Study of the Impacts of Different Geometry and Aspect Ratio Hot Body on Natural Convection Heat Transfer

Abstract

This work deals with a two-dimensional laminar natural convection heat flow, based on the temperature difference between the cold outer corrugated cylinder and three different cross-sectional areas, i.e. circular, square, and triangle configuration at the steady-state condition. The free region between two surfaces has been filled by a fluid with (Pr=7.0), and CFD finite volume method has been employed to solve the main equations. The simulations have been performed based on the dimensionless parameters: (Ra=104-105-106), (D/Dbase, and L/Dbased), while θ=0°-90°-180° has been applied for square and triangle configuration. The results are displayed in terms of isothermal contours and stream function and the heat transfer is recognized by both local and average Nusselt number. Firstly, the ANSYS 19.2 code validation has been performed by the comparisons of the outer data with previously theoretical papers, and good agreements have been detected. It is initiated from the local and average Nusselt number that the heat transfer from the inner hot surface has been affected by the above governing parameters at a certain fixed value of Ra. In all the results of the valve of average Nu approximately constant for the same configuration when Ra<106 also, flow lines become fewer symmetrical when Ra=106. It is detected that both the cylinder aspect ratio and coordinations have a significant effect on the thermal fields and flow distribution. Moreover, the results that designate the changing of D/Dbase to 0.3 cause improvement in heat transfer by 23.3% at Ra=106, and also the circular cylinder is better than the other configurations.