Effect of a Two Cylinder Vertical Location on the Three-Dimensional Natural Convection Between a Parallel Channel

This study numerically investigated the effects of a two-cylinder vertical location on the three-dimensional natural convection in the space between a horizontal, parallel channel. Direct numerical simulations based on the finite volume method were performed for the Rayleigh numbers of 10(4) and 10(5) with a Prandtl number fixed at 0.7. In the study, the vertical distance between the inner cylinders was changed by 0.1L within a range of 0.1-0.4L. As a result, the steady state represents regardless of the cylinder's vertical location at Ra=10(4), while the unsteady characteristic represents based on the location of the cylinders at Ra=10(5). When the distance between cylinders is close and the space between the upper cylinder and the channel wall is large enough, the interaction between the cylinders causes an unsteady three-dimensional flow compared to the steady flow. When the distance between cylinders and the Rayleigh number are increased, the surface averaged Nusselt number of cylinders also increases.