Identification of the wind in Rayleigh-Bénard convection

Abstract

Using a symmetry-accounting ensemble-averaging method, we have identified the wind in unbounded Rayleigh-Bénard convection. This makes it possible to distinguish the wind from fluctuations and to identify dynamic features of each. We present some results from processing five independent three-dimensional direct numerical simulations of a Γ=4 aspect-ratio domain with periodic side boundaries at Ra=107 and Pr=1. It is found that the wind boundary layer scales linearly very close to the wall and has a logarithmic region further away. Despite the still noticeable molecular effects, the identification of log scaling and significant velocity and temperature fluctuations well within the thermal boundary layer clearly indicate that the boundary layer cannot be classified as laminar. © 2005 American Institute of Physics.