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PIV를 이용한 바탕회전하에서 회전요동하는 직사각형 용기 내의 유동해석
서용권,최윤환,김성균,이두열,Suh, Yong-Kweon,Choi, Yoon-Hwan,Kim, Sung-Kyun,Lee, Du-Yeol 대한기계학회 2000 大韓機械學會論文集B Vol.24 No.6
In this paper, we show the numerical and the experimental results of two-dimensional fluid motions inside a rectangular container subjected to a background rotation added by a rotational oscillation. In the PlY experiment we apply a new algorithm, new three step search(NTSS), to the velocity calculation. In the numerical computation, the linear Ekman-pumping model was used to take the bottom friction effect into account. It was found that it well produces the experimental results at low e number.
마이크로채널 내 블록의 정렬과 구조변경에 따른 교반특성
서용권,허형석,Suh, Yong-Kweon,Heo, Hyeung-Seok 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.7
Numerical study on stirring characteristics in a microchannel with blocks arranged periodically has been performed. Viscous flows through the microchannel is simulated three-dimensionally using a commercial code, FLUENT 6.0. Focus is given to the effect on the stirring characteristics of the geometric factors including the pitch, height and angle of the block arrangement. The numerical results at low Reynolds numbers show that the particles' trajectories in the microchannel heavily depend on the block arrangement. A nonlinear dynamical tool, i.e. Lyapunov exponent, was used in analysing the mixing effect. It was found that the mixing is the most effective at a certain combination of parameter values.
서용권,Suh, Yong-Kweon 대한기계학회 1993 대한기계학회논문집 Vol.17 No.7
Two-dimensional spin-up in a rectangular domain is analysed by the numerical computation of the Navier-Stokes equations. The cells are in most cases generated by the vorticity developed near the uper and lower surfaces. Moreover, the movement and interaction of those vortices play a key role in establishing the quasi-steady state. The critical phenomena observed in the previous experiment turns out to be caused by the critical movement of the vortices.
배경회전하에서 형성되는 주기적 유동의 3차원 수치해석과 실험
서용권,박재현,Suh, Yong-Kweon,Park, Jae-Hyun 대한기계학회 2003 大韓機械學會論文集B Vol.27 No.5
We present numerical and experimental results of periodic flows inside a rectangular container under a background rotation. The periodic flows are generated by changing the speed of rotation periodically so that a time-periodic body forces produce the unsteady flows. In numerical computation, a parallel-computation technique with MPI is implemented. Flow visualization and PIV measurement are also performed to obtain velocity fields at the free surface. Through a series of numerical and experimental works, we aim to clarify, if any, the fundamental reasons \ulcornerf discrepancy between the two-dimensional computation and the experimental measurement, which was detected in the previous study for the same flow model. Specifically, we check if the various assumptions prerequisite for the validity of the classical Ekman pumping law are satisfied for periodic flows under a background rotation.
원통 내 스핀업 유동에서의 관성진동에 관한 수치해석적 연구
서용권(YONG KWEON SUH) 한국해양공학회 2001 韓國海洋工學會誌 Vol.15 No.3
In this paper we present the aspect of inertial oscillation typically observed in the spin-up of fluids at low Rossby numbers in a circular cylinder. Numerical computations for the quasi three-dimensional equation as well as the one-dimensional equation are performed to estimate the predictability of the one-dimensional equation with Ekman pumping/suction models. It is assumed that the discrepancy between the two results may be attributed to the inertial oscillation. The detailed analysis to the numerical results reveals that the axial plane is dominated by a comparatively strong oscillatory flows caused by the inertial oscillation. In view of the fact that the time-averaged flow field however agrees to the Taylor-Proudman theorem, it is recommended that further analysis is needed to obtain an improved one-dimensional model like the Reynolds-averaged Navier-Stokes equation for turbulent flows.
에크만 분출 모델을 이용한 캐버티 내의 비정상 유동특성에 관한 수치해석
서용권(Yong-Kweon Suh),박춘근(Chun-Kun Park),최윤환(Yoon-Hwan Choi),문종춘(Jong-Chun Moon) 한국해양공학회 1997 韓國海洋工學會誌 Vol.11 No.4
A two dimensional shallow-water flow around a cavity driven by a sinusoidally oscillating external flow was studied numerically with an Ekman pumping model. A container model of "T" shape was constructed in the numerical computation for comparison with the experimental observation. The material transport in the external region is in good agreement with the experimentally recorded particle trajectories. It turns out that two large coherent vortices situated in the exterior region of the cavity are responsible for clockwise and counterclockwise drift motions, in large scale, of particles. The Ekman pumping model suggested in this study was found to be satisfactory.
순환골재 생산 공정상에서 공기유동을 이용한 토분에 포함된 이물질 제거장치에 관한 연구
서용권(Yong-Kweon Suh),허성규(Seong-Gyu Heo),박용기(Yong-Gi Park) 한국가시화정보학회 2006 한국가시화정보학회지 Vol.4 No.2
In this paper, we present flow patterns around and performance of an air-flow separator by using the numerical analysis. With this separator, particles of different density are to be separated by using the drag force from the air flow. The low-density particles are designed to be separated by using inhalation through holes on a rotating drum. To obtain the flow informations needed for determining the proper design parameters, we have performed numerical simulations by using a commercial code, ANSYS CFX. Various parameter set was tested and it was found that depending on the design of drums there exist critical parameter set regarding the attachment of light particles on the drum, which is prerequisite for the separation of materials. We present here the possibility of using the present design in separation of particles mixed in the clod for use in recycling.
서용권(Yong Kweon Suh),여창호(Chang Ho Yeo) 한국가시화정보학회 2004 한국가시화정보학회지 Vol.2 No.2
Theoretical and numerical studies are given to the sink flows within a rotating circular tank driven by the fluid withdrawal from a bottom circular hole. It was found that, when the upper free surface was set with no-slip boundary conditions, the Ekman boundary-layer develops not only above the bottom surface but under the top surface. The sink fluid is coming from the two Ekman layers, and the mass transfer from the bulk, inviscid region is dependent on the rotational speed. It is also remarkable to see that all the fluid gathered along the axis flows in a form of rapidly rotating fluid column having almost the same diameter as the bottom hole.
수정진동자를 사용한 점탄성 유체의 점성계수와 전단 탄성계수 측정에 관한 이론해석
서용권(Yong Kweon Suh),김영한(Young Han Kim) 대한기계학회 2008 大韓機械學會論文集B Vol.32 No.7
Quartz crystal oscillator is frequently used in measuring a very small amount of mass attached to or adsorbed on the surface of an electrode on the quartz plate. The physical principle is that the resonance frequency of the shear vibration of the quartz caused by an applied electric field is a function of the mass. Recently, effort has been tried to measure physical properties of viscoelastic fluids, such as viscosity and shear modulus. This paper presents useful formula that can be used in estimating the properties of viscoelastic fluids. Important finding in this analysis is that the formula can produce multiple values for the physical properties of the viscoelastic materials.