Thermal stratification induced by heating in a non-adiabatic context

Thermal stratification associated with thermal plumes in semi-confined and confined non-adiabatic environments has been investigated using heating experiments performed in the atmosphere of an underground quarry. A 100 W source is used during 24 h, followed by 6 days of recovery. Vertical and horizontal profiles of temperature are recorded in the atmosphere, supplemented by a vertical profile at the wall. During a heating, an equilibrium stratification is observed in the atmosphere, compatible with a filling box mechanism modified by heat exchanges with the boundaries. At the wall, an initial cooling is observed, indicating the importance of phase changes of water in the energy budget. Such experiments should improve our understanding of the effect of turbulent plumes in air, which is relevant for proper ventilation and heating of buildings, and more generally, engineering, cultural and environmental applications.