Flux scaling and plume structure in high Ra - high Sc turbulent convection

Abstract

The arrangement of brine above water across a micro porous permeable membrane is used to study high Rayleigh Number($10^{11}- 10^{10}$) high Schmidt number(650)turbulent convection. The flux shows 4/3$^{rd}$ scaling with line plume as the near wall coherent structures. Shifting of multiple large scale flow cells result in changing near membrane mean shear directions for large aspect ratios. Lower aspect ratios show single large scale flow cell and constant sense of mean shear.Comment: 7 pages, 7 Figures, Published in Proceedings of the Tenth Asian Congress of Fluid Mechanics 17--21, May 2004, Peradeniya, Srilank