scholarly journals Computational Analysis of Heat Transfer Intensification of Fractional Viscoelastic Hybrid Nanofluids

2021 ◽  
Vol 2021 ◽  
pp. 1-24
Author(s):  
Mumtaz Khan ◽  
Amer Rasheed
Keyword(s):  
Heat Transfer ◽  
Boundary Conditions ◽  
Electric Fields ◽  
Computational Analysis ◽  
Numerical Solutions ◽  
Numerical Technique ◽  
Fluid Motion ◽  
Convection Heat Transfer ◽  
Point Of View ◽  
Hybrid Nanofluid

In the current article, we have performed computational analysis on convection heat transfer of a hybrid nanofluid in occurrences where porous media and the effect of magnetic force are involved. In order to assess the time-fractional derivatives, Caputo’s notion is utilized while the Darcy–Forchheimer model is applied due to the involvement of the porous medium. Moreover, the boundary conditions are assumed to be nonuniform through the equilibrium between the surface tension and shear stress over a semi-infinite permeable flat surface. Keeping in view the complexity of the fractional derivative model and nonuniform boundary conditions, the problem in question is a complicated one. Accordingly, the coupled momentum and energy equation is linearized and the finite difference scheme is then applied and implemented in MATLAB Code R2020b. Furthermore, we have also offered a comprehensive analysis regarding error and convergence of the proposed numerical method. The newly introduced numerical technique to determine the numerical solutions and some unique and interesting deductions are established. From the computational results, one can conclude that the fluid motion in both hybrid and single nanofluids slows down due to magnetic field, porosity, and inertia coefficient as the magnetic and electric fields are synchronized due to the formation of the Lorentz force and viscous interference. We believe that our proposed numerical technique regarding employment of the fractional model for heat transfer application to the hybrid nanofluid over a semi-infinite nonuniform permeable surface along with variable heat flux is not found in the literature so far. Furthermore, the obtained results will be a valuable addition to fractional calculus from an engineering point of view.

The Uncertainties of Continuum-Based CFD Solvers to Perform Microscale Hot-Wire Anemometer Simulations in Flow Fields Close to Transitional Regime

2016 ◽  
Author(s):  
Masoud Darbandi ◽  
Mohammad Reza Ghorbani ◽  
Hamed Darbandi
Keyword(s):  
Heat Transfer ◽  
Numerical Solutions ◽  
Stokes Equations ◽  
Slip Flow ◽  
Convection Heat Transfer ◽  
Flow Fields ◽  
Transitional Flow ◽  
Hot Wire ◽  
Fixed Temperature ◽  
Cfd Method

In this study, we simulate the flow and heat transfer during hot-wire anemometry and investigate its thermal behavior and physics using the Computational Fluid Dynamics (CFD) tool. In this regard, we use the finite-volume method and solve the compressible Navier-Stokes equations numerically in slightly non-continuum flow fields. We do not use any slip flow model to include the transitional flow physics in our simulations. Using the CFD method, we simulate the flow over hot–wire and evaluate the uncertainty of CFD in thermal simulation of hot-wire in low transitional flow regimes. The domain sizes and the mesh distributions are carefully chosen to avoid boundary condition error appearances. Following the past researches, we do not take into account the conduction heat transfer passing through hot-wire mounting arms in our simulations. Imposing a fixed temperature condition at the face of hot-wire, we simulate the flow over and the heat transfer from hot-wire and calculate the convection heat transfer coefficient and the local Nusselt number values. To be sure of the accuracy of our CFD code, we simulate a number of similar test cases and compare our numerical solutions with the available numerical solutions and/or experimental data.

Three Dimensional Numerical Simulation of the Natural Convection in an Annulus With an Internal Slotted Cylinder

2011 ◽  
Author(s):  
Mo Yang ◽  
Jin Wang ◽  
Kun Zhang ◽  
Ling Li ◽  
Yuwen Zhang
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Numerical Solutions ◽  
Three Dimensional ◽  
Convection Heat Transfer ◽  
Natural Convection Heat Transfer ◽  
Dimensional Model ◽  
Heat Transfer Characteristics ◽  
Flow And Heat Transfer ◽  
Rayleigh Numbers

Detailed numerical analysis is presented for three-dimensional natural convection heat transfer in annulus with an internal concentric slotted cylinder. The internal slotted cylinder and the outer annulus are maintained at uniform but different temperatures. Governing equations are discretized using control volume technique based on staggered grid formulation and solved using SIMPLE algorithm with QUICK scheme. Flow and heat transfer characteristics are investigated for a Rayleigh number range of 10 to 106 while Prandtl number (Pr) is taken to be 0.7. The results indicate, at Rayleigh numbers below 105, the system shows two dimensional flow and heat transfer characteristics. On the other hand, the flow and heat transfer shows three dimensional characteristics while for Rayleigh numbers greater than 5×105. Comparison with experimental results indicated that the numerical solutions by three dimensional model can obtain more accuracy than the numerical solutions by two dimensional model. Besides, Numerical results show that the average equivalent conductivity coefficient of natural convection heat transfer of this problem can be enhanced by as much as 30% while relative slot width is more than 0.1.

scholarly journals Free convection heat transfer of MgO-MWCNTs/EG hybrid nanofluid in a porous complex shaped cavity with MHD and thermal radiation effects

2019 ◽  
Vol 29 (11) ◽  
pp. 4349-4376 ◽  
Author(s):  
Mohammad Ghalambaz ◽  
Mahmoud Sabour ◽  
Ioan Pop ◽  
Dongsheng Wen
Keyword(s):  
Magnetic Field ◽  
Heat Transfer ◽  
Porous Medium ◽  
Complex Shape ◽  
Convection Heat Transfer ◽  
Hybrid Nanofluid ◽  
Convection Heat ◽  
Governing Equations ◽  
Content Type ◽  
Hybrid Nanofluids

Purpose The present study aims to address the flow and heat transfer of MgO-MWCNTs/EG hybrid nanofluid in a complex shape enclosure filled with a porous medium. The enclosure is subject to a uniform inclined magnetic field and radiation effects. The effect of the presence of a variable magnetic field on the natural convection heat transfer of hybrid nanofluids in a complex shape cavity is studied for the first time. The geometry of the cavity is an annular space with an isothermal wavy outer cold wall. Two types of the porous medium, glass ball and aluminum metal foam, are adopted for the porous space. The governing equations for mass, momentum and heat transfer of the hybrid nanofluid are introduced and transformed into non-dimensional form. The actual available thermal conductivity and dynamic viscosity data for the hybrid nanofluid are directly used for thermophysical properties of the hybrid nanofluid. Design/methodology/approach The governing equations for mass, momentum and heat transfer of hybrid nanofluid are introduced and transformed into non-dimensional form. The thermal conductivity and dynamic viscosity of the nanofluid are directly used from the experimental results available in the literature. The finite element method is used to solve the governing equations. Grid check procedure and validations were performed. Findings The effect of Hartmann number, Rayleigh number, Darcy number, the shape of the cavity and the type of porous medium on the thermal performance of the cavity are studied. The outcomes show that using the composite nanoparticles boosts the convective heat transfer. However, the rise of the volume fraction of nanoparticles would reduce the overall enhancement. Considering a convective dominant regime of natural convection flow with Rayleigh number of 107, the maximum enhancement ratio (Nusselt number ratio compared to the pure fluid) for the case of glass ball is about 1.17 and for the case of aluminum metal foam is about 1.15 when the volume fraction of hybrid nanoparticles is minimum as 0.2 per cent. Originality/value The effect of the presence of a variable magnetic field on the natural convection heat transfer of a new type of hybrid nanofluids, MgO-MWCNTs/EG, in a complex shape cavity is studied for the first time. The results of this paper are new and original with many practical applications of hybrid nanofluids in the modern industry.

Natural Convection Heat Transfer of Water Within a Horizontal Cylindrical Annulus With Density Inversion Effects

1983 ◽  
Vol 105 (1) ◽  
pp. 117-123 ◽  
Author(s):  
P. Vasseur ◽  
L. Robillard ◽  
B. Chandra Shekar
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Numerical Solutions ◽  
Cold Water ◽  
Freezing Point ◽  
Convection Heat Transfer ◽  
Natural Convection Heat Transfer ◽  
Convection Heat ◽  
Density Inversion ◽  
Cylindrical Annulus

The effect of density inversion on steady natural convection heat transfer of cold water, between two horizontal concentric cylinders of gap width, L, is studied numerically. Water near its freezing point is characterized by a density maximum at 4°C. Numerical solutions are obtained for cylinders with nonlinear Rayleigh numbers RA ranging from 2 × 103 to 7.6 × 104, a radius ratio 1.75 ≤ ra ≤ 2.6 and an inversion parameter γ, relating the temperature for maximum density with the cavity wall temperatures, between −2 and 2. The results obtained are presented graphically in the form of streamline and isotherm contour plots. The heat transfer characteristics, velocity profiles, and local and overall Nusselt numbers are studied. The results of the present study were found qualitatively valid when compared with an experimental investigation carried out in the past.

A note on the solution of transient dispersion problems

1967 ◽  
Vol 298 (1454) ◽  
pp. 335-339 ◽  
Keyword(s):  
Heat Transfer ◽  
Laminar Flow ◽  
Boundary Conditions ◽  
Forced Convection ◽  
Convection Heat Transfer ◽  
General Boundary Conditions ◽  
Convection Heat ◽  
Forced Convection Heat Transfer ◽  
Transient Dispersion ◽  
Mass Dispersion

A solution is developed for the problem of transient mass dispersion in fully developed laminar flow in a tube. The method can be extended to more general geometries, and by superposition to include more general boundary conditions such as those which occur in forced convection heat transfer.

Natural Convection Heat Transfer From a Plate in a Semicircular Enclosure

1992 ◽  
Vol 114 (1) ◽  
pp. 121-126 ◽  
Author(s):  
G. A. Moore ◽  
K. G. T. Hollands
Keyword(s):  
Heat Transfer ◽  
Natural Convection ◽  
Rayleigh Number ◽  
Plate Thickness ◽  
Fluid Motion ◽  
Convection Heat Transfer ◽  
Bulk Fluid ◽  
Number Range ◽  
Balance Technique ◽  
Conductive Component

In the subject geometry, a long thin plate at uniform temperature is contained coaxially and symmetrically in a long semicircular trough closed at the top and having a uniform but different temperature. Heat flows across the air-filled region between the two by both natural convection and gaseous conduction. The problem of characterizing the free convective component of this heat transfer—that is, the component caused by bulk fluid motion—is treated experimentally by using a heat balance technique, with the measurements being repeated at different pressures, in order to cover a wide Rayleigh number range, from Ra ≈ 10 to Ra ≈ 108. Nusselt number versus Rayleigh number plots are presented for each of several combinations of plate-to-trough spacing and tilt angle, and the plots are correlated by equations. The problem of characterizing the conductive component is treated by numerically solving the steady diffusion equation in the air-filled region, and the results are correlated as a function of the spacing and the plate thickness.

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