Wall Effects in Turbulent Rayleigh-Benard Convection in a Long Rectangular Cell

Abstract

Direct numerical simulations of turbulent Rayleigh-B´enard convection have been carried out in a rectangular geometry with two different configurations employing either solid walls or periodic boundaries in longitudinal direction. The results show that the infinitely long rectangular cell delays the onset of convection, and hence the transition to a three-dimensional flow field. The analysis of energy spectra at various wall distances indicates that thermal energy held by small scale fluctuation in the vicinity of the wall is transferred into the large scales of the velocity field as wall distance increases.