• Journal of the Korean Chemical Society
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• v.15 no.3
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• pp.133-145
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• 1971

A method of theoretical calculation of the thermodynamic properties for liquid-vapor interface of binary solution is developed according to the transient state theory of significant liquid structure. The surface tensions, the adsorbed amounts at the liquid-vapor interface and the activity coefficients of the components for the solutions of $C_6H_{12}-C_6H_6$ $CCI_4-C_6H_6$, $CHCl_3-C_6H_6$, $CHCl_3-CCl_4$, $CCl_4-CS_2$ are calculated through the full ranges of the compositions.

• Transactions of the Korean Society of Mechanical Engineers
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• v.19 no.4
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• pp.1095-1101
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• 1995

Numerical analysis of vertical solidification process allowing solid-liquid density change is performed by a hybrid method between a winite volume method (FVM) and a finite element method (FEM). The investigation focuses on the influence of solid-liquid density change and cooling rates on the motion of solid-liquid interface, solidified mass fraction, temperatures and thermal stresses in the solid region. Due to the density change of pure aluminium, solid-liquid interface moves more slowly but the solidified mass fraction is larger. The cooling rate of the wall is shown to have a significant influence on the phase change heat transfer and thermal stresses, while the density change has a small influence on the motion of the interface, solidified mass fraction, temperature distributions and thermal stresses. As the cooling rate increases, the thermal stresses become higher at the early stage of a solidification process, but it has small influence on the final stresses as the steady state is reached.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.448-450
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• 2010

Free surface liquid jet impingement, which is applicable to cooling of hot plates in a steel-making process, is investigated numerically by solving the conservation equations of mass, momentum and energy in the liquid and gas phases. The free-surface of liquid-gas interface is tracked by an improved level-set method incorporating a sharp-interface technique for accurate imposition of stress and heat flux conditions on the liquid-gas interface. The level-set approach is combined with a non-equilibrium $k-{\omega}$ turbulence model. The computations are made for slit nozzle jets to investigate their flow and cooling characteristics. Also, the effects of jetting angle, velocity and moving velocity of plate on the interfacial motion and the associated flow and temperature fields are quantified.

• Proceedings of the KSME Conference
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• 2000.04b
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• pp.37-44
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• 2000

Numerical investigation is made to study the effects of natural convection on the formation of macrosegregation of a Pb-Sn alloy solidification process in a 2-D confined rectangle mold. The governing equations are calculated using previous continuum models with SIMPLE algorithm doring the solidification process. In addition. to track the solid-liquid interface with time variations. the moving boundary condition Is adopted and irregular interface shapes are treated with Boundary-Fitted Coordinate system. As the temperature reduce from the liquidus to the solidus, the liquid concentration of Sn. the lighter constituent, increases. Then the buoyancy-driven flow due to temperature and liquid composition gradients, called thermosolutal convection or double diffusion, occurs in the mushy region and forms the complicated macrosegregation maps. Related to this phnomena, effects on the macrosegregation formation depending on the cooling condition and gravity values are described.

• Journal of Information Display
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• v.8 no.4
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• pp.1-4
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• 2007

In the present study, we propose Monte Carlo simulation that takes into consideration the interface phenomena between liquid crystal and substrate. We use rigid model molecules of liquid crystal and substrate. Interface is generated using potential field that induces decomposition of molecules. We use hard spherocylinders as model liquid crystal molecules. Substrate is modeled as region composed of shorter spherocylinders. Our results show that there is a case in which nematic order is reinforced in the vicinity of rubbed substrate.

• Journal of ILASS-Korea
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• v.6 no.2
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• pp.29-36
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• 2001

Vortices terminating at free surface have been investigated extensively. however. are focused on surface parallel vortices and little has been known about surface normal vortex or columnar vortex. Visualized experimental results utilizing LlF technique are discussed for the purpose of characterization of columnar vortex interacting with a clean and a contaminated free surfaces and a solid body interface in the present investigation. The results reveal that surface tension changes due to surface contamination although bulk viscosity remains constant and eventually the behavior of a columnar vortex interacting with a contaminated free surface and a solid body interface are totally different from the clean free surface case.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1558-1563
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• 2004

This work applies the nonequilibrium molecular dynamics simulation method to study a Lennard-Jones liquid thin film suspended in the vapor and calculates the thermal conductivity by linear response function. As a preliminary test, the thermal conductivity of pure argon fluid are calculated by nonequilibrium molecular dynamics simulation. It is found that the thermal conductivity decrease with decreasing the density. When both argon liquid and vapor phase are present, the effects of the system temperature on the thermal conductivity are investigated. It can be seen that the thermal conductivity of liquid-vapor interface is constant with increasing the temperature

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.1 s.232
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• pp.159-168
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• 2005

In recent studies, it was reported that there existed the temperature discontinuity at a liquid-vapor interface in an equilibrium state. However, from the viewpoint of the classical thermodynamics, it is highly questionable result although considering that the experiments related with a boundary layer is very difficult due to the extremely thin thickness of it. To clarify whether the temperature discontinuity over a liquid-vapor interface really exists, the computer simulations were performed. From the simulation results, it could be concluded that the misconception in a temperature calculation might result in non-uniform temperature distributions over an interface under an equilibrium state.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.1
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• pp.17-24
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• 2003

A mathematical model of the hydrodynamic and heat transfer performances of two-phase flow (gas-liquid) in thin film region of micro channel is proposed. For the formulation of modeling, the flow of the vapor phase and the shear stress at the liquid-vapor interface are considered. In this work, disjoining pressure and capillary force which drive the liquid flow at the liquid-vapor interface in thin film region are adopted also. Using the model, the effects of the variations of channel height and heat flux on the flow and heat transfer characteristics are investigated. Results show that the influence of variation of vapor pressure on the liquid film flow is not negligible. The heat flux in thin-film region is the most important operation factor of micro cooler system.

• Journal of Korea Foundry Society
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• v.18 no.3
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• pp.234-239
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• 1998

Unidirectional solidification of $Al-CuAl_2$ eutectic composites was studied under the condition of forced convection by vibration. It has been shown that thermal gradient for solid is different from that for liquid during solidification under force convection by vibration. With increase of vibration, mobility of liquid increases, but decreases with decreasing vibration. The rate of solidification is very high initially, and decreases suddenly. For further solidification, the rate of solidification decrceases slowly, and shows a L-type behavior. The mechanical vibration during solidification effects efficiently on nucleation, and induces a forced convection in liquid. By the forced convection, great thermal gradient of liquid interface between solid and liquid can be obtained. The amount of solute near the interface also decreases as solute distribution is improved by the forced convection.