Ablation of sloping ice faces into polar seawater

• Published in: Journal of Fluid Mechanics
• Main Authors: Mondal, Mainak, Gayen, Bishakhdatta, Griffiths, Ross, Kerr, Ross
• Format: Article in Journal/Newspaper
• Language: English
• Published: Cambridge University Press
• Subjects: buoyant boundary layers; ice sheets; turbulent convection; Antarctic; Antarctic Ocean; Antarc*; Australian Antarctic Division
• Online Access: http://hdl.handle.net/1885/196871; https://doi.org/10.1017/jfm.2018.970; https://openresearch-repository.anu.edu.au/bitstream/1885/196871/6/ablation_sloping_iceface_mainak.pdf.jpg

The effects of the slope of an ice–seawater interface on the mechanisms and rate of ablation of the ice by natural convection are examined using turbulence-resolving simulations. Solutions are obtained for ice slopes ???? , at a fixed ambient salinity and temperature, chosen to represent common Antarctic ocean conditions. For laminar boundary layers the ablation rate decreases with height, whereas in the turbulent regime the ablation rate is found to be height independent. The simulated laminar ablation rates scale with ???? , whereas in the turbulent regime it follows a ???? scaling, both consistent with the theoretical predictions developed here. The reduction in the ablation rate with shallower slopes arises as a result of the development of stable density stratification beneath the ice face, which reduces turbulent buoyancy fluxes to the ice. The turbulent kinetic energy budget of the flow shows that, for very steep slopes, both buoyancy and shear production are drivers of turbulence, whereas for shallower slopes shear production becomes the dominant mechanism for sustaining turbulence in the convective boundary layer. Computations were carried out using the Australian National Computational Infrastructure, through the National Computational Merit Allocation Scheme supported Ablation of a sloping ice face 569 by the Australian Government. This work was supported by Australian Research Council grants DP120102772 and DP120102744. B.G. was supported by ARC DECRA Fellowship DE140100089 and an Australian Antarctic Division RJL Hawk Fellowship to B.G.