An investigation of natural convection in parallel square plates with a heated top surface by a hybrid boundary condition

Natural convection in parallel squares plats with a heated top surface is investigated numerically. For solving a problem induced by different directions between the thermal diffusion and main flow streams, a hybrid boundary condition composed of the absorbing boundary condition and local one-dimensional inviscid relations (LODI) method is then adopted in artificial buffer zones. Methods of the Roe scheme, preconditioning and dual time stepping matching the Monotone Upstream-centered Schemes for Conservation Laws (MUSCL) are used to solve low speed compressible flows caused by natural convection. The results show that the hybrid boundary condition successfully prevents the rebound of heat energy from the artificial buffer zone back to the domain. The area-averaged Nusselt numbers of this study are slightly larger than those of existing experimental results, and the averaged deviation is about 10%.