Journal ArticleDOI
Convection in mushy layers
TLDR
In this paper, the authors present an account of various studies of buoyancy-driven convection in mushy layers, paying particular attention to the complex interactions between solidification and flow that lead to novel styles of convective behavior, including focusing of the flow to produce chimneys.Abstract:
As a molten alloy or any multi-component liquid is cooled and solidified the growing solid phase usually forms a porous matrix through which the residual liquid can flow. The reactive two-phase medium comprising the solid matrix and residual liquid is called a mushy layer. Buoyancy forces, owing primarily to compositional depletion as one or more of the components of the alloy are extracted to form the solid phase, can drive convection in the layer. In this review, I present an account of various studies of buoyancy-driven convection in mushy layers, paying particular attention to the complex interactions between solidification and flow that lead to novel styles of convective behavior, including focusing of the flow to produce chimneys: narrow, vertical channels devoid of solid. I define an ‘ideal’ mushy layer and argue that chimneys are an inevitable consequence of convection in ideal mushy layers. The absence of chimneys in certain laboratory experiments is explained in terms of nonideal effects.read more
Citations
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Journal ArticleDOI
The physics of premelted ice and its geophysical consequences
TL;DR: The physics of the premelting of ice and its relationship with the behavior of other materials more familiar to the condensed-matter community are described in this paper, where a number of the many tendrils of the basic phenomena as they play out on land, in the oceans, and throughout the atmosphere and biosphere are developed.
Journal ArticleDOI
Solidification microstructures: recent developments, future directions
William J. Boettinger,Sam R. Coriell,A.L. Greer,Alain Karma,Wilfried Kurz,Michel Rappaz,Rohit Trivedi +6 more
TL;DR: The status of solidification science is critically evaluated and future directions of research in this technologically important area are proposed in this paper, where the most important advances in solidification sciences and technology of the last decade are discussed: interface dynamics, phase selection, microstructure selection, peritectic growth, convection effects, multicomponent alloys, and numerical techniques.
Journal ArticleDOI
Interfacial conditions between a pure fluid and a porous medium : implications for binary alloy solidification
M. Le Bars,M. Grae Worster +1 more
TL;DR: In this article, the Stokes-Darcy-Brinkman model is applied to some analytically tractable flows through adjacent porous and pure-fluid domains and is compared systematically with the multiple-domain Stokes−Darcy model.
Journal ArticleDOI
Development of a Freckle Predictor via Rayleigh Number Method for Single-Crystal Nickel-Base Superalloy Castings
TL;DR: In this article, a Rayleigh number based criterion is developed for predicting the formation of freckles in Ni-base superalloy castings, which relies on finding the maximum local rayleigh number in the mush, where the ratio of the driving buoyancy force to the retarding frictional force is the largest.
Journal ArticleDOI
Desalination processes of sea ice revisited
TL;DR: In this article, the authors reexamine five processes that have been suggested to be important for the loss of salt from sea ice and show that only gravity drainage and flushing contribute to any measurable net loss.
References
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Journal ArticleDOI
The Growth of Crystals and the Equilibrium Structure of their Surfaces
TL;DR: In this paper, it was shown that the rate of growth of a surface containing dislocations is proportional to the square of the supersaturation for low values and to the first power for high values of the latter.
Journal ArticleDOI
Stability of a Planar Interface During Solidification of a Dilute Binary Alloy
W. W. Mullins,R. F. Sekerka +1 more
TL;DR: In this article, the stability of a moving planar liquid-solid interface during unidirectional freezing of a dilute binary alloy is theoretically investigated by calculating the time dependence of the amplitude of a sinusoidal perturbation of infinitesimal amplitude introduced into the planar shape.
Journal ArticleDOI
Convection of a fluid in a porous medium
TL;DR: In this article, it was shown that under certain conditions convective flow may occur in fluid which permeates a porous stratum and is subject to a vertical temperature gradient, on the assumption that the flow obeys Darcy's law.
Journal ArticleDOI
Convection Currents in a Porous Medium
C. W. Horton,F. T. Rogers +1 more
TL;DR: In this paper, it was shown that the minimum temperature gradient for which convection can occur is approximately 4π2h2μ/kgρ0α D2, where h2 is the thermal diffusivity, g is the acceleration of gravity, μ is the viscosity, k is the permeability, α is the coefficient of cubical expansion, ρ 0 is the density at zero temperature, and D is the thickness of the layer; this exceeds the limiting gradient found by Rayleigh for a simple fluid by a factor of 16D2/27π2