# Convection - Experiments

Turbulent non-Oberbeck Boussinesq convection

For simplicity, most theoretical and numerical studies on convection assume Oberbeck-Boussinesq (OB) conditions, which can be briefly summarized as - Density *ρ*, Isobaric heat capacity *c*_{p}, thermal diffusivity *κ*, viscosity *ν* and isobaric expansion coefficient *α* are independent of temperature *T* and pressure *p*, while only for the buoyancy one assumes a that the density depend linearly on the temperature with coefficient *α*. In many natural and industrial convection systems, however, temperature differences are very large and thus the OB-assumption is violated.

We study Rayleigh-Bénard Convection systems beyond OB approximation using Sulphur Hexafluoride (SF_{6}) near its critical point, where material parameters vary significantly with temperature and pressure. We focus on the two unique characteristics of such system: the deviation of the centre temperature *T*_{c}

from mean temperature *T*_{m} due to the broken symmetry, and its relation to the change in global heat transport efficiency *N**u*/*N**u*_{OB}. There are two goals of the study: 1. to generalized current theories and understandings on the OB system to real-world fluids 2. to eliminate NOB effects in the search of ultimate states.

See also:

Weiss, S., He, X., Ahlers, G., Bodenschatz, E., & Shishkina, O. . Bulk temperature and heat transport in turbulent Rayleigh–Bénard convection of fluids with temperature-dependent properties. Journal of Fluid Mechanics, 851, 374-390 (2018).