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REFERENCE LINKING PLATFORM OF KOREA S&T JOURNALS
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Transactions of the Korean Society of Mechanical Engineers B
Journal Basic Information
Journal DOI :
The Korean Society of Mechanical Engineers
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Volume & Issues
Volume 28, Issue 12 - Dec 2004
Volume 28, Issue 11 - Nov 2004
Volume 28, Issue 10 - Oct 2004
Volume 28, Issue 9 - Sep 2004
Volume 28, Issue 8 - Aug 2004
Volume 28, Issue 7 - Jul 2004
Volume 28, Issue 6 - Jun 2004
Volume 28, Issue 5 - May 2004
Volume 28, Issue 4 - Apr 2004
Volume 28, Issue 3 - Mar 2004
Volume 28, Issue 2 - Feb 2004
Volume 28, Issue 1 - Jan 2004
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The Basic Study on the Technique of Fluid Flow Analysis Using the Immersed Boundary Method
Yang, Seung-Ho ; Ha, Man-Yeong ; Park, Il-Ryong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 28, issue 6, 2004, Pages 619~627
DOI : 10.3795/KSME-B.2004.28.6.619
In most industrial applications, the geometrical complexity is combined with the moving boundaries. These problems considerably increase the computational difficulties since they require, respectively, regeneration and deformation of the grid. As a result, engineering flow simulation is restricted. In order to solve this kind of problems the immersed boundary method was developed. In this study, the immersed boundary method is applied to the numerical simulation of stationary, rotating and oscillating cylinders in the 2-dimensional square cavity. No-slip velocity boundary conditions are given by imposing feedback forcing term to the momentum equation. Besides, this technique is used with a second-order accurate interpolation scheme in order to improve the accuracy of flow near the immersed boundaries. The governing equations for the mass and momentum using the immersed boundary method are discretized on the non-staggered grid by using the finite volume method. The results agree well with previous numerical and experimental results. This study presents the possibility of the immersed boundary method to apply to the complex flow experienced in the industrial applications. The usefulness of this method will be confirmed when we solve the complex geometries and moving bodies.
Large Eddy Simulation of Turbulent Passive Scalar in a Channel with Strong Wall Injection
Kim, Hak-Jong ; Na, Yang ;
Transactions of the Korean Society of Mechanical Engineers B, volume 28, issue 6, 2004, Pages 628~637
DOI : 10.3795/KSME-B.2004.28.6.628
The present study investigates the performance of dynamic mixed model (DMM; Zang et ai.) in a channel with strong wall injection through a Large eddy simulation (LES) technique. The DMM results are compared with those of DNS and the results obtained with popular dynamic Smagorinsky model (DSM). Better agreement is achieved when using the DMM with box filter than DSM and coarse DNS in predicting the first and second order statistics as well as large-scale structures of velocity and temperature fields. Such favorable features of DMM are attributed to the fact that it explicitly calculates the modified Leonard stress term and only models the remaining cross and the SGS Reynolds stress terms and, thus, it reduces the excessive burden put on the model coefficient of DSM. Also it is demonstrated that the DMM can be successfully extended to the prediction of temperature (passive scalar) field where strong streamwise inhomogeneity exists.
Development and Analysis for Micro Actuator Using Buckling Membrane and Phase Change
Song, Kwi-Eun ; Kim, Jeong-Sik ; Kim, Kwang-Ho ; Lee, Yoon-Pyol ;
Transactions of the Korean Society of Mechanical Engineers B, volume 28, issue 6, 2004, Pages 638~645
DOI : 10.3795/KSME-B.2004.28.6.638
A new micro actuation concept is introduced and studied in this paper. This idea is based on the thermo-pneumatic actuation principle. In order to improve the performance of a conventional thermo-pneumatic actuator, the idea of bistable buckling is added. By using a membrane which has the bistable buckling characteristics, the working pressure difference can be increased and as a result the work output can be increased. The analysis model for each phenomenon, bistable buckling and phase change, are suggested and the each model is verified with experimental data. From the comparison of the theoretical prediction with the experimental results, it can be concluded that these models are useful for such micro actuator analysis.
A Study on the Formation of Fouling in a Heat Exchanging System for River Water
Sung, Sun-Kyung ; Suh, Sang-Ho ; Roh, Hyung-Woon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 28, issue 6, 2004, Pages 646~651
DOI : 10.3795/KSME-B.2004.28.6.646
When the water flowing inside of the heat transfer equipments such as heat exchangers, condensers, and boilers is heated, calcium, magnesium sulfate, and other minerals in the water are deposited and built up for scales on the heat transfer surfaces. When those scales accumulate on the heat transfer surfaces, their performance of the heat transfer become progressively reduced due to the increase of the heat transfer resistance. The mechanism of this reduced heat transfer is called fouling. This study investigated the formation of the fouling in a heat exchanger with river and tap water flowed inside of it as a coolant. In order to visualize the formation of the fouling and to measure the fouling coefficients, a lab-scale heat exchanging system was used. Based on the experimental results, it was found that the formation of fouling for river water was quite different with the formation for tap water.
Movement of a Horizontal Vortex Ring in a Circular Cylinder
Suh, Yong-Kweon ; Yeo, Chang-Ho ;
Transactions of the Korean Society of Mechanical Engineers B, volume 28, issue 6, 2004, Pages 652~658
DOI : 10.3795/KSME-B.2004.28.6.652
In this paper, we report the numerical and experimental solutions of the axi-symmetric flows in the axial plane driven by an impingement of fluid from the bottom wall of a circular cylinder. We managed to visualize successfully the flow pattern shown on the vertical plane through the container axis. The numerical results are shown to compare well with the experimental results for the case of infinity Rossby number. The satisfactory agreement between the two results was possible when in the numerics the free surface was treated as a solid wall so that a no-slip condition was applied on the surface. The numerical solutions reveal that inertial oscillation plays an important role at small Rossby numbers, or at a larger background rotation.
X-ray Micro-Imaging Technique for Simultaneous Measurement of Size and Velocity of Micro-Bubbles
Kim, Seok ; Lee, Sang-Joon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 28, issue 6, 2004, Pages 659~664
DOI : 10.3795/KSME-B.2004.28.6.659
It is important to measure precisely the size and velocity of micro-bubbles used in various field. The synchrotron X-ray micro-imaging technique was employed to measure the size and velocity of micro-bubbles moving in an opaque tube simultaneously. Phase contrast images were obtained at interfaces of micro-bubbles between water and air due to their different refractive indices. The X-ray micro-imaging technique was found to measure an optical fiber with an accuracy of 0.2%. Micro-bubbles of 20∼60
diameter moving upward in an opaque tube (
＝2.7mm) were tested to measure bubble size and up-rising velocity. For DI water, the measured velocity of micro-bubbles is nearly proportional to the square of bubble size, agreed well with the theoretical result. In addition, the synchrotron X-ray micro-imaging technique can measure accurately the size and velocity of several overlapped micro-bubbles.
Modeling for Prediction of Frost Formation Phenomena on a Cold Plate
Yang, Dong-Keun ; Kim, Jung-Soo ; Lee, Kwan-Soo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 28, issue 6, 2004, Pages 665~671
DOI : 10.3795/KSME-B.2004.28.6.665
A mathematical model is presented to predict the frost properties and heat and mass transfer within the frost layer formed on a cold plate. The model consists of the laminar flow equations for air-side and the empirical correlation of local frost density. The correlation of local frost density used in this study is obtained from various experimental conditions by considering frosting parameters. The numerical results are compared with experimental data to validate the model, and agree well with experimental data within a maximum error of 9%.
Numerical Study on the Vortex Evolution from a Sharp-Edged, Wall-Mounted Obstacle
Hwang, Jong-Yeon ; Yang, Kyung-Soo ;
Transactions of the Korean Society of Mechanical Engineers B, volume 28, issue 6, 2004, Pages 672~681
DOI : 10.3795/KSME-B.2004.28.6.672
Direct numerical simulation was carried out to study the vortical structures of the flow around a wall-mounted cube in a channel at Re
Micro-PIV Measurement of Water/Oil Two Phase Flow in a Y-Junction Microchannel
Yoon,Sang-Youl ; Ko, Choon-Sik ; Kim, Kyung-Chun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 28, issue 6, 2004, Pages 682~687
DOI : 10.3795/KSME-B.2004.28.6.682
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.
A Numerical Study on Nonlinear Dynamic Behavior of Diffusive-Thermal Instability in Diluted CH
Conterflow Diffusion Flames
Sohn, Chae-Hoon ;
Transactions of the Korean Society of Mechanical Engineers B, volume 28, issue 6, 2004, Pages 688~696
DOI : 10.3795/KSME-B.2004.28.6.688
Nonlinear dynamic behavior of diffusive-thermal instability in diluted CH
diffusion flames is numerically investigated by adopting detailed chemistry and transport. Counterflow diffusion flame is adopted as a model flamelet. Particular attention is focused on the pulsating-instability regime, which arises for Lewis numbers greater than unity, and the instability occurs at high strain rate near extinction condition in this flame configuration. Once a steady flame structure is obtained for a prescribed value of initial strain rate, transient solution of the flame is calculated after a finite amount of strain-rate perturbation is imposed on the steady flame. Transient evolution of the flame depends on the initial strain rate and the amount of perturbed strain rate. Basically, the dynamic behaviors can be classified into two types, namely non-oscillatory decaying solution and diverging solution leading to extinction. The peculiar oscillatory solution, which has been found in the previous study adopting one-step chemistry and constant Lewis numbers, is net observed in this study, which is attributed to both convective flow and preferential diffusion effects.
Theoretical Analysis on Bifurcation Behavior of Catalytic Surface Reaction on Nonadiabatic Stagnation Plane
Lee, Su- Ryong ;
Transactions of the Korean Society of Mechanical Engineers B, volume 28, issue 6, 2004, Pages 697~704
DOI : 10.3795/KSME-B.2004.28.6.697
Bifurcation behavior of ignition and extinction of catalytic reaction is theoretically investigated in a stagnation-point flow. Considering that reaction takes place only on the catalytic surface, where conductive heat losses are allowed to occur, activation energy asymptotics with a overall one-step Arrhenius-type catalytic reaction is employed. For the cases with and without the limiting reactant consumption, the analysis provides explicit expressions, which indicate the possibility of multiple steady-state solution branches. The difference between the solutions with and without reactant consumption is in the existence of an upper solution branch, and the neglect of reactant consumption is inappropriate for determining extinction conditions. For larger values of reactant consumption, the solution response is all monotone, suggesting that multiple solutions are not possible. It is shown that bifurcation Damkohler numbers increase (decrease) with increasing of conductive heat loss (gain) on the catalytic surface, which means that smaller (larger) values of the strain rate allow the surface reaction to tolerate larger heat losses (gains). Lewis number of the limiting reactant can also significantly affect bifurcation behavior in a similar way to the effect of heat loss.
A Study on the Inverse Analysis of Surface Radiation in a Cylindrical Enclosure
KIm, Ki-Wan ; Baek, Seung-Wook ; Ryou, Hong-Sun ;
Transactions of the Korean Society of Mechanical Engineers B, volume 28, issue 6, 2004, Pages 705~712
DOI : 10.3795/KSME-B.2004.28.6.705
An inverse boundary analysis of surface radiation in an axisymmetric cylindrical enclosure has been conducted in this study. Net energy exchange method was used to calculate the radiative heat flux on each surface, and a hybrid genetic algorithm was adopted to minimize an objective function, which is expressed by sum of square errors between estimated and measured or desired heat fluxes on the design surface. We have examined the effects of the measurement error as well as the number of measurement points on the estimation accuracy. Furthermore, the effect of a variation in one boundary condition on the other boundary conditions was also investigated to get the same desired heat flux and temperature distribution on the design surface.
Numerical Analysis of Two-Dimensional Motion of a Freely Falling Circular Cylinder in an Infinite Fluid
Namkoong, Kak ; Choi, Hyoung-Gwon ; Yoo, Jung-Yul ;
Transactions of the Korean Society of Mechanical Engineers B, volume 28, issue 6, 2004, Pages 713~725
DOI : 10.3795/KSME-B.2004.28.6.713
The two-dimensional motion of a freely falling circular cylinder in an infinite fluid is investigated numerically using combined formulation. The effect of vortex shedding on the motion of a freely falling cylinder is clearly seen: as the streamwise velocity of the cylinder increases due to gravity, the periodic vortex shedding induces a periodic motion of the cylinder. This motion in turn affects the flow field, which is manifested by the generation of the angular velocity vector of the cylinder parallel to the cross product of the gravitational acceleration vector and the transverse velocity vector of the cylinder. A correlation of St-Re relationship for a freely falling circular cylinder is drawn from the present results. The Strouhal number for a freely falling circular cylinder is found to be smaller than that for a fixed circular cylinder when the two Reynolds numbers based on the streamwise terminal velocity of a freely failing circular cylinder and the free stream velocity of a fixed one are the same. From "thought experiments", it is shown that the transverse motion of the cylinder plays a crucial role in reducing the Strouhal number and has an effect of reducing the Reynolds number from the viewpoint of the pressure coefficient. The mechanism of this reduction in the Strouhal number is revealed by the fact that the freely falling cylinder experiences a smaller lift force than the fixed one due to the transverse motion resulting in the retardation of the vortex shedding.
Generation of Microcellular Foams in Viscoelastic Polymer Solutions
Kang, Sung- Lin ; Kim, Ki-Young ; Kwak, Ho-Young ;
Transactions of the Korean Society of Mechanical Engineers B, volume 28, issue 6, 2004, Pages 726~733
DOI : 10.3795/KSME-B.2004.28.6.726
The growth of the critical size bubble by diffusion process in viscoelastic medium was treated by an integral method for the concentration boundary layer adjacent to the bubble wall. In this study, we obtained a set of the first order time dependent equations to obtain bubble radius and gas pressure inside the bubble simultaneously. The calculated final cell sizes depending on the initial saturation pressure are in close agreement with the observed ones. The governing equations developed in this study may be used in polymer processing of microcellular foams.
An Experimental Study on the Aerodynamic Effects Generated by a Train Passing Rear by Platform
Kim, Dong-Hyeon ; Kwon, Hyeok-Bin ; Kim, Do-Hoon ; Kim, Moon-Hun ; Song, Moon-Shuk ;
Transactions of the Korean Society of Mechanical Engineers B, volume 28, issue 6, 2004, Pages 734~739
DOI : 10.3795/KSME-B.2004.28.6.734
The aerodynamic effect on platform during the train passage, the results of field test on the high-speed railway platform are discussed and the whole test results and conclusions are synthesized. The field test for the high-speed railway have been conducted on the Osong temporary platform in the newly constructed Seoul-Busan high-speed line and total 12 measurements have been conducted for G7 train and KTX train. The results shows that the high-speed trains have similar aerodynamic characteristics and have far better characteristics referring to the conventional trains such as Saemaul and Mugungwha trains. To discuss the actual aerodynamic effects on the platform at its own operational speed, Beaufort wind scale have been introduced and the criteria for the safety on railway platform has also been discussed.