Oscillations of Large-Scale Structures in turbulent Mixed Convection in a rectangular enclosure

Abstract

The term mixed convection is used to describe the process of heat transfer in fluids where forced convection and thermal convection coexist. Mixed convection is an often occurring flow condition e.g. in the oceans, atmosphere, indoor climatisation or industrial processes and applications. In many flow situations convection is the prevalent transport mechanism of heat whereas the heat transfer strongly depends on the dynamics of the largescale structures. In this study we investigate the formation of large-scale circulation (LSC) in mixed convection and the influence of the dynamics of the LSC, also known as mean wind, on the heat transfer. Measurements of the heat transfer in mixed convection revealed very low frequency oscillations in the heat transfer, which strongly depend on the magnitude of the Reynolds number and Rayleigh number as well as on the Archimdes number.