A Boundary Value Model for an Evaporating Meniscus

2010 ◽  
Author(s):  
Arya Chatterjee ◽  
Joel L. Plawsky ◽  
Peter C. Wayner
Keyword(s):  
Heat Transfer ◽  
Boundary Conditions ◽  
Contact Line ◽  
Effective Means ◽  
Line Region ◽  
Hydrodynamic Slip ◽  
Interface Curvature ◽  
Solid Liquid Interface ◽  
Value Model ◽  
Solid Liquid

The constrained vapor bubble (CVB) experiment is an experiment to study the effect of low Bond numbers on the microscopic and macroscopic transport in a heat pipe. The microscopic (∼30 μm) contact line region, where the solid, liquid and vapor phase meet, is of fundamental importance in this study of fluid flow and heat transfer. This region, while dominated by interfacial forces, is controlled by the boundary conditions set by physics at the macroscopic scale (∼1 mm) on one side and the microscopic scale (∼ 0.1 μm) on the other. Recent experimental investigation by our group has shown that an effective means of changing the microscopic boundary conditions (the wettability of the fluid) is by introducing surface roughness at the nanoscale to the solid surface. Here we attempt to examine some of the experimental results in the light of a model. The model solves a nonlinear, fourth order evolution equation for the film thickness. It also provides the contact angle, interface curvature and heat transfer profile in the contact line region. The model agrees well with the experimental data. The presence of hydrodynamic slip at the solid liquid interface seems to improve the agreement.

scholarly journals Solid–Liquid Interface Temperature Measurement of Evaporating Droplet Using Thermoresponsive Polymer Aqueous Solution

2021 ◽  
Vol 11 (8) ◽  
pp. 3379
Author(s):  
Hyung Ju Lee ◽  
Chan Ho Jeong ◽  
Dae Yun Kim ◽  
Chang Kyoung Choi ◽  
Seong Hyuk Lee
Keyword(s):  
Refractive Index ◽  
Heated Surface ◽  
Liquid Interface ◽  
Interface Temperature ◽  
Thermoresponsive Polymer ◽  
Temperature Deviation ◽  
Line Region ◽  
Optical And Mechanical Properties ◽  
Solid Liquid Interface ◽  
Solid Liquid

The present study aims to measure the solid–liquid interface temperature of an evaporating droplet on a heated surface using a thermoresponsive polymer. Poly(N-isopropylacrylamide) (pNIPAM) was used owing to its sensitive optical and mechanical properties to the temperature. We also measured the refractive index variation of the pNIPAM solution by using the surface plasmon resonance imaging (SPRi). In particular, the present study proposed a new method to measure the solid–liquid interface temperature using the correlation among reflectance, refractive index, and temperature. It was found that the reflectance of a pNIPAM solution decreased after the droplet deposition. The solid–liquid interface temperature, estimated from the reflectance, showed a lower value at the center of the droplet, and it gradually increased along the radial direction. The lowest temperature at the contact line region is present because of the maximum evaporative cooling. Moreover, the solid–liquid interface temperature deviation increased with the surface temperature, which means solid–liquid interface temperature should be considered at high temperature to predict the evaporation flux of the droplet accurately.

Two-Dimensional Transient Heat Transfer Model for High-Temperature Laser-Scanning Confocal Microscopy

2021 ◽  
Author(s):  
Dasith Liyanage ◽  
Suk-Chun Moon ◽  
Ajith S. Jayasekare ◽  
Abheek Basu ◽  
Madeleine Du Toit ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Phase Transformation ◽  
High Temperature ◽  
Laser Scanning ◽  
Laser Scanning Confocal Microscopy ◽  
Transfer Model ◽  
Two Dimensional ◽  
Scanning Confocal Microscopy ◽  
Solid Liquid Interface ◽  
Solid Liquid

Abstract High-temperature laser-scanning confocal microscopy (HT-LSCM) has proven to be an excellent experimental technique through in-situ observations of high temperature phase transformation to study kinetics and morphology using thin disk steel specimens. A 1.0 kW halogen lamp, within the elliptical cavity of the HT-LSCM furnace radiates heat and imposes a non-linear temperature profile across the radius of the steel sample. This local temperature profile when exposed at the solid/liquid interface determines the kinetics of solidification and phase transformation morphology. A two-dimensional numerical heat transfer model for both isothermal and transient conditions is developed for a concentrically solidifying sample. The model can accommodate solid/liquid interface velocity as an input parameter under concentric solidification with cooling rates up to 100 K/min. The model is validated against a commercial finite element analysis software package, Strand7, and optimized with experimental data obtained under near-to equilibrium conditions. The validated model can then be used to define the temperature landscape under transient heat transfer conditions.

Molecular Dynamics Simulations of Interfacial Heat and Mass Transfer at Nanostructured Surface

2007 ◽  
Author(s):  
Gyoko Nagayama ◽  
Masako Kawagoe ◽  
Takaharu Tsuruta
Keyword(s):  
Heat Transfer ◽  
Molecular Dynamics ◽  
Boundary Condition ◽  
Thermal Resistance ◽  
Hydrodynamic Resistance ◽  
Hydrophilic Surface ◽  
Dynamics Simulations ◽  
Solid Liquid Interface ◽  
Solid Liquid ◽  
The Continuum

The nanoscale heat and mass transport phenomena play important roles on the applications of nanotechnologies with great attention to its differences from the continuum mechanics. In this paper, the breakdown of the continuum assumption for nanoscale flows has been verified based on the molecular dynamics simulations and the heat transfer mechanism at the nanostructured solid-liquid interface in the nanochannels is studied from the microscopic point of view. Simple Lennard-Jones (LJ) fluids are simulated for thermal energy transfer in a nanochannel using nonequilibrium molecular dynamics techniques. Multi-layers of platinum atoms are utilized to simulate the solid walls with arranged nanostructures and argon atoms are employed as the LJ fluid. The results show that the interface structure (i.e. the solid-like structure formed by the adsorption layers of liquid molecules) between solid and liquid are affected by the nanostructures. It is found that the hydrodynamic resistance and thermal resistance dependents on the surface wettability and for the nanoscale heat and fluid flows, the interface resistance cannot be neglected but can be reduced by the nanostructures. For the hydrodynamic boundary condition at the solid-liquid interface, the no-slip boundary condition holds good at the super-hydrophilic surface with large hydrodynamic resistance. However, apparent slip is observed at the low hydrodynamic resistance surface when the driving force overcomes the interfacial resistance. For the thermal boundary condition, it is found that the thermal resistance at the interface depends on the interface wettability and the hydrophilic surface has lower thermal resistance than that of the hydrophobic surfaces. The interface thermal resistance decreases at the nanostructed surface and significant heat transfer enhancement has been achieved at the hydrophilic nanostructured surfaces. Although the surface with nanostrutures has larger surface area than the flat surface, the rate of heat flux increase caused by the nanostructures is remarkable.

Use of Scanning Microphotometer to Determine the Evaporative Heat Transfer Characteristics of the Contact Line Region

1981 ◽  
Vol 103 (2) ◽  
pp. 325-330 ◽  
Author(s):  
R. Cook ◽  
C. Y. Tung ◽  
P. C. Wayner
Keyword(s):  
Thin Film ◽  
Heat Transfer ◽  
Heat Flux ◽  
Contact Line ◽  
Heat Transfer Characteristics ◽  
Thin Film Thickness ◽  
Thickness Profile ◽  
Line Region ◽  
Evaporative Heat Transfer

A scanning microphotometer was used to measure in situ the profile of an evaporating decane meniscus in the contact line region on a smooth inclined silicon substrate as a function of the evaporative heat flux. The use of this new experimental design to determine the effect of heat flux on the profile in the contact line region is discussed. The results support the hypothesis that fluid flow in the contact line region of an evaporating thin film results from a change in the thin film thickness profile.

scholarly journals Application of cellular automata and Lattice Boltzmann methods for modelling of additive layer manufacturing

2018 ◽  
Vol 28 (1) ◽  
pp. 31-46 ◽  
Author(s):  
Dmytro Svyetlichnyy ◽  
Michal Krzyzanowski ◽  
Robert Straka ◽  
Lukasz Lach ◽  
W. Mark Rainforth
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Cellular Automata ◽  
Integrated Modelling ◽  
Holistic Model ◽  
Content Type ◽  
Powder Bed ◽  
Physical Mechanisms ◽  
Solid Liquid Interface ◽  
Solid Liquid

Purpose The holistic numerical model based on cellular automata (CA) and lattice Boltzmann method (LBM) are being developed as part of an integrated modelling approach applied to study the interaction of different physical mechanisms in laser-assisted additive layer manufacturing (ALM) of orthopaedic implants. Several physical events occurring in sequence or simultaneously are considered in the holistic model. They include a powder bed deposition, laser energy absorption and heating of the powder bed by the moving laser beam, leading to powder melting or sintering, fluid flow in the melted pool and flow through partly or not melted material, and solidification. The purpose of this study is to develop a structure of the holistic numerical model based on CA and LBM applicable for studying the interaction of the different physical mechanisms in ALM of orthopaedic implants. The model supposed to be compatible with the earlier developed CA-based model for the generation of the powder bed. Design/methodology/approach The mentioned physical events are accompanied by heat transfer in solid and liquid phases including interface heat transfer at the boundaries. The sintering/melting model is being developed using LBM as an independent numerical method for hydrodynamic simulations originated from lattice gas cellular automata. It is going to be coupled with the CA-based model of powder bed generation. Findings The entire laser-assisted ALM process has been analysed and divided on several stages considering the relevant physical phenomena. The entire holistic model consisting of four interrelated submodels has currently been developed to a different extent. The submodels include the CA-based model of powder bed generation, the LBM-CA-based model of heat exchange and transfer, the thermal solid-liquid interface model and the mechanical solid-liquid interface model for continuous liquid flow. Practical implications The results obtained can be used to explain the interaction of the different physical mechanisms in ALM, which is an intensively developing field of advanced manufacturing of metal, non-metal and composite structural parts, for instance, in bio-engineering. The proposed holistic model is considered to be a part of the integrated modelling approach being developed as a numerical tool for investigation of the co-operative relationships between multiphysical phenomena occurring in sequence or simultaneously during heating of the powder bed by the moving high energy heat source, leading to selective powder sintering or melting, fluid flow in the melted pool and through partly (or not) melted material, as well as solidification. The model is compatible with the earlier developed CA-based model for the generation of the powder bed, allowing for decrease in the numerical noise. Originality/value The present results are original and new for the study of the complex relationships between multiphysical phenomena occurring during ALM process based on selective laser sintering or melting, including fluid flow and heat transfer, identified as crucial for obtaining the desirable properties.

Studies on Heat Transfer From a Vertical Cylinder, With or Without Fins, Embedded in a Solid Phase Change Medium

1985 ◽  
Vol 107 (1) ◽  
pp. 44-51 ◽  
Author(s):  
B. Kalhori ◽  
S. Ramadhyani
Keyword(s):  
Heat Transfer ◽  
Experimental Investigation ◽  
Natural Convection ◽  
Solid Phase ◽  
Vertical Cylinder ◽  
Interface Shape ◽  
Fusion Temperature ◽  
Total Heat Transfer ◽  
Solid Liquid Interface ◽  
Solid Liquid

An experimental investigation of melting and cyclic melting and freezing around a vertical cylinder is reported. The studies encompass two cases: a plain vertical cylinder, and a vertical cylinder with fins. In the melting studies, the total heat transfer from the cylinder was measured as a function of time. In addition, measurements have been made of the solid-liquid interface shape after various melting times. In these studies, the solid phase was initially isothermal and either at its fusion temperature or subcooled below the fusion point. The experiments reveal the important influence of natural convection in the liquid phase in both unfinned and finned situations. Subcooling of the solid phase is observed to strongly inhibit heat transfer in the unfinned situation. In the experiment on cyclic melting and freezing, subcooling of the solid phase is once again found to have an important effect on the unfinned situation. Heat transfer from the finned cylinder is much less affected by solid-phase subcooling. All the experiments were performed with 99 percent pure n-eicosane paraffin.

Analytical Solution on the Relation of Technique Parameters for Continuous Casting with Heated Mould

2011 ◽  
Vol 337 ◽  
pp. 225-231
Author(s):  
Feng Ni ◽  
Shi Zhong Wei ◽  
Rui Long
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Coefficient ◽  
Continuous Casting ◽  
Casting Speed ◽  
Specific Conductance ◽  
Liquid Interface ◽  
Mould Temperature ◽  
Interface Position ◽  
Solid Liquid Interface ◽  
Solid Liquid

The technique of continuous casting with heated mould is a kind of near-net-shape processing technology, which combines unidirectional solidification with continuous casting and has been used widely for new material development and processing. A steady-state heat-transfer model was suggested for pure metal case. Some of modeling parameters, such as equivalent specific conductance and equivalent heat-transfer coefficient, etc, had been defined. The analytic solution of temperature profile along the axis of casting rod was obtained for solid-liquid interface to be as origin of position coordinate, by which the relations had been solved among mould temperature, casting speed, solid-liquid interface position, equivalent specific conductance between mould and metal, equivalent heat-transfer coefficient of cooling of cast rod, temperature gradient and cooling rate of melt in front of solid-liquid interface. As an example, the coordinate relations of solid-liquid interface position, mould temperature and casting speed were calculated and compared with experimental results in the case of pure copper. The calculation results conformed very well to the experimental ones. And it was indicated that the cooling rate of melt in front of solid-liquid interface had a nonlinear relation with casting speed during steady continuous casting process.

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