title: Density fluctuations in strongly stratified two-dimensional turbulence.
abstract: We present a study of density fluctuations in two-dimensional soap-film convection. When the temperature difference (DeltaT) imposed vertically along the film is smaller than a critical value (DeltaT(C) approximately 48 K), the convective motion is in a strongly stratified state and the frequency power spectrum of density fluctuations shows a Bolgiano-like scaling f(-7/5) in the buoyancy subrange. When DeltaT>DeltaT(C), the fluid motion crosses over to a strongly mixed state characterized by the emergence of a large-scale circulation. The density power spectrum in this state has a passive-scalar-like scaling f(-1.0).
authors.affiliation: Department of Physics, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
authors.forename: X L
authors.initials: XL
authors.lastname: Wu
authors.forename: Ke-Qing
authors.initials: KQ
authors.lastname: Xia