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유신오(S. O. Ryu),박정우(J. W. Park),최병호(B. H. Choi),서이수(L. S. Seo) 한국자기학회 2000 韓國磁氣學會誌 Vol.10 No.1
In the present work, we analyze theoretically the flow of magnetic fluids in a circular pipe with longitudinal magnetic field. We used governing equations induced Shliomis and Polar theory of Eringen. Using theoretical equations and distributions for the velocity, vorticity and angular velocity as the magnetic response, it is shown that magnetic fluid flow is non-Newtonian fluid. We investigate dynamic characteristic of magnetic fluid by comparing longitudinal magnetic field with transverse magnetic field. And, the limits, influence magnetic fluid, of the intensity of the magnetic field with polar, size and magnetic effect parameters are shown.
자성유체의 Benard 유동에서 열전달특성에 관한 수치적 연구
박정우(J.W. Park),진성호(S.H. Jin),전철호(L.S. Seo),서이수(C.H. Jun),김영삼(Y.S. Kim) 한국자기학회 2003 韓國磁氣學會誌 Vol.13 No.1
This study deals with the Benard flow of magnetic fluids in a rectangular cavity. The ratio of height to length of the cavity is 1:4 and the bottom of the cavity is assumed to be a heating face while the other sides are to be cooling faces. When magnetic field was equally impressed, considering the internal rotation of the elementary ferromagnetic particle, we found the following result from the numerical analysis of the GSMAC algorithm applied to the equations for the magnetic fluid. Benard flow was controled by the intensity and the direction of magnetic fields, and a critical point was appeared when the magnetic field near H=-7000 was applied.
박정우(J. W. Park),전철호(C. H. Jun),서이수(L. S. Seo),유신오(S. O. Ryu) 한국자기학회 2002 韓國磁氣學會誌 Vol.12 No.2
Compared with Newtonial fluids, magnetic fluids have effects on magnetic force. In this study, the purpose is to research the heat transfer characteristic of magnetic fluids which have metalic and fluid characteristics as the external pipe is being cooled and internal pipe is heated. This study found the experimental results from the study of the variety of natural convection for magnetic fluids and the characteristics of the heat transfer by using numerical analysis according to the strength and direction of the magnetic fields from being imposed from the outside. Natural convection of magnetic fluids was controlled by the impressed magnetic fields, and the result of mean nusselt number was calculated. If the impressed magnetic field is in the direction of gravity or the strength of impressed magnetic field is more than -14 mT in the opposite direction, the heat transfer is more than that without the impressed magnetic field. If the strength of impressed magnetic field is less than -14 mT in the opposite direction, it is smaller than that without the impressed magnetic field. Especially, when the strength of the magnetic field is -14 mT, the heat transfer was at the minimum.
박정우(J.W.Park),박기태(G.T.Park),서이수(L.S.Seo) 대한기계학회 2003 대한기계학회 춘추학술대회 Vol.2003 No.4
In this study, to research characteristics of heat flow of magnetic fluid, it's studied about numerical and experimental method of natural convections change and characteristics of heat transfer in Concentric double pipe annuli as analysis model. In the result, natural convection of magnetic fluid is controlled by direction and strength of the impressed magnetic field. Especially, according to average Nusselt number, heat transfer is the smallest on the balancing point between body force and buoyancy.
이중원관내 자성유체의 외부자장에 대한 자연대류의 실험적 연구
박정우(J. W. Park),이준희(J. H. Lee),서이수(L. S. Seo) 한국자기학회 2001 韓國磁氣學會誌 Vol.11 No.6
Natural convection of a magnetic fluid is different from that of Newtonian fluids because magnetic body force exists in an addition to gravity and buoyancy. In this paper, natural convection of a magnetic fluids (W-40) in annular pipes was studied by experimentally. Inside wall was kept at a constant temperature (25 ℃), and outside wall was also held at a constant but lower temperature (20 ℃). The magnetic fields of various magnitude were applied up. This study has resulted in the following fact that the natural convection of a magnetic fluids was controlled by the direction and intensity of the magnetic fields.
유신오,박정우,서이수 동아대학교 생산기술연구소 1999 生産技術硏究所硏究論文集 Vol.4 No.1
In the present paper, we theoretically analyze the flow of magnetic fluids in a circular pipe with a vertical magnetic field and investigate the magnetic response by the external magnetic field. Theoretical study through the governing equation derived by Siliomis is carried out with numerical analysis by the Gauss Elimination Method. Using polar and magnetic effect parameters, theoretical equations and distributions for the velocity, vorticity, internal angular momentum and induced magnetization as the magnetic response are shown. Especially, in the region of strong magnetic field the specific property is appeared by finding a critical magnetic effect parameter for a polar effect parameter and we theorefically analyze characteristic of induces magnetization as the magnetic response.