Syeda Humaira Tasnim, Shohel Mahmud and Prodip Kumar Das
This paper presents the hydrodynamic and thermal behavior of fluid that surrounds an isothermal circular cylinder in a square cavity. Simulations were carried out for four aspect…
Abstract
This paper presents the hydrodynamic and thermal behavior of fluid that surrounds an isothermal circular cylinder in a square cavity. Simulations were carried out for four aspect ratios (defined by L/D), i.e. 2.0, 3.0, 4.0, 5.0. An incompressible flow of Newtonian fluid is considered. Prandtl number is assumed constant and equal to 1. Effect of eccentric positions (ε=−0.5 and 0.5) of the cylinder with respect to the cavity was carried out at L/D=2.0. Predicted results for eccentric cases are compared with concentric (ε=0.0) case. Grashof number is based on the diameter of the cylinder and ranges from 10 to 106. The control volume based finite volume method is used to discretize the governing equations in cylindrical coordinate. SIMPLE algorithm is used. A collocated variable arrangement is considered and SIP solver is employed to solve the system of equations. Parametric results are presented in the form of streamlines and isothermal lines for both eccentric and concentric positions. Heat transfer distribution along the perimeter of the cylinder is presented in the form of local Nusselt number. Predicted results show good agreement with the results described by Cesini et al. (1999).
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Prodip Kumar Das, Shohel Mahmud, Syeda Humaira Tasnim and A.K.M. Sadrul Islam
A numerical simulation has been carried out to investigate the buoyancy induced flow and heat transfer characteristics inside a wavy walled enclosure. The enclosure consists of…
Abstract
A numerical simulation has been carried out to investigate the buoyancy induced flow and heat transfer characteristics inside a wavy walled enclosure. The enclosure consists of two parallel wavy and two straight walls. The top and the bottom walls are wavy and kept isothermal. Two straight‐vertical sidewalls are considered adiabatic. Governing equations are discretized using the control volume based finite‐volume method with collocated variable arrangement. Simulation was carried out for a range of surface waviness ratios, λ=0.00‐0.25; aspect ratios, A=0.25‐0.5; and Rayleigh numbers Ra=100‐107 for a fluid having Prandtl number equal to 1.0. Results are presented in the form of local and global Nusselt number distributions, streamlines, and isothermal lines for different values of surface waviness and aspect ratios. For a special case of λ=0 and A=1.0, the average Nusselt number distribution is compared with available reference. The results suggest that natural convection heat transfer is changed considerably when surface waviness changes and also depends on the aspect ratio of the domain. In addition to the heat transfer results, the heat transfer irreversibility in terms of Bejan number (Be) was measured. For a set of selected values of the parameters (λ, A, and Ra), a contour of the Bejan number is presented at the end of this paper.