TY - JOUR
T1 - Ablation of sloping ice faces into polar seawater
AU - Mondal, Mainak
AU - Gayen, Bishakhdatta
AU - Griffiths, Ross W.
AU - Kerr, Ross C.
N1 - Publisher Copyright:
© 2019 Cambridge University Press.
PY - 2019/3/25
Y1 - 2019/3/25
N2 - 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 θ = 2°-90°, 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 (sinθ)1/4, whereas in the turbulent regime it follows a (sin θ)2/3 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.
AB - 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 θ = 2°-90°, 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 (sinθ)1/4, whereas in the turbulent regime it follows a (sin θ)2/3 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.
KW - buoyant boundary layers
KW - ice sheets
KW - turbulent convection
UR - http://www.scopus.com/inward/record.url?scp=85060726284&partnerID=8YFLogxK
U2 - 10.1017/jfm.2018.970
DO - 10.1017/jfm.2018.970
M3 - Article
SN - 0022-1120
VL - 863
SP - 545
EP - 571
JO - Journal of Fluid Mechanics
JF - Journal of Fluid Mechanics
ER -