Direct numerical simulation of natural convection between an enclosure and multiple circular cylinders: An influence of horizontal arrangement of cylinders

The work involves a three-dimensional numerical analysis of the buoyancy-driven heat transfer in an enclosure having four heated cylinders for Rayleigh number, Ra = 10⁴-10⁶, and Prandtl number, Pr = 0.7. An in-house direct numerical simulation code, finite volume-based immersed boundary method incorporates the inner cylinder's virtual wall boundary and computes the governing transport equations. Heat and flow characteristics at different Ra and spacing between cylinders are discussed by using three-dimensional vortices and isotherms. The effect of heat and flow on three-dimensionality and heat transfer features are captured and reported. Limitations of two-dimensional simulation for capturing the physics of the problem and the importance of the three-dimensional analysis for the present study are highlighted.