Spatio Temporal Intermittency in Rayleigh-Benard Convection in an Annulus

Abstract

Spatio temporal intermittency is a problem of great current interest that has been theoretically studied in system of coupled maps [Kaneko; Chate’-Manneville], partial differential equations[Chate’-Manneville;Nicolaenko] and in some cellular automata [Chate’-Ma.nneville; Bagnoli et al.; Livi]. It consists of a fluctuating mixture of laminar and turbulent domains with well defined boundaries. Such a behaviour appears also in Rayleigh Berard convection[Ciliberto-Bigazzi; Berge’] and in boundary layer flows[Van Dyke; Tritton]. We report here a statistical analysis of the onset of spatiotemporal intermittency clone in an experiment of Rayleigh-Benard convection. Our results display features typical of phase transitions similar to those obtained by Chate’-Manneville and Kaneko. In what is following we describe very briefly the experimental apparatus. In section 3) we will show the spatial patterns that preceed the spatiotemporal intermittency. In section 4) we descibe the reduction of the space time evolution to a symbolic dynamic and we report only the main results of the statistical analysis whose details have been the object of a previous paper[Ciliberto-Bigazzi].