Publications by Andrew Wells


Turbulent plumes from a glacier terminus melting in a stratified ocean

JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS 121 (2016) 4670-4696

SJ Magorrian, AJ Wells


The impact of imperfect heat transfer on the convective instability of a thermal boundary layer in a porous media

JOURNAL OF FLUID MECHANICS 794 (2016) 154-174

J Hitchen, AJ Wells


Solidification of a disk-shaped crystal from a weakly supercooled binary melt.

Physical review. E, Statistical, nonlinear, and soft matter physics 92 (2015) 022406-

DW Rees Jones, AJ Wells

The physics of ice crystal growth from the liquid phase, especially in the presence of salt, has received much less attention than the growth of snow crystals from the vapor phase. The growth of so-called frazil ice by solidification of a supercooled aqueous salt solution is consistent with crystal growth in the basal plane being limited by the diffusive removal of the latent heat of solidification from the solid-liquid interface, while being limited by attachment kinetics in the perpendicular direction. This leads to the formation of approximately disk-shaped crystals with a low aspect ratio of thickness compared to radius, because radial growth is much faster than axial growth. We calculate numerically how fast disk-shaped crystals grow in both pure and binary melts, accounting for the comparatively slow axial growth, the effect of dissolved solute in the fluid phase, and the difference in thermal properties between solid and fluid phases. We identify the main physical mechanisms that control crystal growth and show that the diffusive removal of both the latent heat released and the salt rejected at the growing interface are significant. Our calculations demonstrate that certain previous parametrizations, based on scaling arguments, substantially underestimate crystal growth rates by a factor of order 10-100 for low aspect ratio disks, and we provide a parametrization for use in models of ice crystal growth in environmental settings.


Channelization of plumes beneath ice shelves

JOURNAL OF FLUID MECHANICS 785 (2015) 109-134

MC Dallaston, IJ Hewitt, AJ Wells


Steady turbulent density currents on a slope in a rotating fluid

JOURNAL OF FLUID MECHANICS 746 (2014) 405-436

GE Manucharyan, W Moon, F Sevellec, AJ Wells, J-Q Zhong, JS Wettlaufer


Nonlinear mushy-layer convection with chimneys: stability and optimal solute fluxes

JOURNAL OF FLUID MECHANICS 716 (2013) 203-227

AJ Wells, JS Wettlaufer, SA Orszag


Finite-sample-size effects on convection in mushy layers

JOURNAL OF FLUID MECHANICS 704 (2012) 89-108

J-Q Zhong, AT Fragoso, AJ Wells, JS Wettlaufer


Mushy-layer dynamics in micro and hyper gravity

Physics of Fluids 24 (2012)

JG O'Rourke, AJE Riggs, CA Guertler, PW Miller, CM Padhi, MM Popelka, AJ Wells, AC West, JQ Zhong, JS Wettlaufer

We describe the results of experiments on mushy layers grown from aqueous ammonium chloride solution in normal, micro, and hyper gravity environments. In the fully developed chimney state, the chimney plume dynamics differ strikingly when conditions change from micro to hyper gravity. In microgravity, we find fully arrested plume motion and suppressed convection. As gravity exceeds Earth conditions, we observe a host of phenomena, ranging from arched plumes that undergo forced Rayleigh-Taylor instabilities to in-phase multiple plume oscillatory behavior. For the same initial solute concentrations and fixed boundary cooling temperatures, we find that, in runs of over two hours, the averaged effects of microgravity and hypergravity result in suppressed growth of the mushy layers, a phenomenon caused by a net enhancement of convective heat and solute transport from the liquid to the mushy layers. These behaviors are placed in the context of the theory of convecting mushy layers as studied under normal laboratory conditions. © 2012 American Institute of Physics.


Melting and dissolving of a vertical solid surface with laminar compositional convection

JOURNAL OF FLUID MECHANICS 687 (2011) 118-140

AJ Wells, MG Worster


Brine fluxes from growing sea ice

GEOPHYSICAL RESEARCH LETTERS 38 (2011) ARTN L04501

AJ Wells, JS Wettlaufer, SA Orszag


Maximal Potential Energy Transport: A Variational Principle for Solidification Problems

PHYSICAL REVIEW LETTERS 105 (2010) ARTN 254502

AJ Wells, JS Wettlaufer, SA Orszag


Variations in Ocean Surface Temperature due to Near-Surface Flow: Straining the Cool Skin Layer

JOURNAL OF PHYSICAL OCEANOGRAPHY 39 (2009) 2685-2710

AJ Wells, C Cenedese, JT Farrar, CJ Zappa


A geophysical-scale model of vertical natural convection boundary layers

Journal of Fluid Mechanics 609 (2008) 111-137

AJ Wells, MG Worster

A model is developed for turbulent natural convection in boundary layers formed next to isothermal vertical surfaces. A scaling analysis shows that the flow can be described by plume equations for an outer turbulent region coupled to a resolved near-wall laminar flow. On the laboratory scale, the inner layer is dominated by its own buoyancy and the Nusselt number scales as the one-third power of the Rayleigh number (Nu ∝ Ra z 1/3 ). This gives a constant heat flux, consistent with previous experimental and theoretical studies. On larger geophysical scales the buoyancy is strongest in the outer layer and the laminar layer is driven by the shear imposed on it. The predicted heat transfer correlation then has the Nusselt number proportional to the one-half power of Rayleigh number (Nu ∝ Ra z 1/2 ) so that a larger heat flux is predicted than might be expected from an extrapolation of laboratory-scale results. The criteria for transitions between flow regimes are consistent with a hierarchy of instabilities of the near-wall laminar flow, with a buoyancy-driven instability operating on the laboratory scale and a shear-driven instability operating on geophysical scales. © 2008 Cambridge University Press.