http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
흐름에 대하여 橫方向으로 놓인 두 원통둘레의 Potential flow 硏究
徐龍權 영남이공대학 1981 論文集 Vol.10 No.-
This paper treats the potential flow of the ideal fluid passing the cylinders placed laterally. The Laplace equation is solved by adequate coordinate trans-formation and with boundary conditions. The stream function is calculated and graphed, after which pressure distribution on the body surface, the lift coefficient and the stagnation point are also deduced and shown on this paper. Followings are concluded from these results. 1) Stream lines are more inclined to the outer direction than those of the single cylinder. 2) The flow is the fastest in the midst of the two bodies. This makes the two cylinders attract each other and the attraction force increases as the two bodies got nearer. 3) Stagnation point goes toward the mid poind of the two cylinders as the two get nearer.
비정상 Navier-Stokes 방정식의 수치해석을 위한 다단계 외재법의 성능 비교
서용권,Seo,Yong-Gwon 대한기계학회 1997 大韓機械學會論文集B Vol.21 No.2
In this study, performance of the multi-stage explicit methods for numerical computation of the unsteady Navier-Stokes equations is investigated. Three methods under consideration are 1 st-, 2 nd-, and 4 th-order Runge-Kutta (R-K) methods. Compared in this estimation is stability, accuracy, and CPU time of each method. The computational codes developed are applied to the two-dimensional flow in a square cavity driven by an oscillating lid. It turned out that at Reynolds number 400, the 1 st-order R-K method is the best, while at 3200 the 2 nd-order R-K is recommended. At higher Reynolds numbers, it is conjectured that the 4 th-order R-K method will be the best algorithm among three due to its highest stability.
서용권,박준관,문종춘,김용균,Seo,Yong-Gwon,Park, Jun-Gwan,Mun, Jong-Chun,Kim, Yong-Gyun 대한기계학회 1997 大韓機械學會論文集B Vol.21 No.12
In this paper, a precise description is given to the basic theory as well as the detailed algorithms for the numerical treatment of the method of POD (proper orthogonal decomposition). This method is then applied to analysing the numerical solutions of one-dimensional shallow-water equations to show how the method is affected by various parameters such as the sampling time, sampling numbers, and the spatial resolution for the autocorrelation function. A few curious features associated with this flow model found through the analysis are further explained and discussed.
서용권,김용균,문종춘,Seo,Yong-Gwon,Kim,Yong-Gyun,Mun, Jong-Chun 대한기계학회 1997 大韓機械學會論文集B Vol.21 No.12
Numerical study on the chaotic stirring of the screw extruder model proposed has been performed. The velocity field was used in obtaining the trajectories of passive particles for studying the stirring effect of the screw extruder. Two nonlinear dynamical tools, that are Poincare sections and Lyapunov exponents, were used in analysing the stirring effect. The Poincare sections and the Lyapunov exponents show that the stirring effect is most satisfactory, when n(the number of flights in a section) is 1, for the case a (aspect ratio ; flight height divided by the spacing between flights) being O.1. It is also required to set n=3, or 5 at a= 0.2, 0.3 for a uniform stirring.
서용권 대한기계학회 1989 大韓機械學會誌 Vol.29 No.5
chaos란 "질서 있는 무질서"를 의미한다. chaos의 큰 특징은 초기조건에의 민감성이다. 역으로 말 하면, 주어진 운동은 초기조건에 민감하므로 chaotic한 운동을 한다고 말할 수 있겠다. 제2장에서 는 유동문제의 대표격인 Lorenz chaos를 살펴보고, 3장에서는 동역학 문제인 Duffing-Holmes방 정식, 4장에서는 map의 대명사인 logistic map을, 5장에서는 기타 무수히 많은 분야 중 기계공 학에 가장 가까운 것들을 골라 연구된 내용을 소개하고 그 특징들을 살펴본다. 6장과 7장에서는 chaos의 정량화를 위한 Lyapunov지수와 fractal dimension의 개념과 그 계산 방법을 다룬다. 8 장에서는 현재까지도 그 의문이 풀리지 않은, chaos학문의 큰 관심사인, 난류의 시작문제를 취 급하고, 마지막으로 9장에서는 문제점, 과제 및 앞으로의 전망을 살펴보기로 한다. 살펴보기로 한다.
서용권,문종춘 대한기계학회 1994 대한기계학회논문집 Vol.18 No.2
Study on the chaotic stirring has been performed numerically and experimentally for a shallow rectangular tank accompanying a vortex shedding. The model is composed of a rectangular tank with a vertical plate with a length half the width of the tank. The tank is subject to a horizontal sinusoidal oscillation. The chaotic stirring was analysed by Poincare sections, unstable manifolds and Lyapunov exponents. As Reynolds number is increased the stirring effect is decreased due to the growth of a regular regions near the lower surface of the tank. In the other hand decrease of Reynolds number gives a weaker vortex shedding resulting in the poorer stirring effect. It was also found that the Lyapunov exponent is the highest at the dimensionless period of 1.3-1.5, which seems to be the best condition for the efficient stirring. The experimental visualization for the deformation of materials exhibits the striation pattern similar to the unstable manifold obtained numerically.