This study investigates skin-friction drag reduction by large-scale control using buoyancy forces in a fully developed turbulent flow under a constant pressure gradient, using direct numerical simulations. The heating and cooling regions on the channel walls are alternated in the spanwise direction, thereby generating buoyancy variations. As the Richardson number increases, the drag reduction effect is enhanced, resulting in a maximum drag reduction of 5.85% at λ = 2π and Ri = 4 with opposite-phase wall heating and cooling.

Direct numerical simulation, Large-scale control, Skin-friction drag reduction