The growth of compositionally stratified solid above a horizontal boundary

1989 ◽  
Vol 199 ◽  
pp. 29-53 ◽  
Author(s):  
Andrew W. Woods ◽  
Herbert E. Huppert
Keyword(s):  
Laboratory Experiments ◽  
Thermal Flux ◽  
Far Field ◽  
Diffusive Transport ◽  
Heavy Fluid ◽  
Heavy Component ◽  
Simple Theoretical Model ◽  
Fixed Composition ◽  
Composite Solid ◽  
Compositional Convection

The compositional stratification in solid formed by cooling a binary alloy from below is investigated theoretically and experimentally. It is shown that in order to grow composite solid the boundary temperature needs to be below the eutetic temperature. Two separate cases are considered. In the first, heavy fluid is released on solidification. The solid growth is then governed by the diffusive transport of heat and composition. The resultant solid is shown to have a fixed composition until the far-field conditions change. In the second case, light fluid is released on solidification. This generates turbulent compositional convection in the melt which significantly increases the transport of heat and composition across the solid/melt interface. As a result, the fraction of heavy component in the solid initially increases, but subsequently decreases to conserve mass. A simple theoretical model, using the approximation of a flat solid/melt interface is developed; this predicts differences in the thermal flux in saturated and undersaturated melts. Laboratory experiments involving aqueous solutions of sodium carbonate cooled from below which released light fluid displayed compositional convection and stratification of the solid as predicted.

scholarly journals Inclusion of landslide tsunamis generation into a depth integrated wave model

2010 ◽  
Vol 10 (11) ◽  
pp. 2259-2268 ◽  
Author(s):  
C. Cecioni ◽  
G. Bellotti
Keyword(s):  
Field Equation ◽  
Small Amplitude ◽  
Laboratory Experiments ◽  
Three Dimensional ◽  
Wave Model ◽  
Dispersive Equations ◽  
Far Field ◽  
Mild Slope Equation ◽  
Calculation Results ◽  
Propagation Of Waves

Abstract. A numerical model based on the mild slope equation, suitable to reproduce the propagation of small amplitude tsunamis in the far field, is extended to reproduce the generation and the propagation of waves generated by landslides. The wave generation is modeled through a forcing term included in the field equation, which reproduces the effects of the movement of a submerged landslide on the fluid. The measurements of three dimensional laboratory experiments, which simulate tsunamis generated by landslide sliding along the flank of a conical island, are compared with the theoretical calculation results. The present approach is also compared with the similar method of Tinti et al. (2006) used for the generation of these waves in depth integrated model, and the different behavior when using frequency-dispersive and non-dispersive equations is highlighted.

Plasma Jet Ignition of Methanol at Sub-Zero Temperatures

1994 ◽  
Vol 208 (3) ◽  
pp. 153-159 ◽  
Author(s):  
J R Dawe ◽  
P R Smy ◽  
R F Haley ◽  
J D Dale ◽  
M F Bardon ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Laboratory Experiments ◽  
Plane Surface ◽  
Plasma Jet ◽  
Pulsed Plasma ◽  
Test Liquid ◽  
Cold Starting ◽  
Simple Theoretical Model ◽  
Sufficient Energy ◽  
Fuel Vaporization

Use of a pulsed plasma jet igniter to improve low-temperature starting of 100 per cent methanol (M100) fuelled engines is explored. A simple theoretical model of heat transfer from plasma to liquid methanol shows that sufficient energy is transferred for fuel vaporization in cold starting. Two laboratory experiments test liquid plane surface and droplet modes of ignition. An ordinary four cylinder auto engine fitted with plasma jet igniters is tested for cold starting in a Canadian winter, and cold starting is improved from +10°C (conventional ignition) to −16°C.

The thermal bar

1992 ◽  
Vol 236 ◽  
pp. 27-42 ◽  
Author(s):  
S. S. Zilitinkevich ◽  
K. D. Kreiman ◽  
A. Yu. Terzhevik
Keyword(s):  
Laboratory Experiments ◽  
Heat Budget ◽  
Traditional Approach ◽  
Laminar Regime ◽  
Laboratory Measurements ◽  
Cold Zone ◽  
Thermal Bar ◽  
Simple Theoretical Model ◽  
Theoretical Predictions ◽  
Zone Ii

A simple theoretical model of the thermal bar is derived on the basis of heat budget equations for the following three zones of a wedge-shaped water basin warmed from above: (i) stably stratified shallow warm-water zone; (ii) vicinity of the bar; (iii) convectively mixed deep cold zone. In contrast to the traditional approach, advective warming of the vicinity of the bar and associated facilitating of the thermal bar propagation are taken into account. Theoretical predictions are compared with the data of lacustrine and laboratory measurements taken from current literature. New laboratory experiments have been carried out to examine the laminar regime of the thermal bar.

scholarly journals Orientation Fabrics in Lake Ice

1962 ◽  
Vol 4 (33) ◽  
pp. 367-370 ◽  
Author(s):  
J. B. Lyons ◽  
R. E. Stoiber
Keyword(s):  
Crystal Growth ◽  
Laboratory Experiments ◽  
Thermal Flux ◽  
Thick Layer ◽  
Supercooled Water ◽  
Field Observations ◽  
Lake Ice ◽  
Geometric Factors ◽  
Mechanical Fragmentation ◽  
Crystallographic Orientations

AbstractLaboratory experiments and field observations permit an explanation of the varying crystallographic orientations observed in lake ice in terms of four factors: (1) coincidence of the plane of most rapid growth in ice (the basal plane) with the vector of thermal flux, (2) mechanical fragmentation of early-formed dendrites and plates by winds above a critical velocity (approximately 2.7 m./sec.), (3) the presence of a sufficiently thick layer of supercooled water to permit vertical crystal growth, and (4) the operation of geometric factors, first pointed out by Perey and Pounder, which result in the gradual elimination of the flatter plates of growing ice by the steeper ones.

scholarly journals Impact of Thermally Driven Turbulence on the Bottom Melting of Ice

2016 ◽  
Vol 46 (4) ◽  
pp. 1171-1187 ◽  
Author(s):  
T. Keitzl ◽  
J. P. Mellado ◽  
D. Notz
Keyword(s):  
Laboratory Experiments ◽  
Scaling Laws ◽  
Rate Increase ◽  
Strong Temperature Dependence ◽  
Far Field ◽  
Field Temperature ◽  
Thermally Driven ◽  
Flow Features ◽  
Ice Water ◽  
Diffusive Layer

AbstractDirect numerical simulation and laboratory experiments are used to investigate turbulent convection beneath a horizontal ice–water interface. Scaling laws are derived that quantify the dependence of the melt rate of the ice on the far-field temperature of the water under purely thermally driven conditions. The scaling laws, the simulations, and the laboratory experiments consistently yield that the melt rate increases by two orders of magnitude, from ⋍101 to ⋍103 mm day−1, as the far-field temperature increases from 4° to 8°C. The strong temperature dependence of the melt rate is explained by analyzing the vertical structure of the flow: For far-field temperatures below 8°C, the flow features a stably stratified, diffusive layer next to the ice that shields it from the warmer, turbulent outer layer. The stratification in the diffusive layer diminishes as the far-field temperature increases and vanishes for far-field temperatures far above 8°C. Possible implications of these results for ice–ocean interfaces are discussed. The drastic melt-rate increase implies that turbulence needs to be considered in the analysis of ice–water interfaces even in shear-free conditions.

Structure of a Convecting Mushy Layer

1990 ◽  
Vol 43 (5S) ◽  
pp. S59-S62 ◽  
Author(s):  
M. Grae Worster
Keyword(s):  
Rayleigh Number ◽  
Laboratory Experiments ◽  
Single Parameter ◽  
Mushy Layer ◽  
Number Density ◽  
Large Solutions ◽  
Model Solutions ◽  
Compositional Convection

Steady, compositional convection in a mushy layer, cooled from below, is analysed for cases in which the Rayleigh number is very large. Solutions are found in which the flow is downwards everywhere except through narrow, vertical chimneys in the layer. The fluxes of mass, heat and solute from the mushy layer into the overlying melt are determined in terms of a single parameter that is proportional to the number density of chimneys. The model solutions can be used to interpret the results of laboratory experiments.

scholarly journals Orientation Fabrics in Lake Ice

1962 ◽  
Vol 4 (33) ◽  
pp. 367-370 ◽  
Author(s):  
J. B. Lyons ◽  
R. E. Stoiber
Keyword(s):  
Crystal Growth ◽  
Laboratory Experiments ◽  
Thermal Flux ◽  
Thick Layer ◽  
Supercooled Water ◽  
Field Observations ◽  
Lake Ice ◽  
Geometric Factors ◽  
Mechanical Fragmentation ◽  
Crystallographic Orientations

AbstractLaboratory experiments and field observations permit an explanation of the varying crystallographic orientations observed in lake ice in terms of four factors: (1) coincidence of the plane of most rapid growth in ice (the basal plane) with the vector of thermal flux, (2) mechanical fragmentation of early-formed dendrites and plates by winds above a critical velocity (approximately 2.7 m./sec.), (3) the presence of a sufficiently thick layer of supercooled water to permit vertical crystal growth, and (4) the operation of geometric factors, first pointed out by Perey and Pounder, which result in the gradual elimination of the flatter plates of growing ice by the steeper ones.

Modelling Rayleigh–Taylor instability of a sedimenting suspension of several thousand circular particles in a direct numerical simulation

2001 ◽  
Vol 434 ◽  
pp. 23-37 ◽  
Author(s):  
T. W. PAN ◽  
D. D. JOSEPH ◽  
R. GLOWINSKI
Keyword(s):  
Rectangular Domain ◽  
Two Dimensions ◽  
Taylor Instability ◽  
Heavy Fluid ◽  
Viscous Potential Flow ◽  
Rayleigh Taylor Instability ◽  
Solid Liquid ◽  
The Waves ◽  
Solid Walls ◽  
Composite Solid

In this paper we study the sedimentation of several thousand circular particles in two dimensions using the method of distributed Lagrange multipliers for solid–liquid flow. The simulation gives rise to fingering which resembles Rayleigh–Taylor instabilities. The waves have a well-defined wavelength and growth rate which can be modelled as a conventional Rayleigh–Taylor instability of heavy fluid above light. The heavy fluid is modelled as a composite solid–liquid fluid with an effective composite density and viscosity. Surface tension cannot enter this problem and the characteristic shortwave instability is regularized by the viscosity of the solid–liquid dispersion. The dynamics of the Rayleigh–Taylor instability are studied using viscous potential flow, generalizing work of Joseph, Belanger & Beavers (1999) to a rectangular domain bounded by solid walls; an exact solution is obtained.

Melting driven by vigorous compositional convection

1994 ◽  
Vol 280 ◽  
pp. 255-285 ◽  
Author(s):  
Ross C. Kerr
Keyword(s):  
Aqueous Solutions ◽  
Continental Crust ◽  
Laboratory Experiments ◽  
Basaltic Magma ◽  
Melting Rate ◽  
Theoretical Expression ◽  
Scaling Analysis ◽  
Thermal Buoyancy ◽  
Geological Situation ◽  
Compositional Convection

The melting of a solid in contact with a hot fluid is quantified for the case in which a difference between the densities of the fluid and of the melted solid is able to drive vigorous compositional convection. A scaling analysis is first used to obtain a theoretical expression for the melting rate that is valid for a certain range of Stefan numbers. This expression is then compared with melting velocities measured in laboratory experiments in which ice and wax are melted when they are overlain or underlain by hot aqueous solutions. The melting velocities are consistent with the theoretical expression, and are found to depend on the heats of solution that are released when the melted solids mix with the solutions. The experiments also indicate that, for vigorous convection to occur during the melting of a floor, the unstable compositional buoyancy needs to be at least twice the stabilizing thermal buoyancy.An important geological situation in which melting occurs is when large volumes of basaltic magma are intruded into the Earth's continental crust. The theoretical and experimental results are used and extended to examine quantitatively the melting of the floor and walls of the magma chamber, and of crustal blocks that fall into the chamber.

scholarly journals Diffusion-controlled dissolution of a binary solid into a ternary liquid with partially molten zone formation

2008 ◽  
Vol 464 (2094) ◽  
pp. 1615-1637 ◽  
Author(s):  
D.C Hatton ◽  
A.W Woods
Keyword(s):  
Molten Zone ◽  
Far Field ◽  
Diffusive Transport ◽  
Zone Formation ◽  
Movement Rates ◽  
Solid Mixture ◽  
Diffusion Controlled ◽  
Nacl Concentration ◽  
Sharp Fronts ◽  
Unique Surface

We build a theoretical model of equilibrium dissolution of a homogeneous, solid mixture of two salts A and B, KCl and NaCl being used as the type example, into an aqueous solution of the two salts, with diffusive transport. We find that there are two sharp dissolution fronts, separating fluid, a partially molten zone containing a single solid and mixed solid. The phase change happens almost entirely at the two sharp fronts. In equilibrium, the leading front exhibits a small amount of precipitation of NaCl, simultaneous with complete dissolution of KCl. There is a unique surface in the space of far-field fluid KCl concentration, far-field fluid NaCl concentration and solid composition, dividing conditions where NaCl is the solid in the partially molten zone, from conditions where KCl is the solid in the partially molten zone. The movement rates of the dissolution fronts decrease as the concentration of either salt in the far-field fluid is increased. The movement rates of the dissolution fronts increase as either far-field temperature is increased, but this effect is smaller than that of concentration. In most circumstances, the dissolution front for a given salt moves more slowly, the more of that salt is present in the original solid, although the mass dissolution rate is not greatly affected by the solid composition.

Sign in / Sign up

Export Citation Format

Share Document