Fully developed anelastic convection with no-slip boundaries

• Published in: Journal of fluid mechanics Vol. 930
• Main Authors: Jones, Chris A., Mizerski, Krzysztof A., Kessar, Mouloud
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 10.01.2022; Cambridge University Press (CUP)
• Subjects: Anelasticity; Approximation; Boundaries; Boundary conditions; Boundary layers; Boussinesq approximation; Boussinesq equations; Convection; Density; Entropy; Experiments; Fluid flow; Heat; Heat transport; JFM Papers; Physics; Prandtl number; Rayleigh number; Reynolds number; Scaling; Scaling laws; Simulation; Slip; Temperature; Temperature ratio; Thin films; Viscosity; boundary layer structure; stratified turbulence; Bénard convection
• ISSN: 0022-1120; 1469-7645
• DOI: 10.1017/jfm.2021.905

Anelastic convection at high Rayleigh number in a plane parallel layer with no slip boundaries is considered. Energy and entropy balance equations are derived, and they are used to develop scaling laws for the heat transport and the Reynolds number. The appearance of an entropy structure consisting of a well-mixed uniform interior, bounded by thin layers with entropy jumps across them, makes it possible to derive explicit forms for these scaling laws. These are given in terms of the Rayleigh number, the Prandtl number and the bottom to top temperature ratio, which also measures how much the density varies across the layer. The top and bottom boundary layers are examined and they are found to be very different, unlike in the Boussinesq case. Elucidating the structure of these boundary layers plays a crucial part in determining the scaling laws. Physical arguments governing these boundary layers are presented, concentrating on the case in which the boundary layers are so thin that temperature and density vary little across them, even though there may be substantial temperature and density variations across the whole layer. Different scaling laws are found, depending on whether the viscous dissipation is primarily in the boundary layers or in the bulk. The cases of both high and low Prandtl number are considered. Numerical simulations of no-slip anelastic convection up to a Rayleigh number of $10^7$ have been performed and our theoretical predictions are compared with the numerical results.