Abstract
The present study investigates the role of natural and mixed convection heat transfer of a Cu–water nanofluid in a square cavity with inside circular heating and cooling bodies. The finite volume discretization method with the Semi-Implicit Method for Pressure Linked Equations algorithm is employed for solving the two-dimensional Navier–Stokes and energy equations. The effects of various design parameters on the heat transfer rate are investigated. Design parameters used in this numerical simulation are the position and size of circular bodies. A wide range of parameters such as the Rayleigh number (103 ≤ Ra ≤ 106 ), volume fraction (0 ≤ ϕ ≤ 0.05), Richardson number (0.01 ≤ Ri ≤ 1000), and the Grashof number (102 ≤ Gr ≤ 104 ) has been used. The numerical analysis is carried out for the circular body’s positions on the vertical centerline of the cavity. The circular body’s positions on the vertical left-line of the cavity are also presented and discussed for comparison purposes. The results show that the optimal heat transfer is obtained when placing the circular body near the bottom wall. Furthermore, the effects of pair of circular bodies on the heat transfer rate are investigated. The simulations show that the heat transfer rate increases with changing the orientation of the pair of circular bodies from the horizontal to the vertical directions. For the case of the mixed convection process, it is found that at high Richardson numbers, the effect of moving walls decreases and the heat transfer rate changes significantly.
Highlights
Natural and mixed convection fluid flow and heat transfer is very important phenomenon for various engineering applications, such as heating and cooling nuclear systems of reactors, lubrication technologies, cooling of electronic devices, ventilation of rooms with radiators, cooling of containers and heat exchangers [1]
5.1 natural convection (NC) configuration 5.1.1 Position of circular body The streamlines and isotherms corresponding to the position of the circular heating body on the vertical centerline (VC) of the cavity are presented in Figure 3 for which the Rayleigh
The circular heating body is fixed on the VC of the cavity and its position is changed from bottom to top (Y = 0.25, 0.5 and 0.75) at different Rayleigh numbers and volume fractions of nanoparticles
Summary
Natural and mixed convection fluid flow and heat transfer is very important phenomenon for various engineering applications, such as heating and cooling nuclear systems of reactors, lubrication technologies, cooling of electronic devices, ventilation of rooms with radiators, cooling of containers and heat exchangers [1]. 8.751 1032 insulated walls [4] and subjected to external convection [5] in the range of Rayleigh numbers between 104 and 107 They considered cases where the heater was positioned higher than the cooler and found that by increasing the gap between the HAC, the rate of heat transfer decreases. Boulahia et al [17] reported a MC of the nanofluids in two-sided liddriven square cavity with a pair of triangular heating cylinders They found that by reducing the diameter of the nanoparticles and Richardson number, the heat transfer rate increases, and by changing horizontal direction of the moving walls the heat transfer rate variation is negligible. Our numerical results are presented in the form of plots of isotherms, streamlines and average Nusselt numbers to show the influence of nanofluid and design parameters
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