Semi-annulus Enclosure Research Articles

Analysis of magneto-natural-convection flow in a semi-annulus enclosure filled with a micropolar-nanofluid; a computational framework using CVFEM and FVM

Micropolar fluids are the media in which their behavior is affected by the microrotation of the substructure particles. In the present work, the natural-convection flow of a micropolar-nanofluid (Al2O3/water) in the presence of an inclined magnetic field in a semi-annulus enclosure is investigated. The influence of active parameters on magneto-natural convection is investigated. The governing equations (mass, momentum, microrotation, and energy) are numerically solved by CVFEM. Moreover, for some conservative comparisons, the equations are solved by Ansys Fluent CFD code which is conjugated by an innovative nondimensionlization scheme. The effects of important parameters are investigated on the streamlines, isotherms, microrotation contours, the maximum absolute value of stream function (Ψmax), the average Nusselt number (Nuave) and the maximum absolute value of microrotation Nmax∗. The results discovered that the values of Nuave descend with ascending the Hartmann number (Ha) and material parameter (K) while it ascends with ascending Rayleigh number (Ra) and particle volume fraction (ϕ). The value of Nuave descends 10.8% while Nmax∗ increases 19.8% when K increases from 1 to 2. The value of Nuave descends 44.83% when Ha increases from 25 to 75 at λ=45°. The minimum value of Nuave occurs at λ=45° for Ha=25 and at λ=30° for Ha=50 and Ha=75.

Two-phase modeling of the free convection of nanofluid inside the inclined porous semi-annulus enclosure

In the present paper, the modeling of the free convection of two-phase nanofluid inside the inclined porous semi-annulus enclosure is considered. The cavity is filled with Fe3O4-water magnetic nanofluid. Buongiorno and Darcy models are used for modeling two-phase and porous media, respectively. The governing equations are discretized by finite volume method and SIMPLE algorithm. The effect of parameters such as inclination angle of cavity (0 ≤ θ ≤ 90), porous Rayleigh number (10 ≤ Rap ≤ 103), porosity number (ε = 0.4 and 0.7), and volume fraction of nanoparticles (0 ≤ φAve ≤ 0.04) on the flow pattern, temperature field, nanoparticle distribution, and Nusselt number are studied. In low porous Rayleigh numbers, Nusselt number is not the function of porosity number and the inclination angle of the enclosure. Also, Nusselt number increases by adding the volume fraction of nanoparticles. However, in high porous Rayleigh numbers, the heat transfer rate is reduced by increasing the inclination angle of the enclosure. Furthermore, with the increase in the porosity number, Nusselt number is increased.

A computational framework for natural convective hydromagnetic flow via inclined cavity: An analysis subjected to entropy generation

One of the most interested and essential subjective in mechanical science is natural convection analysis in a cavity. Thus, natural convective flow and entropy generation are scrutinized numerically subjected to magnetic field effect in a semi-annulus enclosure which known as the effect of magneto-hydrodynamic (MHD). Firstly, the governing expressions are rewritten in non-dimensional form utilizing the definition of dimensionless parameters, stream function, and vorticity. Secondly, the entropy generation equation is expressed in non-dimensional form. Then governing non-dimensional expressions are computed by control finite element method (CVFEM). Furthermore, the governing expressions are computed employing finite volume method (FVM) utilizing ANSYS Fluent CFD code. A novel criterion for determination of thermal characteristics of cavity based on thermodynamics second relation is introduced that is called ecological coefficient of performance (ECOP). Flow and heat transport features in addition to entropy generation number are examined for distinct values of the Rayleigh number (Ra = 103,104,105), the orientation of the magnetic field (β = 0°,15°,30°,45°,60°,75°,90°), and Hartmann number (Ha = 0,5,10,15,20). For validation, the entropy generation number and average Nusselt number are compared with those available in literature and excellent agreement is observed. Isotherms and streamlines are calculated using CVFEM and FVM. Some correlations for entropy generation number are proposed. The results show that for constant Rayleigh number, the entropy generation number decays with increasing Hartmann number. Also, for each Hartmann number, there is an optimum inclination angle of magnetic field that gives a minimum for entropy generation number and a maximum for ECOP at each Rayleigh number.

MHD natural convection in a semi-annulus enclosure filled with water-based nanofluid using DRBEM

Natural convection of a water-based nanofluid consisting Cu nanoparticles in a semi-annulus enclosure subjected to a magnetic field is considered. The inner wall has constant heat flux, the outer wall is maintained at a cold temperature and the other two walls are thermally insulated. The governing equations derived by considering the effect of magnetic field are solved numerically using the dual reciprocity boundary method (DRBEM) with constant elements. The boundary only nature of the dual reciprocity method results in considerably small computational cost in obtaining the solution. The simulations focus on the effects of the Rayleigh number, the Hartmann number, the nanoparticle volume fraction, and the inclination angles of the enclosure and the magnetic field on the flow and heat transfer characteristics. The results show that the convection and the average Nusselt number (Nu¯) decrease with an increase in the strength of the magnetic field whereas they increase by increasing the Rayleigh number. Furthermore, an increase in Hartmann number accelerates the rate of decrease in Nu¯ as inclination angles decrease. Thus, the inclined magnetic field and the inclination angle of the enclosure can be used as control parameters for enhancing the heat transfer convection and flow behavior in an enclosure.

Viscoelastoplastic bodies under cyclic loading in thermal-radiation fields

Deformation of viscoelastoplastic bodies in the neutron and thermal fluxes under a one-time loading has been studied previously in [1–3]. A mathematical model has been set forth in [4] for a cyclic deformation of elastoplastic bodies in a neutron flux. In the paper [5,6] ferrofluid flow and heat transfer in a semi annulus enclosure is investigated considering thermal radiation. This article [7] explores the effect of thermal radiation on Al2O3–water nanofluid flow and heat transfer in an enclosure with a constant flux heating element. In the article [8], effect of thermal radiation on magnetohydrodynamics nanofluid flow between two horizontal rotating plates is studied. In the study [8], heat and mass transfer characteristic of unsteady nanofluid flow between two parallel plates is investigated considering thermal radiation.This study considers the process of a combined effect of the heat, radiation and force cyclic loads on a viscoelastoplastic laminated body within the frames of the theory of small elastoplastic deformations.

Electrohydrodynamic free convection heat transfer of a nanofluid in a semi-annulus enclosure with a sinusoidal wall

ABSTRACTNatural convection heat transfer of a nanofluid in the presence of an electric field is investigated. The control volume finite element method (CVFEM) is utilized to simulate this problem. A Fe3O4–ethylene glycol nanofluid is used as the working fluid. The effect of the electric field on nanofluid viscosity is taken into account. Numerical investigation is conducted for several values of Rayleigh number, nanoparticle volume fraction, and the voltage supplied. The numerical results show that the voltage used can change the flow shape. The Coulomb force causes the isotherms to become denser near the bottom wall. Heat transfer rises with increase in the voltage supplied and Rayleigh number. The effect of electric field on heat transfer is more pronounced at low Rayleigh numbers due to the predomination of the conduction mechanism.

Effect of non-uniform magnetic field on forced convection heat transfer ofFe3O4–water nanofluid

In this paper force convection heat transfer in a lid driven semi annulus enclosure is studied in presence of non-uniform magnetic field. The enclosure is filled with Fe3O4–water nanofluid. It is assumed that the magnetization of the fluid is varying linearly with temperature and magnetic field intensity. Control volume based finite element method is used to solve the governing equations in the form of vorticity–stream function formulation. The calculations were performed for different governing parameters namely, the Reynolds number, nanoparticle volume fraction and Hartmann number. Results show that Nusselt number has direct relationship with Reynolds number, nanoparticle volume fraction while it has reverse relationship with Hartmann number.

Ferrofluid flow and heat transfer in a semi annulus enclosure in the presence of magnetic source considering thermal radiation

In this paper, ferrofluid flow and heat transfer in a semi annulus enclosure is investigated considering thermal radiation. The enclosure has a wall with constant heat flux boundary condition. Combined effects of Ferrohydrodynamic (FHD) and magnetohydrodynamic (MHD) are considered. It is assumed that the magnetization of the fluid is varying linearly with temperature and magnetic field intensity. Control Volume based Finite Element Method (CVFEM) is applied to solve the governing equations. The calculations were performed for different governing parameters namely; the Radiation parameter, Rayleigh number, nanoparticle volume fraction, Magnetic number arising from FHD and Hartmann number arising from MHD. Results show that Nusselt number is an increasing function of Rayleigh number, nanoparticle volume fraction, magnetic number while it is a decreasing function of with Hartmann number and radiation parameter.

Ferrohydrodynamic and magnetohydrodynamic effects on ferrofluid flow and convective heat transfer

In this paper, influence of an external magnetic field on ferrofluid flow and heat transfer in a semi annulus enclosure with sinusoidal hot wall is investigated. The governing equations which are derived by considering the both effects of FHD (Ferrohydrodynamic) and MHD (Magnetohydrodynamic) are solved via CVFEM (Control Volume based Finite Element Method). The effects of Rayleigh number, nanoparticle volume fraction, Magnetic number arising from FHD and Hartmann number arising from MHD on the flow and heat transfer characteristics have been examined. Results show that Nusselt number increases with augment of Rayleigh number and nanoparticle volume fraction but it decreases with increase of Hartmann number. Magnetic number has different effect on Nusselt number corresponding to Rayleigh number. Also it can be found that for low Rayleigh number, enhancement in heat transfer is an increasing function of Hartmann number and decreasing function of Magnetic number while opposite trend is observed for high Rayleigh number.

Numerical investigation of MHD effects on Al2O3–water nanofluid flow and heat transfer in a semi-annulus enclosure using LBM

In this study, free convection heat transfer in a concentric annulus between a cold square and heated elliptic cylinders in presence of magnetic field is investigated. The square and elliptic cylinders are maintained at uniform temperatures and it is assumed that the walls are insulating magnetic field. Lattice Boltzmann method is applied to solve the governing equations. The effective thermal conductivity and viscosity of nanofluid are calculated by KKL (Koo–Kleinstreuer–Li) correlation. In this model effect of Brownian motion on the effective thermal conductivity is considered. The numerical investigation is carried out for different governing parameters namely; the Hartmann number, Rayleigh number and nanoparticle volume fraction. Also a correlation of Nusselt number corresponding to active parameters is presented. The results reveal that average Nusselt number is an increasing function of nanoparticle volume fraction and Rayleigh number, while it is a decreasing function of Hartmann number. Moreover it can be found that the enhancement in heat transfer increases as Hartmann number increases but it decreases with increase of Rayleigh number.

Natural convection heat transfer in a nanofluid filled semi-annulus enclosure

To investigate natural convection heat transfer in a semi-annulus enclosure filled with nanofluid, the Control Volume based Finite Element Method (CVFEM) is used. The fluid in the enclosure is Cu–water nanofluid. The inner and outer semi circular walls are maintained at constant temperatures while the two other walls are thermally insulated. The Navier Stokes equations in their vorticity-stream function form are used to simulate the flow pattern and isotherms. The numerical investigation is carried out for different governing parameters namely; the Rayleigh number, nanoparticle volume fraction and the angle of turn for the enclosure. The effective thermal conductivity and viscosity of nanofluid are calculated using the Maxwell–Garnetts (MG) and Brinkman models, respectively. The results reveal that there is an optimum angle of turn in which the average Nusselt number is maximum for each Rayleigh number. Moreover, the angle of turn has an important effect on the streamlines, isotherms and maximum or minimum values of local Nusselt number.