Laminar Mixed Convection in Inclined Triangular Enclosures Filled with Water Based Cu Nanofluid (original) (raw)
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Journal of Computational and Theoretical Nanoscience, 2013
This paper examines the thermal and flow fields characteristics of laminar steady mixed convection flow in a rectangular inclined lid-driven cavity filled with water-based nanofluids numerically using finite difference method. Whilst a uniform heat source is located on a part of the left inclined sidewall of the cavity, the right inclined sidewall is considered adiabatic together with the remain parts of the left inclined sidewall. The top and bottom walls are maintained at a relatively low temperature and the top wall moves from left to right with uniform lid-driven velocity. The fluid inside the cavity is a water based nanofluid containing different types of solid spherical nanoparticles: Cu, Ag, Al203, and Ti02• Based on the numerical simulation, the effects of the dominant parameters such as Richardson number, cavity inclination angle, solid volume fraction, heat source effect and type of nanoparticles are examined. The numerical results are obtained for inclination angles ranging from 0° to 90°, for Reynolds numbers varying from 1 to 100 and for the solid volume fractions varying from 0% to 20%. Comparisons with previously published numerical works on mixed convection in a nanofluid filled cavity are performed and good agreements between the results are observed. It is found that the local Nusselt number is seen to decrease as the inclination angle and solid volume fraction increase. Also, the results of the present study indicate that the presence of nanoparticles in the fluid is found to alter the structure of the fluid flow. Moreover, it is observed that the shape of the circulation vortex is sensitive to the inclination angle and addition of nanofluids.
Mixed convection flow in a lid-driven inclined square enclosure filled with a nanofluid
This work is focused on the numerical modeling of steady laminar mixed convection flow in a lid-driven inclined square enclosure filled with water–Al 2 O 3 nanofluid. The left and right walls of the enclosure are kept insulated while the bottom and top walls are maintained at constant temperatures with the top surface being the hot wall and moving at a constant speed. The developed equations are given in terms of the stream function–vorticity formulation and are non-dimensionalized and then solved numerically subject to appropriate boundary conditions by a second-order accurate finite-volume method. Comparisons with previously published work are performed and found to be in good agreement. A parametric study is conducted and a set of graphical results is presented and discussed to illustrate the effects of the presence of nanoparticles and enclosure inclination angle on the flow and heat transfer characteristics. It is found that significant heat transfer enhancement can be obtained due to the presence of nanoparticles and that this is accentuated by inclination of the enclosure at moderate and large Richardson numbers.
International Journal of Engineering, 2011
The buoyancy-driven fluid flow and heat transfer in a square cavity with partially active side walls filled with Cu-water nanofluid is investigated numerically. The active parts of the left and the right side-walls of the cavity are maintained at temperatures T h and T c , respectively, with T h >T c. The enclosure's top and bottom walls, as well as, the inactive parts of its side walls are kept insulated. The governing equations are discretized using the finite volume method and the hybrid scheme. Using the developed code, a parametric study is undertaken and the effects of the Rayleigh number, the locations of the active parts of the side walls, the volume fraction of nanoparticles, and inclination angle of cavity on the fluid flow and heat transfer inside the cavity are investigated. It is observed from the results that the average Nusselt number increases with increasing both the Rayleigh number and the volume fraction of the nanoparticles. Moreover, the maximum average Nusselt number occurs for the middle-middle location of the thermally active parts.
International Journal of Modern Physics C, 2019
This paper discusses the results of a study related to natural convection cooling of a heat source located on the bottom wall of an inclined isosceles triangular enclosure filled with a Cu water-nanofluid. The right and left walls of the enclosure are both maintained cold at constant equal temperatures, while the remaining parts of the bottom wall are insulated. The study has been carried out for a Rayleigh number in the range 10 4 B Ra B 10 6 , for a heat source length in the range 0.2 B e B0.8, for a solid volume fraction in the range 0 B /B0.06 and for an inclination angle in the range 0°B dB45°. Results are presented in the form of streamline contours, isotherms, maximum temperature at the heat source surface and average Nusselt number. It is noticed that the addition of Cu nanoparticles enhances the heat transfer rate and therefore cooling effectiveness for all values of Rayleigh number, especially at low values of Ra. The effect of the inclination angle becomes more noticeable as one increases the value of Ra. For high Rayleigh numbers, a critical value for the inclination angle of d = 15°is found for which the heat source maximum temperature is highest.
Arabian Journal for Science and Engineering, 2017
The present paper reports a numerical investigation of steady and laminar mixed convection flow within an irregular ventilated enclosure, crossed by Cu-Water nanofluid. The bottom wall is maintained at a constant and uniform temperature, whereas the top and the vertical walls are adiabatic. The inclined wall as well as the nanofluid at the entrance is kept at a lower constant temperature. The governing coupled equations are resolved by the means of the finite volume technique. The computations are performed using a homemade computer code, which was successfully validated, after comparison of our results with pervious numerical and experimental works. Empirical relations to predict the nanofluid's effective thermal conductivity and viscosity were employed. The results are analyzed through dynamic and thermal fields with a particular attention to the Nusselt number evaluated along the active wall. The results reveal that the flow structure is more sensitive to both Richardson and Reynolds numbers variations. Moreover, heat transfer is enhanced by the increase in the nanoparticles volume fraction, Richardson and Reynolds numbers and by the decrease in the nanoparticles diameter. Useful correlations predicting the heat transfer rate as a function of nanoparticles volume fraction and diameter as well as the Richardson number are proposed.
Heat and Mass Transfer, 2013
This paper discusses the results of a study related to natural convection cooling of a heat source located on the bottom wall of an inclined isosceles triangular enclosure filled with a Cu water-nanofluid. The right and left walls of the enclosure are both maintained cold at constant equal temperatures, while the remaining parts of the bottom wall are insulated. The study has been carried out for a Rayleigh number in the range 10 4 B Ra B 10 6 , for a heat source length in the range 0.2 B e B0.8, for a solid volume fraction in the range 0 B /B0.06 and for an inclination angle in the range 0°B dB45°. Results are presented in the form of streamline contours, isotherms, maximum temperature at the heat source surface and average Nusselt number. It is noticed that the addition of Cu nanoparticles enhances the heat transfer rate and therefore cooling effectiveness for all values of Rayleigh number, especially at low values of Ra. The effect of the inclination angle becomes more noticeable as one increases the value of Ra. For high Rayleigh numbers, a critical value for the inclination angle of d = 15°is found for which the heat source maximum temperature is highest.
Applied Mathematical Modelling, 2014
In the present work, two-dimensional mixed convection fluid flow and heat transfer of water-(Cu, Ag, Al 2 O 3 and TiO 2 ) nanofluids in a two-sided facing lid-driven cavity partially heated from below have been investigated numerically. Two discrete heat sources are located on the bottom wall of the enclosure; however, the vertical moving walls and the ceiling are cooled at constant temperature. The remaining boundary parts of the bottom wall are kept insulated. The flow is driven by the moving two facing vertical walls in the same direction and the buoyancy force. The governing equations are solved using a second order accurate finite volume approach. The effects of the monitoring parameters in given ranges such as Reynolds ð1 6 Re 6 100Þ and Richardson numbers ð1 6 Ri 6 20Þ, solid volume fraction ð0 6 u 6 0:2Þ, the nanoparticles materials as well as the two heat sources positions are investigated. The conducted benchmark study leads to excellent accordance with previous findings. The present study analyzes and discusses the flow patterns (streamlines structures and isotherms distributions) set up by the competition between the forced flow driven by the moving walls and the buoyancy force effects, and the heat transfer rate quantified by the averaged Nusselt number along the heat source. It was found that significant heat transfer enhancement can be obtained: (i) increasing Ri at high Reynolds number (Re = 100) results in up-to 20% augmentation of heat transfer rate for all Cu volume fractions; (ii) increasing the volume fraction u, a maximum heat transfer rate increase of 47.010% is reached with Cu suspensions for u = 0.2 and Ri = 1, while a minimum increase of 7.059% is observed for TiO 2 -water nanofluid at Ri = 10 and u = 0.05; (iii) a highest heat transfer enhancement occurs when heat sources move toward the two vertical moving walls, while a lower heat transfer is obtained for heat sources located at bottom wall center.
A numerical analysis is performed to examine laminar mixed convection cooling of a constant heat flux at the bottom wall of a square enclosure filled with water-base nanofluid containing various volume fractions of Cu, Ag, Al 2 O 3 and TiO 2. The finite difference method is employed to solve the dimensionless governing equations of the problem. The influences of the governing parameters, namely, Reynolds number, location and geometry of the heat source, the type of nanofluid and solid volume fraction of nanoparticles on the cooling performance are studied. The present results are validated by favorable comparisons with previously published results. The results of the problem are presented in graphical and tabular forms and discussed.
Effects of inclination angle on natural convection in enclosures filled with Cu–water nanofluid
International Journal of Heat and Fluid Flow, 2009
Effects of inclination angle on natural convection heat transfer and fluid flow in a two-dimensional enclosure filled with Cu-nanofluid has been analyzed numerically. The performance of nanofluids is tested inside an enclosure by taking into account the solid particle dispersion. The angle of inclination is used as a control parameter for flow and heat transfer. It was varied from = 0°to = 120°. The governing equations are solved with finite-volume technique for the range of Rayleigh numbers as 10 3 6 Ra 6 10 5 . It is found that the effect of nanoparticles concentration on Nusselt number is more pronounced at low volume fraction than at high volume fraction. Inclination angle can be a control parameter for nanofluid filled enclosure. Percentage of heat transfer enhancement using nanoparticles decreases for higher Rayleigh numbers.
Heat transfer enhancement of mixed convection in an inclined porous cavity using Cu-water nanofluid
In this paper, mixed convection of Cu-nanofluid in an inclined fluid-saturated porous cavity is numerically analyzed by considering three different cases depending on the direction of moving wall(s). The equations of nanofluid-saturated porous medium can be derived by the Darcy-Brinkman-Forchheimer model and are solved using the SIMPLE algorithm. The effect of various non-dimensional parameter such as the Richardson number, Darcy number, inclination angle, solid volume fraction and three different cases are carefully analyzed. The obtained results are presented in the form of streamlines, isotherms, mid-height velocity profiles and average Nusselt number. It is found that the flow and heat transfer play a significant role with the direction of the moving wall(s).