied numerically. The high order compact finite difference schemes are adopted for better simulation of this problem, and a Darcy–Brinkman–Forchheimer extended model combined with the absorption and thermoelasticity effects is introduced. The effects of the thermal and solutal Rayleigh numbers, hygroscopicity, Darcy numbers and thermoelasticity on the flow are investigated in detail. Results are presented in the form of streamlines and isolines of temperature and mass fraction as well as the plots of average Nusselt and Sherwood numbers over the walls under different conditions. The flow structure develops from conduction-dominated to steady convection-dominated as increasing Rayleigh number or increasing buoyancy ratio as well as increasing Darcy numbers. The thermoelasticity effects of soft rocks play an important role in the analysis of thermal convection flow by the change of temperature and permeability, while the water vapor absorption effects may have a slight effect on the flow in the beginning and vanish with the absorption effects becoming weak. Nevertheless, the effect may significant reduce the mechanical strength properties of soft rocks.

Double-diffusive natural convective boundary-layer flow of a nanofluid over a stretching sheet with magnetic field

Purpose – The purpose of this paper, is to study the MHD double-diffusive natural convection of a nanofluid over a linearly stretching sheet using the Buongiorno model. Design/methodology/approach – The transport equations are transformed into coupled similarity equations. The numerical self-similar solutions are compared with the literature for the special case of pure fluid flow and found to be in good agreement. Graphical results are presented to illustrate the effects of various fluid flow, heat transfer and nano concentration parameters for both assisting and opposing flows. Findings – It is found that the heat transfer rate increases as nanoparticles and salt are suspended in water. It is also found that dual solutions exist for the stretching parameter. Originality/value – First paper on this model for stretching sheet.