An experimental and numerical investigation into the sensitivity of Rayleigh-Bénard convection to heat loss through the sidewalls

Thermal buoyancy flows and related heat transfer problems play a crucial role in a variety of fields and industrial applications. The present study is structured around the main objective of systematically investigating the response of fluid convection of the Rayleigh–Bénard type to heat loss taking place through the lateral walls of the considered fluid container. We elucidate, both experimentally and numerically, new aspects which deeply affect the dynamics when the classical assumptions of adiabatic or conducting walls cease to be valid. The emerging spatio-temporal behaviors are examined with respect to several parameters or conditions, including the dimensionality of the system (made accessible by dedicated numerical simulations based on the time-dependent and non-linear governing equations), the average temperature of the liquid, the applied temperature difference, the dependence of fluid properties on temperature and the intensity of heat transfer to the ambient. The results reveal the interesting triadic relationship among the heat exchanged through non-thermally controlled walls, the hierarchy of bifurcations displayed by the flow and the related multiplicity of solutions.