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직교 격자를 이용한 저 레이놀즈 수에서의 다중 배치된 실린더의 VIV 해석
한명륜(M. R. Han),안형택(H . T. Ahn) 한국전산유체공학회 2010 한국전산유체공학회 학술대회논문집 Vol.2010 No.11
In this paper, the vortex-induced vibration of circular cylinders is studied using the immersed boundary method on the Cartesian mesh. The Reynolds numbers considered in this study is from 100 to 200. When multiple circular cylinders are arranged side-by-side or tandemly, the vortex shedding behind of the cylinders and the flow-induced motion are investigated. The staggered MAC grid method, which is typical grid system for the Cartesian mesh, and pressure correction method are applied for solving the incompressible Navier-Stokes equations. The body motion is described by immersed boundary technique that has advantages for moving oject in the simulation domain. It is also discussed for the computation noise when body is moving with IBM. The Predictor/Corrector method is used for simulating the nonlinear response of body surrounded by the fluids.
직교 격자를 이용한 저 레이놀즈 수 유동장내 다중 배치된 실린더의 와유기 진동 해석
한명륜(Myung Ryoon Han),안형택(Hyung Teak Ahn) 한국전산유체공학회 2011 한국전산유체공학회지 Vol.16 No.1
In this paper, the vortex-induced vibration of circular cylinders is studied using the immersed boundary method on the Cartesian mesh. The Reynolds numbers considered is from 100 to 200. Using the configuration of tendemly arranged multiple circular cylinders, the vortex shedding behind of the cylinders and their flow-induced motion are investigated. The staggered MAC grid arrangement, which is the typical grid system for the incompressible flow on the Cartesian meshes, is utilized. Pressure correction method is applied for solving the divergence-free incompressible velocity field. The body motion is described by immersed boundary technique that has advantages for moving object on the fixed computational domain. It is also discussed for the computational noise in hydrodynamic forces when body motion is represented by the immersed boundary method. The Predictor/Corrector method is used for simulating the nonlinear response of the elastically mounted cylinder excited by vortex-shedding.
한명륜(Myung-Ryun Han),김명환(Myung-Hwan Kim) 한국식품영양과학회 2005 한국식품영양과학회지 Vol.34 No.5
본 연구는 물리적 전분 변성방법으로서 유체전단 균질기와 초음파 균질기를 이용하여 쌀 전분의 크기 감소로 인한 물리적 변성 쌀 전분의 이화학적 특성을 분석하는데 있다. 물 대 전분의 비가 5:1이고, 20,500 rpm 조건의 유체전단 균질기와 5초의 파동과 40 ㎑의 주파수조건의 초음파 균질기로 각각 10분간 처리하였을 때 생전분과 호화전분의 크기를 1/3수준으로 줄일수 있었으며 동시에 균질화시킬 수가 있었다. 균질화된 전분과 균질화된 호화전분은 대조구에 비하여 높은 값의 비표면적, 광투과도, 용해도 및 팽윤력을 나타내었으며, 매우 큰 폭의 겉보기 점도 감소를 보였다. 반면에, 초음파 균질기로 처리한 변성전분의 호화과정은 대조구에 비하여 어려웠으나 유체전단 균질기의 경우는 대조구와 비슷하였다. The objectives of this research were to analyze physicochemical properties of physically modified rice starch which was prepared by hydro-shear homogenizer and ultrasonic homogenizer. The 5:1 of water to starch ratio, 20,500 rpm of hydro-shear homogenizer, and 5 sec of pulse and 40 ㎑ of frequency of ultrasonic homogenizer, which were operated for 10 min. The 1/3 of size reduction of raw rice starch and gelatinized rice starch, and reduced of particle size were achieved by above processing conditions. The homogenization of raw rice starch and gelatinized rice starch were higher values of specific area, transmittance, solubility and swelling power than control. While, these had lower value of apparent viscosity than control. In raw rice starch, the gelatinization characteristics of ultrasonic homogenizer treated rice starch had some higher values of gelatinization temperature, peak temperature and enthalpy than those of control. While, those of hydro-shear homogenizer treated rice starch had similar values to those of control.