Computational study on MHD power-law fluid in tilted enclosure having sinusoidal heated sidewall

2020 ◽  
Vol 16 (5) ◽  
pp. 1041-1059
Author(s):  
Minakshi Poonia
Keyword(s):  
Magnetic Field ◽  
Nusselt Number ◽  
Power Law ◽  
Inclination Angle ◽  
Average Nusselt Number ◽  
Computational Study ◽  
Convection Flow ◽  
Power Law Fluid ◽  
Left Wall ◽  
Content Type

PurposeIn the present computational study, the heat transfer and two-dimensional natural convection flow of non-Newtonian power-law fluid in a tilted rectangular enclosure is examined. The left wall of enclosure is subjected to spatially varying sinusoidal temperature distribution and right wall is cooled isothermally while the upper and lower walls are retained to be adiabatic. The flow is considered to be laminar, steady and incompressible under the influence of magnetic field. The governing mass, momentum and energy equations are transformed into dimensionless form in terms of stream function, vorticity and temperature.Design/methodology/approachThen resulted highly non-linear partial differential equations are solved computationally using Galerkin finite element method.FindingsThe exhaustive flow pattern and temperature fields are displayed through streamlines and isotherm contours for various parameters, namely, Prandtl number, Rayleigh number, Hartmann number by considering different power-law index and inclination angle. The effect of inclination angle on average Nusselt number is also shown graphically. This problem observes the potential vortex flow with elliptical core. The results show that the circular strength of the vortex formed reduces as the magnetic field strength grows. As the inclination angle increases the intensity of flow field decreases while the value of average Nusselt number increases.Originality/valueThis study has important applications in thermal management such as cooling techniques used in buildings, nuclear reactors, heat exchangers and power generators.

Impacts of variable magnetic field on a ferrofluid flow inside a cavity including a helix using ISPH method

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Abdelraheem M. Aly ◽  
Sameh Elsayed Ahmed ◽  
Zehba Raizah
Keyword(s):  
Magnetic Field ◽  
Nusselt Number ◽  
Average Nusselt Number ◽  
Volume Fraction ◽  
Heat Pumps ◽  
Variable Magnetic Field ◽  
Convection Flow ◽  
Content Type ◽  
Air Conditioners ◽  
Magnetic Source

Purpose The purpose of this paper is to study the unsteady ferrofluid flow with a hot source helix inside a cavity under the impacts of a variable magnetic field by using the incompressible smoothed particle hydrodynamics method. Design/methodology/approach The governing equations are formulated by considering the basics of the magnetohydrodynamic and ferrohydrodynamics. Different locations of a variable magnetic source outside the geometry are investigated. The helical coils are extensively applied in the cooling and heating of air conditioners and heat pumps. Computations were carried out for different lengths of the heated helix (0.2 ≤ Lh ≤ 0.8), different locations of the magnetic source, (a = 0.5, b = −0.01), (a = 0.5, b = 1.01), (a = 1.01, b = 0.5), (a = −0.01, b = 0.5), different numbers of the inner helix (one helix, two helixes and three helixes) and different values of the nanoparticles volume fraction (0% ≤ ϕ ≤ 10%). Findings The outcomes of the investigations revealed that an increase in the lengths of a helix by 0.4 results in a reduction of the stream function by 25.60%. In addition, when the magnetic wire is located near the center of the right wall, the maximum values of the average Nusselt number are obtained while the smallest values of the average Nusselt number are given when the magnetic source is located near center of the top wall. Originality/value The novelty of this paper is investigating the natural convection flow from two different models of an inner hot helix inside a cavity with considering different locations of variable magnetic sources.

Double Diffusive Marangoni Convection Flow of Electrically Conducting Fluid in a Square Cavity With Chemical Reaction

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
M. Saleem ◽  
M. A. Hossain ◽  
Suvash C. Saha
Keyword(s):  
Magnetic Field ◽  
Nusselt Number ◽  
Sherwood Number ◽  
Average Nusselt Number ◽  
Marangoni Convection ◽  
Convection Flow ◽  
Square Cavity ◽  
Electrically Conducting ◽  
Electrically Conducting Fluid ◽  
Double Diffusive

Double diffusive Marangoni convection flow of viscous incompressible electrically conducting fluid in a square cavity is studied in this paper by taking into consideration of the effect of applied magnetic field in arbitrary direction and the chemical reaction. The governing equations are solved numerically by using alternate direct implicit (ADI) method together with the successive over relaxation (SOR) technique. The flow pattern with the effect of governing parameters, namely the buoyancy ratio W, diffusocapillary ratio w, and the Hartmann number Ha, is investigated. It is revealed from the numerical simulations that the average Nusselt number decreases; whereas the average Sherwood number increases as the orientation of magnetic field is shifted from horizontal to vertical. Moreover, the effect of buoyancy due to species concentration on the flow is stronger than the one due to thermal buoyancy. The increase in diffusocapillary parameter, w causes the average Nusselt number to decrease, and average Sherwood number to increase.

MHD natural convection flow in cavities filled with square solid blocks

2014 ◽  
Vol 24 (8) ◽  
pp. 1813-1830 ◽  
Author(s):  
Majid Ashouri ◽  
Mohammad Behshad Shafii ◽  
Hossein Rajabi Kokande
Keyword(s):  
Magnetic Field ◽  
Thermal Conductivity ◽  
Nusselt Number ◽  
Natural Convection ◽  
Numerical Code ◽  
Thermal Conductivity Ratio ◽  
Convection Flow ◽  
Conductivity Ratio ◽  
Natural Convection Flow ◽  
Content Type

Purpose – The purpose of this paper is to study the influence of magnetic field on natural convection inside the enclosures partially filled with conducting square solid obstacles. Also, the effect of thermal conductivity ratio between the solid and fluid materials is investigated for different number of solid blocks. Design/methodology/approach – The dimensionless governing equations are transformed into sets of algebraic equations using finite volume method and momentum equations are solved by the SIMPLE algorithm with the hybrid scheme. The validation of the numerical code was conducted by comparing the results of average Nusselt number with previously published works. Findings – The results indicate that both the magnetic field and solid blocks can significantly affect the flow and temperature fields. It is shown that for a given Rayleigh number, variation of Nusselt number might be increasing or decreasing with change in solid-to-fluid thermal conductivity ratio depending on magnetic field strength and number of solid blocks. Originality/value – No work has been reported previously on the effect of magnetic field on natural convection flow in a cavity partially filled with square solid blocks. The numerical analysis of conductivity ratio between the solid and fluid materials under the effect of magnetic field have been carried out for the first time.

MHD heat transfer and entropy generation in inclined trapezoidal cavity filled with nanofluid

2017 ◽  
Vol 27 (10) ◽  
pp. 2174-2202 ◽  
Author(s):  
Kamel Milani Shirvan ◽  
Soroush Mirzakhanlari ◽  
Hakan F. Öztop ◽  
Mojtaba Mamourian ◽  
Khaled Al-Salem
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Sensitivity Analysis ◽  
Nusselt Number ◽  
Rayleigh Number ◽  
Entropy Generation ◽  
Inclination Angle ◽  
Effective Parameters ◽  
Content Type ◽  
The Mean

Purpose The main purpose of this paper is to define 2D numerical study and a sensitivity analysis of natural convection heat transfer and entropy generation of Al2O3-water nanofluid in a trapezoidal cavity, with considering of the presence of a constant axial magnetic field. Design/methodology/approach The effects of the three effective parameters, the Rayleigh number, Hartmann number (Ha) and also inclination angle on the heat transfer performance and entropy generation, are investigated using a finite volume approach. The sensitivity analysis of the effective parameters is done utilizing the response surface methodology. Findings The results obtained showed that the mean Nusselt number and total entropy generation increase with the Rayleigh number. Also, increasing the inclination angle reduces the mean Nusselt number (regardless of the magnetic field). In addition, it is found that the mean Nusselt number increases until Ha = 10 and then decreases by increasing of Ha number, regardless of the inclination angle. The sensitivity of the mean Nusselt number to the Ha number and inclination angle α is negative. It is concluded that to maximize the mean Nusselt number and minimize the entropy generation, simultaneously, the Ha and inclination angle must be 50° and 0°, respectively. Originality/value There is no published research in the literature about sensitivity analysis of magneto-hydrodynamic heat transfer and entropy generation in inclined trapezoidal cavity filled with nanofluid.

scholarly journals Laminar natural convection of non-Newtonian power-law fluid in an eccentric annulus

2019 ◽  
pp. 424-424
Author(s):  
Oussama Benhizia ◽  
Mohamed Bouzit ◽  
Ahmed Dellil
Keyword(s):  
Nusselt Number ◽  
Natural Convection ◽  
Power Law ◽  
Average Nusselt Number ◽  
Two Dimensional ◽  
Power Law Fluid ◽  
Eccentric Annulus ◽  
Nusselt Numbers ◽  
Laminar Natural Convection ◽  
Good Agreement

This work is about studying the natural convection of two-dimensional steady state non-Newtonian power law fluid numerically. The inner cylinder was put eccentrically into the outer one. The cylinders are held at constant temperatures with the inner one heated isothermally at temperature Th and the outer one cooled isothermally at temperature Tc (Th>Tc). The simulations have been taken for the parameters 103?Ra?105, 10?Pr?103, 0.6?n?1.4, 0???0.9 and an inclination angle ? from 0? up to 90?. The average Nusselt numbers for the previous parameters are obtained and discussed numerically. The results revealed that the average Nusselt number has the highest values when n=0.6, Ra=105 at ?=0 which is a signal for the large transfer herein and has the lowest values for n=1.4, Ra=103 at ?=90? which is a signal that the transfer is by conduction more than convection. Furthermore, the increasing of eccentricity causes an increase in the Nusselt number for all the cases. Finally, the best case where we can get the best heat transfer is at ? = 0, ?=0.9 among them all. The results have compared with some precedent works and showed good agreement.

Effects of uniform magnetic field on the natural convection of Cu–water nanofluid in a triangular cavity

2017 ◽  
Vol 27 (2) ◽  
pp. 334-357 ◽  
Author(s):  
T. Javed ◽  
Z. Mehmood ◽  
M.A. Siddiqui ◽  
Ioan Pop
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Nusselt Number ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Absorption Coefficient ◽  
Uniform Magnetic Field ◽  
Left Wall ◽  
Content Type ◽  
Nusselt Numbers

Purpose The purpose of this paper is to perform a numerical study for heat transfer through natural convection in the presence of a constant magnetic field in an incompressible steady nanofluid flow inside an isosceles triangular cavity. Design/methodology/approach For this flow problem, the left wall of the cavity subjected to uniform/nonuniform heat was considered, while right and bottom walls of the cavity were kept cold. The obtained equations were solved by using the Galerkin weighted residual technique. Results are computed for a wide range of parameters including Rayleigh number (Ra) (10^3 < Ra < 10^7), Hartman number (Ha) (0 < Ha < 60), and heat-generation/-absorption coefficient (q) (−10 < q < 10), while, Prandtl number (Pr) was kept fixed at 6.2. These computed results are presented in terms of stream functions, isotherms, Nusselt numbers and average Nusselt numbers through figures. Findings It is observed that, in case of uniform heating of the side wall, the strength of stream lines’ circulations increases with an increase in Ra and decreases with an increase in Ha. Similarly, by increasing heat-absorption coefficient q, an increase in the circulation strength is noted and the circulation cell moves towards the left wall in the presence of a heat sink (q < 0) and moves to the cold right wall in the presence of a heat source (q > 0). In the case of nonuniformly heated left wall in the presence of a heat source (q > 0), a higher-temperature gradient is observed in the cavity and isotherms are clustered to the left wall in the lower portion and to right wall in the upper portion; these appear to be straight and parallel to the x-axis near the bottom wall. On the other hand, the heat transfer rate along all the walls of the cavity is observed to be higher for smaller values of q. Whereas, Nusselt number along the bottom wall (Nu-B) increases with an increase in the values of x, while, that along the left wall (Nu-L) first increases and then decreases. But Nusselt number along the right wall (Nu-R) is found to be qualitatively opposite to Nu-L with an increase in distance x. Whereas, average Nusselt number increases with an increase in Rayleigh number Ra and heat-generation/-absorption coefficient q. Research limitations/implications The problem is formulated for an incompressible flow; viscous dissipation has been neglected, negligible induced magnetic field has been considered and local thermal equilibrium has been considered. Originality/value Results presented in this paper are original and new for the effects of a uniform magnetic field on the natural convection of Cu–water nanofluid in a triangular cavity. Hence, this study is important for researchers working in the area of heat transfer in cavity flows involving the nanofluid to become familiar with the flow behavior and properties.

Magnetohydrodynamic time-dependent computational natural convection flow, heat and mass transfer in inclined semi-circular enclosures

2016 ◽  
Vol 26 (8) ◽  
pp. 2310-2330 ◽  
Author(s):  
M.M. Rahman ◽  
Hakan F. Öztop ◽  
R. Saidur ◽  
A.G. Naim ◽  
Khaled S. Al-Salem ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Mass Transfer ◽  
Natural Convection ◽  
Heat And Mass Transfer ◽  
Inclination Angle ◽  
Time Dependent ◽  
Convection Flow ◽  
Natural Convection Flow ◽  
Content Type ◽  
Flow Heat

Purpose The purpose of this paper is to make a numerical analysis on unsteady analysis of natural convection heat and mass transfer to obtain flow field, temperature distribution, and concentration distribution. Design/methodology/approach A finite element method is applied to solve governing equations of natural convection in curvilinear-shaped system for different parameters as thermal Rayleigh numbers (103=RaT=106), inclination angle (0°=φ=60°) and Hartmann numbers (0=Ha=100). Findings Both magnetic field and inclination angle can be used as control parameter on heat and mass transfer. Flow strength decreases almost 100 percent between Ha=0 and Ha=100 on behalf of the higher values of thermal Rayleigh number. Originality/value The originality of this work is to application of magnetic field on time-dependent natural convection flow, heat and mass transfer for curvilinear geometry.

MHD-mixed convection flow in a lid-driven trapezoidal cavity under uniformly/non-uniformly heated bottom wall

2017 ◽  
Vol 27 (6) ◽  
pp. 1231-1248 ◽  
Author(s):  
T. Javed ◽  
Z. Mehmood ◽  
Ioan Pop
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Nusselt Number ◽  
Mixed Convection ◽  
Bottom Wall ◽  
Local Thermal Equilibrium ◽  
Convection Flow ◽  
Mixed Convection Flow ◽  
Content Type ◽  
Left And Right

Purpose The purpose of this paper is to analyze numerical results for heat transfer through mixed convection in an incompressible steady lid-driven fluid flow inside a trapezoidal cavity in the presence of a uniform magnetic field. Design/methodology/approach In this study, the authors have considered three different cases, in which left and right walls of the cavity are tilted at different angles of 0, 30 and 45 degrees, respectively. Both left and right side walls of the cavity are taken cold and the upper wall is insulated and assumed moving with constant speed, whereas the bottom wall is considered to be heated uniformly/non-uniformly. To eliminate pressure term, penalty method is applied to governing Navier–Stokes’ equations. The reduced equations are solved by Galerkin weighted residual technique of finite element method. Grid-independent results are obtained and shown in terms of plots for streamlines, isotherms, Nusselt number and average Nusselt number for a wide range of flow parameters, including Rayleigh numbers Ra, Prandtl number Pr and Hartman number Ha. Findings It has been observed that the effects of moving lid become negligible for Ra = 100,000, whereas increasing Rayleigh number results in stronger streamline circulation and convection dominant effects inside the enclosure. Local Nusselt number Nu along the bottom wall is observed to be maximum at edges and it reduces while moving toward the center from edges, and attains minimum value at the center of the bottom wall. Research limitations/implications The problem is modeled for laminar and incompressible flow, induced magnetic field has been considered negligibly small and local thermal equilibrium has been assumed. Originality/value In this investigation, the authors have presented new and original results for mixed convection flow inside a lid-driven trapezoidal cavity under the influence of a magnetic field. Hence, this study would be important for the researchers working in the area of heat transfer in cavity flows involving magnetic effects to become familiar with the flow behavior and properties.

Forced convection heat transfer study of a blunt-headed cylinder in non-Newtonian power-law fluids

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Jaspinder Kaur ◽  
Roderick Melnik ◽  
Anurag Kumar Tiwari
Keyword(s):  
Heat Transfer ◽  
Nusselt Number ◽  
Drag Coefficient ◽  
Power Law ◽  
Average Nusselt Number ◽  
Convection Heat Transfer ◽  
Convection Heat ◽  
Total Drag ◽  
Shear Thinning Fluids ◽  
Power Law Fluids

Abstract In this present work, forced convection heat transfer from a heated blunt-headed cylinder in power-law fluids has been investigated numerically over the range of parameters, namely, Reynolds number (Re): 1–40, Prandtl number (Pr): 10–100 and power-law index (n): 0.3–1.8. The results are expressed in terms of local parameters, like streamline, isotherm, pressure coefficient, and local Nusselt number and global parameters, like wake length, drag coefficient, and average Nusselt number. The length of the recirculation zone on the rear side of the cylinder increases with the increasing value of Re and n. The effect of the total drag coefficient acting on the cylinder is seen to be higher at the low value of Re and its effect significant in shear-thinning fluids (n < 1). On the heat transfer aspect, the rate of heat transfer in fluids is increased by increasing the value of Re and Pr. The effect of heat transfer is enhanced in shear-thinning fluids up to ∼ 40% and it impedes it’s to ∼20% shear-thickening fluids. In the end, the numerical results of the total drag coefficient and average Nusselt number (in terms of J H −factor) have been correlated by simple expression to estimate the intermediate value for the new application.

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