Numerical simulations have been undertaken for the problem of natural convection flow in a square cavity. The finite element method is applied to governing equations of laminar flow in a series of Rayleigh numbers from up to . To increase the performance of square cavities, the hot and cold walls have been tilted from the vertical position. The solutions of the base cavity and tilting-wall cavity problem have been performed; flow and thermal field solutions have been presented for a few numbers of cases. Increasing density uniform grids with respect to Rayleigh numbers have been served in all cases, and a grid study has been performed to guarantee accurate solutions. The tilting angles have been chosen as 3 or 5 deg, and the direction of rotation was inside or outside. In some cases, the heat transfer performance of the cavity has been corrupted; however, an increase in the performance of up to 7% was acquired.