Effects of rectangular, semi-circular and triangular cross-section blocks on natural convection in vertical channel

Considering widespread applications of natural convection, determination of natural convection heat transfer charactaristics of surfaces is found essential. In this study, fluid motion and heat transfer occured due to natural convection in vertical channel with both walls heated is investigated numerically. Properties of air is used in calcularions. Solutions are performed for two dimensional and laminar flow with Boussinesq approximation. Wall temperature is considered constant. Blocks with different geometries are placed in facing one another and staggered manner and it is aimed to bring the heat flux from surface higher than that of unblocked channel. Effects of aspect ratio of channel on mean heat flux from channel wall and mean Nusselt number of channel wall are also studied. Block geometry?s effects on local Nusselt number are presented by means of diagrams. It is determined that, vortex fields occured beyond blocks were minimum for semi-circular blocks where they are maximum for rectangular blocks. Further investigations demonstrated that, vortex fields become smaller for all three block cross-sections when blocks are staggered. As a result, heat flux from semi-circular blocked channel wall with respect to walls with other two geometries and for each block geometry heat transfer from channel walls with staggered placed blocks with respect to walls with straight placed blocks is calculated higher. Eventually it is found that, mean heat flux increases with increasing aspect ratio of channel.