Abstract
This article utilizes the finite volume method to solve the problem incorporating rarefied flow and heat transfer characteristics inside concaved cavities. Cavities are used in many applications, one of which is building insulation to reduce heat loss from walls. In this article, the influence of the aspect ratio ( B/ H), the tilt angle ( θ), Knudsen number ( Kn), and Rayleigh number ( Ra) on these characteristics were studied. Parameters ranges were [Formula: see text]. This study shows that the average Nusselt number ( Nu) decreases as the B/H and Kn increase. Whereas, Nu increases with increasing Ra. In addition, the Nu increases as θ increases to a given critical angle (60°), and beyond this angle, Nu decreases with increasing Ra. A new correlation of Nu including all parameters investigated in this work is introduced. This study reveals that concaved cavities could be used as thermal insulation bodies.
Highlights
Natural convection mode of heat transfer found in enclosures of different geometries is of importance to many engineering researchers due to its broad applications, such as those found in nuclear reactors and solar energy collectors
Terekhov et al.[1] numerically studied using Navier–Stokes and energy equations and Boussinesq approximation of laminar free convection flow and heat transfer inside a cavity that consists of two vertical parallel isothermal walls; the studied channel was equipped with two thin adiabatic fins on its walls
Using finite volume method (FVM), Sahi et al.[2] conducted a numerical investigation using FVM and Boussinesq approximation of the magnetic field effect on free convection heat transfer induced by two-dimensional buoyancy effect between two different top and bottom walls’ temperatures inside a rectangular grooved cavity subjected to isothermal walls
Summary
Natural convection mode of heat transfer found in enclosures of different geometries is of importance to many engineering researchers due to its broad applications, such as those found in nuclear reactors and solar energy collectors. They concluded that the SBT algorithm accurately predicts the wall heat flux by decreasing the average number of particles per cell to one particle or even less This is valid for a given constant Dx/Dt. Rana et al.[12] numerically investigated the steady flow and heat transfer characteristics of a twodimensional square cavity that contains rarefied argon gas with the heated bottom wall using Navier–Stokes– Fourier equations and the regularized 13 moments (R13) equations. Dadzie and Christou[13] investigated the rarefied gas heat transfer inside a lid-driven cavity flow induced by promptly heating and cooling opposite walls for various flow regimes They simulated the flows using a volume diffusion model as standard Navier–Stokes–Fourier extension. Few studies were conducted to investigate the effect of curved walls on rarefied flow and heat transfer characteristics inside wavy and concaved geometries. Colin[25] reported the slip condition and temperature jump at the interfaces between fluid and solid walls in cavities as follows
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