This study applies the lattice Boltzmann method (LBM) to simulate incompressible steady low Reynolds number backward-facing step flows. In order to restrict the simulations to two-dimensional flows, the investigated Reynolds number range is limited to a maximum value of Re=200. The field synergy principle is applied to demonstrate that the increased interruption within the fluid caused by the introduction of two inclined plates reduces the intersection angle between the velocity vector and the temperature gradient. The present results obtained for the velocity and temperature fields are found to be in good agreement with the published experimental and numerical results. Furthermore, the numerical results confirm the relationship between the velocity and temperature gradient predicted by the field synergy principle.