• Title/Summary/Keyword: Body Force (體積力)

Search Result 12, Processing Time 0.026 seconds

An Observation of Unified Force Expression in The Cylindrical Magnetic Material with a Vertical Current Running Through Its Center (전류가 관통하는 원통형 자성체에 미치는 전자기력식의 통일성에 대한 고찰)

  • Choi, Hong-Soon
    • Journal of the Korean Magnetics Society
    • /
    • v.21 no.5
    • /
    • pp.174-179
    • /
    • 2011
  • Magnetic force calculation methods such as Maxwell stress, virtual work principle, equivalent magnetic charge, and equivalent magnetizing current are widely used until now. The force density is still controversial issue even though it is common sense that all of these methods have legitimate results. The surface force densities of each method are quite different with each other in the point of numerical result and final expression. In this paper, it is shown that a unified expression of body force density is derived using virtual air-gap scheme for an analytic model in which cylindrical magnetic material with a vertical current runs through its center.

Ferrofluid shape formation based on electromagnetic body force (전자기 체적력에 의한 자성유체의 자유표면 도출)

  • Choi, Hong-Soon;Kim, Young-Sun;Park, Il-Han;Kim, Kwang-Tae
    • Proceedings of the KIEE Conference
    • /
    • 2007.07a
    • /
    • pp.132-133
    • /
    • 2007
  • 자성유체의 전자기력에 의한 거동 파악을 위해 전자기 체적력에 의한 접근법을 제안한다. 정유체역학식에 수정 된 Kelvin 가진력식이 도입되며, 유체표면에서의 압력이 일정하여야 한다는 원리에서 유체 표면의 형상을 얻어낼 수 있다.

  • PDF

Precision Simulation of Drawing Processes Considering Back Pressing or Tension with Artificial Body Force Scheme (인위적 체적력 기법에 의한 후방 가압 및 인장을 고려한 인발공정의 정밀 시뮬레이션 기술)

  • Eom, J.G.;Shim, S.H.;Cho, J.M.;Kim, H.S.;Joun, M.S.
    • Transactions of Materials Processing
    • /
    • v.20 no.6
    • /
    • pp.461-467
    • /
    • 2011
  • An artificial body force method is presented to accurately simulate drawing processes in which back pressing is exerted. A rigid-plastic finite element method is applied together with a numerical scheme to eliminate the numerically incurred plastic deformation in rigid or elastic region, which significantly influences simulation results because it eventually changes reduction of area in drawing. Back tension or compression is applied by body force at the rear part of material to obtain numerically stable solution. Two typical examples are shown, a drawing process with back tension applied and a tube drawing with a fixed plug and back pressing applied.

Body Force Distribution in Permanent Magnet Motors (영구자석 전동기에서의 체적력 분포 관찰)

  • Choi, Hong-Soon;Kim, Young-Sun;Park, Il-Han
    • Proceedings of the KIEE Conference
    • /
    • 2006.07b
    • /
    • pp.659-660
    • /
    • 2006
  • 전기기기에서의 전자기력 계산은 기기의 성능뿐 아니라 기계적 변형, 진동을 예측하는 주요 파라미터이다. 지금까지는 Maxwell stress tensor법이나 자하법, 가상변위법등에 의해 전체 전자기력 또는 토크를 계산하여 왔으나, 이 방법들은 모두 분포 전자기력을 계산할 수 없었다. 본 논문에서는 기기 내부의 체적 전자기력분포를 계산하는 방법을 제시하고, 그 예로써 영구자석형 전동기의 전자기력 분포를 보여준다. 체적력의 계산은 저자에 의해 제안 된 가상공극법에 기반하여 구현할 수 있다.

  • PDF

An experimental study on resonance reduction of system with one degree of freedom by magneticfluid (자성 유체를 이용한 1자유도 계의 공진멸소에 관한 실험적 연구)

  • Chun, U. H.;Lee, B. G.;Hwang, S. S.;Lee, H. S.;Kim, J.
    • Transactions of the Korean Society of Automotive Engineers
    • /
    • v.7 no.9
    • /
    • pp.131-137
    • /
    • 1999
  • Under magnetism , as the magneticfluid is being itself magnetized, increase the apparent viscosity because of its body force and has the magnetic characteristics in response ot magnetism, the magnetic fluid is getting attention in various field. The magnetic fluid has the fluidity, which is a special characteristics of fluid and the magneticism , which is a special one of solid. Using this characteristics, this study has been proceeded to show the basic data for developing of a viscous damper with magnetism fluid as hydraulic fluid. Experimental study shows that the application of magnetic field is effective reducing the resonance characteristics of the spring-mass system.

  • PDF

Evaluation of Course Stability Performance for Tanker using CFD (CFD를 이용한 Tanker의 침로안정성 평가)

  • Hong, Chun-Beom;Yang, Hee-Jun
    • Journal of the Society of Naval Architects of Korea
    • /
    • v.45 no.5
    • /
    • pp.523-529
    • /
    • 2008
  • The course stability performance for tankers is evaluated by computational fluid dynamics. In the present work, a Reynolds averaged Navier-Stokes (RANS) code is applied to a maneuvering problem covering the pure drift and yaw motions. The purposes of this study are to evaluate the hydrodynamic force in the bare hull (AFRAMAX) in pure drift and yaw motion and to provide information about the trends in the forces and moments when the rudder angles are varied. The flow simulation is performed by FLUENT. The CFD code is examined to find the optimistic computational condition such as size of grid, turbulence model and initial condition. The hydrodynamic derivatives in drift and pure yaw motion are estimated by the numerical simulation, and then the stability levers are calculated. It is confirmed that the computations show the superiority and inferiority of course stability performance according to the hull forms. Finally, the CFD code is applied to the estimation of the rudder forces when the rudder angles are varied. The propeller effect expressed by the body force distribution is also included.

Effect of aerodynamic drag force on liquid metal convection in GTA welding (GTA 용접시 발생하는 용융금속의 유동에 미치는 공기역학적 향력의 영향)

  • 나석주;김성도
    • Transactions of the Korean Society of Mechanical Engineers
    • /
    • v.15 no.2
    • /
    • pp.575-583
    • /
    • 1991
  • The weld pool convection problem that occurs during the stationary GTA welding has been studied, considering the four driving forces for weld pool convection, i.e., the electromagnetic force, the buoyancy force, the aerodynamic drag force, and the surface tension force at the weld pool surface. In the numerical simulation, the difficulties associated with the irregular moving liquid-solid interface have been successfully overcome by adopting a Boundary-Fitted Coordinate system. In the experiments to show the validity of the numerical analysis, a deep periphery and shallow centerpentrated weld pool shape was observed from the etched specimen. It could be revealed that this type of weld pool shape could be simulated, only when some of aerodynamic drag force distributions are considered. Although slight disagreement arose, the calculated and the observed weld pool shapes were in a reasonable agreement.

Segregated finite element method by introducing a improved open boundary condition (개선된 개방경계조건을 도입한 분리유한요소법)

  • Oh, Seung-Hun;Min, Tae-Gee;Yoo, Jung-Yul
    • Proceedings of the KSME Conference
    • /
    • 2000.04b
    • /
    • pp.698-703
    • /
    • 2000
  • In a computational fluid dynamics, the imposition of open boundary condition has an important part of the accuracy but it is not easy to find the optimal boundary rendition. This difficult is introduced by making artificial boundary in unbounded domairs. Such open boundary requires us to ensure the continuity of all primitive variables because the nature is in continuum. Here we introduce a revised well-conditioned open boundary condition particularly in FEM and apply it to various problems-entrainment, body force, short domains.

  • PDF

Higher Order Axismmetric Boundary Element Analysis of Turbine Rotor Disk of the Small Turbojet Engine (고차 축대칭 경계 요소에 의한 소형 터보젯 엔진의 터빈 로우터 디스크 해석)

  • Kim, Jin-Woo
    • Journal of the Korea Institute of Military Science and Technology
    • /
    • v.1 no.1
    • /
    • pp.128-144
    • /
    • 1998
  • The BEM for linear elastic stress analysis is applied to the highly rotating axisymmetric body problem which also involves the thermoelastic effects due to steady-state thermal conduction. The axisymmetric BEM formulation is briefly summarized and an alternative approach for transforming the volume integrals associated with such body force kernels into equivalent boundary integrals is described in a way of using the concept of inner product and vector identity. A discretization scheme for higher order BE is outlined for numerical treatment of the resulting boundary integral equations, and it is consequently illustrated by determining the stress distributions of the turbine rotor disk of the small turbojet engine(ADD 500) for which a FEM stress solution has been furnished by author.

  • PDF

Analysis of Flow Around A Rigid Body on Water-Entry & Exit Problems (접수와 이수 문제에서 강체주위 유동해석)

  • Il-Ryong Park;Ho-Hwan Chun
    • Journal of the Society of Naval Architects of Korea
    • /
    • v.36 no.4
    • /
    • pp.37-47
    • /
    • 1999
  • A Finite Volume Method for the discretization of the two-dimensional incompressible Navier-Stokes equation is used to analyse water entry & exit problems in a generalized coordinate system. The free-surface deformations generated by the water entry or exit of a rigid body are simulated by the Level-Set scheme[11]. In the water entry problems for a wedged section and a flared-ship section, the calculation results of water impact force are compared with the experimental results[5] and the time varying free-surface deformations and flow characteristics of the water exit of a cylinder are investigated.

  • PDF