Experimental study of the velocity field in Rayleigh-Bénard convection

Abstract

Local velocity measurements performed in a convecting layer of fluid show that the velocity field can be described by a dominant fundamental velocity mode mixed with an increasing proportion of second and third harmonics as ε, the reduced distance to the convective threshold R c , is increased from 0 to ∼ 10. The spatial and thermal dependences of the amplitudes of these different modes are reported and compared with theoretical predictions.