• Journal of the Korean Society for Industrial and Applied Mathematics
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• 제19권1호
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• pp.57-68
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• 2015

When a straight channel formed by two parallel porous plates, through which two immiscible liquids occupying different heights are flowing a secondary motion is set up. The motion is caused by moving the upper plate with a uniform velocity about an axis perpendicular to the plates. The solutions are exact solutions. Here we discuss the effect of suction parameter and the position of interface on the flow phenomena in case of Couette flow. The velocity distributions for the primary and secondary flows have been discussed and presented graphically. The skin-friction amplitude at the upper and lower plates has been discussed for various physical parameters.

• 전기전자학회논문지
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• 제18권4호
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• pp.463-470
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• 2014

In stratified flows of two immiscible liquids, due to the vibration in a pipe, the shape of the interface is not always periodic and it causes the different end points of the interfacial boundary. In this case the performance is not good. To solve this, in this paper, the hybrid-type Fourier series is proposed, which consists of both the polynomial and the trigonometric terms. Under the stationary interfacial boundary during acquiring a full set of voltage data, the performance of the proposed method is evaluated through the numerical experiments. The results show that the proposed method performs better than the conventional Fourier series in estimating the interfacial boundary.

• Nuclear Engineering and Technology
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• 제52권6호
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• pp.1172-1179
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• 2020

As a Lagrangian particle method, Moving Particle Semi-implicit (MPS) method has great capability to capture interface/surface. In recent years, the multiphase flow simulation using MPS method has become one of the important directions of its developments. In this study, some key methods for multiphase flow have been introduced. The interface tension model in multiphase flow is modified to maintain the smooth of the interface and suitable for the three-phase flow. The mass transfer at immiscible liquid interface entrained by single bubble which could occur in Molten Core-Concrete Interaction (MCCI) has been investigated using this particle method. With the increase of bubble size, the height of entrainment column also increases, but the time of film rupture is slightly different. With the increase of density ratio between the two liquids, the height of entrained column decreases significantly due to the decreasing buoyancy of the denser liquid in the lighter liquid. In addition, the larger the interface tension coefficient is, the more rapidly the entrained denser liquid falls. This study validates that the MPS method has shown great performance for multiphase flow simulation. Besides, the influence of physical parameters on the mass transfer at immiscible interface has also been investigated in this study.

• 대한기계학회논문집B
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• 제28권6호
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• pp.682-687
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• 2004

Y-junction microchannels are widely used as a flew mixer. Fluids are entered from two branch channels and merged together at a combined channel. In this study, we suggest a simple method to create the fluid digitization using flow instability phenomena. Two immiscible liquids (water/oil) are infused continuously to each Y-junction inlets. Because of the differences in fluid and flow properties at the interface, oil droplet is formed automatically followed by flow instability. In order to clarify the hydrodynamic aspects involved in oil droplet formation, a quantitative flow visualization study has performed. Highly resolved velocity vector fields are obtained by a micro-PIV technique, so that detail flow structures around the droplet are illustrated. In this study, fluorescent particles were mixed with water only for visualization of oil droplet and velocity field measurement in water flow.

• 대한기계학회논문집B
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• 제27권5호
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• pp.644-654
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• 2003

An analytical solution for a vertically stratified viscous flow in a microchannel with a rectangular cross-section is constructed, assuming fully developed laminar flow where the interfaces between the fluid layers are flat. Although the solution is for n-layer flow, restricted results to symmetrical three-layer flow are presented to investigate the effects of the viscosity and thickness ratios of the fluid layers and the aspect ratio of the microchannel on the flow field. Relations between the flow rate and thickness ratios of the fluid layers with varying viscosity distributions are found, considering the cross -sectional velocity profiles which vary noticeably with the three parameters and differ significantly from the velocity profiles of the flow between infinite parallel plates. Interfacial instability induced by the viscosity stratification in the microchannel is discussed referring to previous studies on the instability analysis for plane multilayer flow. Exact solution derived in the present study can be used for examining a diffusion process and three -dimensional stability analysis. More works are needed to formulate the equations including the effects of interfacial' tension between immiscible liquids and surface wettability which are important in microscale transport phenomena.

• 한국응용과학기술학회지
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• 제31권4호
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• pp.623-627
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• 2014

에멀젼은 섞이지 않은 두 물질을 분산시스템으로 혼합시켜 놓은 것이다. 에멀젼의 점도에 영향을 미치는 인자는 유화입자 크기, 연속상 및 분산상 종류, 연속상과 분산상의 비, 유화제 종류 및 유화기기 등 다양한 요소들이 있다. 본 연구에서는 오일 극성도에 따라 에멀젼의 점도 변화를 관찰하였고 이를 유기개념도를 이용하여 해석하였다. 탄화수소계, 에스테르계 및 실리콘계 오일을 사용하여 에멀젼을 제조하여 점도를 측정하였다. 오일 극성도가 높을수록 계면에 위치하는 유화제 및 유화안정제의 양이 적어지기 때문에 점도는 감소하였다. 극성 오일간 극성도를 수치적으로 비교하기 위해 유기개념도 이용하였으며 유기개념도상의 해석과 에멀젼의 점도 측정 결과가 실리콘 오일을 제외하고는 모두 일치하였다.