Influence of local time-periodic heat forcing on the large-scale convective circulation in a square Rayleigh-Bénard cell

Abstract The two-dimensional large-scale circulation in a square Rayleigh-Bénard cell with constant heat flux at the horizontal boundaries and localized time-periodic heating at the vertical boundary is studied. The main focus is on the role of period of forcing, its location and intensity. Even weak forcing of of the total heating power breaks the symmetry and leads to the preferable direction of circulation and appearance of non-symmetric mean flow. The dynamics of the large-scale flow is analyzed using Fourier decomposition. The changes in location of the forcing affect only quantitative flow characteristics, maintaining its structure. The periodic forcing with periods comparable with turnover time does not lead to regular oscillations of the dominant mode. It is shown that the local forcing results in substantial energy variation of the main Fourier modes. The strongest impact on the large-scale circulation characteristics and dynamics is provided by the forcing near the top boundary.