scholarly journals Numerical Simulation of Solidification of Colloids Inside a Differentially Heated Cavity

2015 ◽  
Vol 137 (7) ◽  
Author(s):  
Yousef M. F. EL Hasadi ◽  
J. M. Khodadadi
Keyword(s):  
Solid Phase ◽  
Colloidal Suspension ◽  
Concentration Field ◽  
Liquid Interface ◽  
Thermosolutal Convection ◽  
Alumina Nanoparticles ◽  
Convection Cell ◽  
Fluid Mixture ◽  
Solid Liquid Interface ◽  
Solid Liquid

Development of the solid–liquid interface, distribution of the particle concentration field, as well as the development of thermosolutal convection during solidification of colloidal suspensions in a differentially heated cavity are investigated. The numerical model is based on the one-fluid mixture approach combined with the single-domain enthalpy porosity model for phase change, and it is implemented in fluent software package. The linear dependence of the liquidus and solidus temperatures with the concentration of the nanoparticles was assumed. A colloidal suspension consisting of water and copper or alumina nanoparticles were considered. In the current investigation, the nanoparticle size selected was 5 and 2 nm. The suspension was solidified unidirectionally inside a square differentially heated cavity that was cooled from the left side. It was found that the solid–liquid interface changed its morphology from a planar shape to a dendritic one as the solidification process proceeds in time, due to the constitutional supercooling that resulted from the increased concentration of particles at the solid–liquid interface rejected from the crystalline phase. Initially, the flow consisted of two vortices rotating in opposite directions. However, at later times, only one counter clockwise rotating cell survived. Changing the material of the particle to alumina resulted in crystallized phase with a higher concentration of particles. If it is compared to that of the solid phase resulted from freezing the copper–water colloidal suspension. Decreasing the segregation coefficient destabilizes the solid–liquid interface and increases the intensity of the convection cell with respect to that of the case of no particle rejection. At slow freezing rates, the resulting crystal phase consisted of lower particle content compared to the case of higher freezing rate.

Numerical Simulation of Solidification of Colloidal Suspensions Inside a Differentially-Heated Cavity

2013 ◽  
Author(s):  
Yousef M. F. El Hasadi ◽  
J. M. Khodadadi
Keyword(s):  
Solid Phase ◽  
Colloidal Suspension ◽  
Concentration Field ◽  
Colloidal Suspensions ◽  
Liquid Interface ◽  
Alumina Nanoparticles ◽  
Convection Cell ◽  
Fluid Mixture ◽  
Solid Liquid Interface ◽  
Solid Liquid

Development of the solid-liquid interface, distribution of the particle concentration field, as well as the development of thermo-solutal convection during solidification of colloidal suspensions in a differentially-heated cavity is investigated. The numerical model is based on the one-fluid-mixture approach combined with the single-domain enthalpy-porosity model for phase change. The linear dependence of the liquidus concentration of the nanoparticles was assumed. A colloidal suspension consisting of water and copper, and alumina nanoparticles were considered. In the current investigation, the nanoparticle size selected was 2 nm. The suspension was solidified unidirectionally inside a square differentially-heated cavity that was cooled from the left side. It was found that the solid-liquid interface changed its morphology from a planar shape to a dendritic one as the solidification process proceeds in time, due to the constitutional supercooling that resulted from the increased concentration of particles at the solid-liquid interface rejected from the crystalline phase. Initially, the flow consisted of two vortices rotating in opposite directions. However, at later times only one counter clockwise rotating cell survived. Changing the material of the particle to alumina results in crystallized phase with a higher concentration of particles if it is compared to that of the solid phase resulted from freezing the copper-water colloidal suspension. Decreasing the segregation coefficient destabilize the solid-liquid interface, and increase the intensity of the convection cell with respect to that of the case of no particle rejection. At slow freezing rates, the crystal phase resulted consisted of lower particle content if it is compared to that resulted from higher freezing rate.

Numerical Simulation of the Effect of the Size of Nanoparticles on the Solidification Process of Nanoparticle-Enhanced Phase Change Materials

2012 ◽  
Author(s):  
Yousef M. F. El Hasadi ◽  
J. M. Khodadadi
Keyword(s):  
Particle Size ◽  
Phase Change ◽  
Phase Change Materials ◽  
Concentration Field ◽  
Solidification Process ◽  
Liquid Interface ◽  
Constitutional Supercooling ◽  
Fluid Mixture ◽  
Solid Liquid Interface ◽  
Solid Liquid

Nanoparticle-enhanced phase change materials (NEPCM) were proposed recently as alternatives to conventional phase change materials due to their enhanced thermophysical properties. In this study, the effect of the size of the nanoparticles on the morphology of the solid-liquid interface and evolving concentration field, during solidification had been reported. The numerical method that was used is based on the one-fluid-mixture model. The model takes into account the thermal as well as the solutal convection effects. A square cavity model was used in the simulation. The NEPCM that was composed of a suspension of copper nanoparticles in water was solidified from the bottom. The nanoparticles size used were 5 nm and 2 nm. The temperature difference between the hot and cold sides was 5 degrees centigrade and the loading of the nanoparticles that have been used in the simulation was 10% by mass. The results obtained from the model were compared with those existing in the literature, and the comparison was satisfactory. The solid-liquid interface for the case of NEPCM with 5 nm particle size was almost planar throughout the solidification process. However, for the case of the NEPCM with particle size of 2 nm, the solid-liquid interface evolved from a planar stable shape to an unstable dendritic shape, as the solidification process proceeded with time. This was attributed to the constitutional supercooling effect. It has been observed that the constitutional supercooling effect is more pronounced as the particle size decreases. Furthermore, the freezing time increases as the particle size decreases.

Crystallization of liquids in the vicinity of a solid

1981 ◽  
Vol 34 (1) ◽  
pp. 1
Author(s):  
JE Lane ◽  
TH Spurling
Keyword(s):  
Monte Carlo ◽  
Monte Carlo Simulations ◽  
Solid Phase ◽  
Adsorbed Layer ◽  
Liquid Interface ◽  
Spherically Symmetric ◽  
Present Evidence ◽  
Ensemble Monte Carlo ◽  
Solid Liquid Interface ◽  
Solid Liquid

We present evidence, gained from grand ensemble Monte Carlo simulations of the solid/liquid interface, that an adsorbed layer of spherically symmetric liquid particles can have a crystal-like structure even if the solid phase is structureless.

Transient Freezing of Liquids in Forced Flow Inside Circular Tubes

1969 ◽  
Vol 91 (3) ◽  
pp. 385-389 ◽  
Author(s):  
M. N. O¨zis¸ik ◽  
J. C. Mulligan
Keyword(s):  
Solid Phase ◽  
Freezing Temperature ◽  
Local Heat ◽  
Liquid Interface ◽  
Forced Flow ◽  
Transfer Rates ◽  
Tube Wall Temperature ◽  
Temperature Constant ◽  
Solid Liquid Interface ◽  
Solid Liquid

The transient freezing of a liquid flowing inside a circular tube is investigated analytically under the assumption of a constant tube wall temperature which is lower than the freezing temperature, constant properties, a slug-flow velocity profile and quasisteady state heat conduction in the solid phase. The variation of the local heat flux and the profile of the solid-liquid interface during freezing has been determined as a function of time and position along the tube. The analysis produced steadystate heat transfer rates and profiles for the solid-liquid interface which agreed well with experiments.

Study on the Natural Convection and Formation of Periodic Diphase Dendrite in Al-La Alloys

2010 ◽  
Vol 129-131 ◽  
pp. 1308-1312
Author(s):  
Ya Hong Zheng ◽  
Yan Lin Wang ◽  
Zi Dong Wang
Keyword(s):  
Crystal Growth ◽  
Natural Convection ◽  
Concentration Distribution ◽  
Concentration Field ◽  
Growth Direction ◽  
Liquid Interface ◽  
Dendrite Morphology ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Interface Edge

In the crystal growth process, the temperature distribution and concentration distribution at the solid-liquid interface edge are always the hot problems. In this paper, we study the concentration distribution at the solid-liquid interface edge under the natural convection conditions, we find that the concentration field is oscillating exponential decline or rose along the crystal growth direction. We also study the dendrite morphology of Al-La alloys using the experimental method, the results show that the microstructure of Al-35%La alloys is different from the common microstructure of hypereutectic alloy during the conventional casting process, the first crystalline phase is Al11La3, which composition is discontinuous along the growth direction, the main dendrite is composed of α-Al alternating with Al11La3, the results of SEM and XRD show that the chemical composition along the main dendrite exhibits periodic behavior, therefore, this microstructure is named as periodic diphase dendrite structure.

Finite Elenent Analysis of The Effect of a Non-Planar Solid-Liquid Interface on The Lateral Solute Segregation During Unidirectional Solidification.

1981 ◽  
Vol 9 ◽  
Author(s):  
F. M. Carlson ◽  
L-Y Chin ◽  
A. L. Fripp ◽  
R. K. Crouch
Keyword(s):  
Finite Element ◽  
Concentration Field ◽  
Solute Segregation ◽  
Planar Interface ◽  
Unidirectional Solidification ◽  
Liquid Interface ◽  
Interface Shape ◽  
Element Technique ◽  
Solid Liquid Interface ◽  
Solid Liquid

ABSTRACTThe effect of solid-liquid interface shape on lateral solute segregation during steady-state unidirectional solidification of a binary mixture is calculated under the assumption of no convection in the liquid. A finite element technique is employed to compute the concentration field in the liquid and the lateral segregation in the solid with a curved boundary between the liquid and solid phases. The computational model is constructed assuming knowledge of the solid-liquid interface shape; no attempt is made to relate this shape to the thermal field. The influence of interface curvature on the lateral compositional variation is investigated over a range of system parameters including diffusivity, growth speed, distribution coefficient, and geometric factors of the system. In the limiting case of a slightly non-planar interface, numerical results from the finite element technique are in good agreement with the analytical solutions of Coriell and Sekerka obtained by using linear theory. For the general case of highly non-planar interface shapes, the linear theory fails and the concentration field in the liquid as well as the lateral solute segregation in the solid can be calculated by using the finite element method.

scholarly journals The combined effects of shear and buoyancy on phase boundary stability

2019 ◽  
Vol 868 ◽  
pp. 648-665 ◽  
Author(s):  
S. Toppaladoddi ◽  
J. S. Wettlaufer
Keyword(s):  
Shear Flow ◽  
Solid Phase ◽  
Liquid Interface ◽  
Flow Instabilities ◽  
Flow Strength ◽  
Buoyancy Driven Flows ◽  
The Stability ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
Boundary Stability

We study the effects of externally imposed shear and buoyancy driven flows on the stability of a solid–liquid interface. A linear stability analysis of shear and buoyancy-driven flow of a melt over its solid phase shows that buoyancy is the only destabilizing factor and that the regime of shear flow here, by inhibiting vertical motions and hence the upward heat flux, stabilizes the system. It is also shown that all perturbations to the solid–liquid interface decay at a very modest shear flow strength. However, at much larger shear-flow strength, where flow instabilities coupled with buoyancy might enhance vertical motions, a re-entrant instability may arise.

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