title: Non-oberbeck-boussinesq effects in gaseous Rayleigh-Bénard convection.
abstract: Non-Oberbeck-Boussinesq (NOB) effects are measured experimentally and calculated theoretically for strongly turbulent Rayleigh-Bénard convection of ethane gas under pressure where the material properties strongly depend on the temperature. Relative to the Oberbeck-Boussinesq case we find a decrease of the central temperature as compared to the arithmetic mean of the top- and bottom-plate temperature and an increase of the Nusselt number. Both effects are of opposite sign and greater magnitude than those for NOB convection in liquids like water.
authors.affiliation: Department of Physics and iQCD, University of California, Santa Barbara, California 93106, USA.
authors.forename: Guenter
authors.initials: G
authors.lastname: Ahlers
authors.forename: Francisco Fontenele
authors.initials: FF
authors.lastname: Araujo
authors.forename: Denis
authors.initials: D
authors.lastname: Funfschilling
authors.forename: Siegfried
authors.initials: S
authors.lastname: Grossmann
authors.forename: Detlef
authors.initials: D
authors.lastname: Lohse