• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.5
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• pp.1083-1096
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• 2015

This study utilised Computational Fluid Dynamics(CFD) for preliminary assessment of mixing efficiencies of 2-phase fluids in a pipe at which a slurry flow and an injected solidifier join, for the purposes of reducing trial-and-error-based instances of physical experiments and conducting the overall research in an economical way. Using OpenFOAM$^{(R)}$, we simulated behavior of 3-phase fluids under 18 different settings generated by changing diameters of a dredged soil transportation pipe, a quality improving material injection pipe and the confluence angle. While difference in mixing efficiencies amongst the instances was insignificant, discernible boundary layers amongst the materials were observed in all of the instances. In order to break the boundary layers, we designed a substructure inside a pipe and found out that it could remarkably improve mixing efficiencies particularly for short distance applications.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.5
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• pp.2610-2616
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• 2014

An ejector is a kind of pump which is using pressure energy of high pressure fluid. This study aims to investigate performance influencing according to change the ejector mixing section shape using CFD simulation by Finite Volume Method. Optimum conditions were suggested 3 kind of variable such as nozzle diameter, nozzle length, distance from nozzle tip to the diffuser inlet. The results, It was confirmed that the diameter of the nozzle was the greatest effect in performance of the ejector. The diameter of the nozzle get smaller, mixing ratio was increased. On the other hand, nozzle length, distance from nozzle tip to the diffuser inlet had little effect on performance. It was proposed specific Mixing section, Nozzel diameter 23.8mm using the Artificial Neural Network.

• 한국전산유체공학회:학술대회논문집
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• 2005.04a
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• pp.1-13
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• 2005

Fluid flows within microchannels are characterized by low Reynolds numbers. Therefore the effect of mixing is a crucial factor in design of the channels. Since the action of the electro-osmotic or magnetic forces used in the mixing enhancement is usually periodic in the three-dimensional channel configuration, use of the various concepts of chaotic advection is reasonable in the quantification of the stirring effect. In this paper, the details of the method of material-stretching mapping is explained. The actual application of the method to the screw extruder is also presented.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.30 no.8
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• pp.45-53
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• 2001

열적 성질을 가지는 각종 용질을 물을 주체로 한 열매체 등에 혼합 분산시킴으로써 그 열매체인 유체의 성질을 바꾸어 다원적 기능성을 가지도록 한 기능성 열유체의 열에너지 수송성에 대해 살펴보고자 한다.

• 한국전산유체공학회:학술대회논문집
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• 2009.04a
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• pp.112-115
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• 2009

In this paper, flow simulation algorithms for utilizing unstructured hybrid meshes are introduced. First, various types of meshes are introduced. Advantages and disadvantages of each type of meshes are discussed. Unstructured hybrid mesh approach, that is best suited for high speed viscous flow simulation, is presented. Lastly, various types of flow simulations using unstructured hybrid meshes are introduced.

• 유체기계공업학회:학술대회논문집
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• 2006.08a
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• pp.301-304
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• 2006

This paper presents a review of the important recent literature available in the area of micro-channel flow analysis and mixing. The topics covered include the physics of flows in micro-channels and integrated simulation of micro-channel flows. Also the flow control models and electro-kinetically driven micro-channel flows are explained. A comparison of various mixing principles in micro-channels are provided in sufficient detail.

• Journal of the Korea Computer Graphics Society
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• v.23 no.4
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• pp.11-19
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• 2017

We propose a new pipeline of fluid surface reconstruction that incorporates hybrid SDF(signed distance fields) and adaptive fluid surface techniques to finely reconstruct liquid-solid mixed surfaces. Previous particle-based fluid simulation suffer from a noisy surface problem when the particles are distributed irregularly. If a smoothing scheme is applied to reduce the problem, sharp and detailed features can be lost by over-smoothing artifacts. Our method constructs a hybrid SDF by combining signed distance values from the solid and liquid parts of the object. We also proposed a method of adaptively reconstructing the surface of the fluid to further improve the overall efficiency. This not only shows the detailed surface of the solid and liquid parts, but also the detail of the solid surface and the smooth fluid surface when both materials are mixed. We introduce the concept of guiding shape and propose a method to get signed distance value quickly. In addition, the hybrid SDF and mesh reconstruction techniques are integrated in the adaptive framework. As a result, our method improves the overall efficiency of the pipeline to restore fluid surfaces.

• Korean Chemical Engineering Research
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• v.50 no.1
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• pp.66-71
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• 2012

We deal with a problem to determine experimentally as well as theoretically permeability of incompressible viscous flow through packed bed of bidisperse hard spheres in size. For the size ratios of large to small spheres ${\lambda}$=1.25 and 2, we set up bidisperse packing and measured porosity and permeability at various volumetric ratios of small to large spheres ${\gamma}$. Bidisperse packing shows lower porosity and permeability than monodisperse packing does. Variation of porosity as a function of ${\gamma}$ does not match with that of permeability. A theoretical expression for predicting permeability of a viscous flow for packed bed of bidisperse packing is derived based on calculation of drag force acting on each sphere and its predictions are compared with the experimental data and those from some relations previously suggested. It is found that our theory shows better agreement with experimental results than the previous studies and is proved to be quite simple and accurate in estimating the permeability.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3022-3029
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• 2015

This study presents experiments to visualize the internal flow and heat transfer characteristics of thermosyphon with immiscible of water-FC40 adopted as binary working fluid. Three different regimes depending on the amount of heat flux applied to the thermosyphon were observed: natural convection, pulse boiling, and continuous boiling. Boiling incipience took place in water, which has lower vapor pressure than FC40. During natural convection water was vaporized in liquid pool while liquid film flows were formed. On the other hand, meanwhile bubbles were generated in the liquid pool during pulse and continuous boiling, the binary working fluid of water-FC40 was observed as the mixture throughout a whole range of the thermosyphon.

• Korean Chemical Engineering Research
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• v.60 no.4
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• pp.613-619
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• 2022

The extended Maxwell-Wagner polarization model is employed to describe the ER(Electrorheological) behavior of bi-dispersed ER suspensions, and solutions to the equation of motion are obtained by dynamic simulation. Under the same particle volume fraction, it is found that the dynamic yield stresses of uniform size suspensions do not depend on the particle size. Compared with uniform size suspensions, the dynamic yield stress is reduced for ER fluids consisting of two kinds of particles with different sizes. Compared with the dynamic yield stress behavior, for ${\dot{\gamma}}^*$≧0.01 the shear stress shows different behaviors depending on the particle sizes and the raio of different size particles. The simulation results show the nonlinear ER behavior (∆_𝛕 ∝ Eⁿ, n ≈ 1.55) of the conducting particle ER suspensions.