• 대한기계학회논문집B
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• 제30권8호
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• pp.806-817
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• 2006

The motion of a small rigid particle in the shear flow near a stationary flat wall is investigated in the context of Stokes flow. The lift force proposed by Saffman and later modified by Mclaughlin and Mei is considered in the prediction of the particle motion far away from the wall. Later, the expression of the lift force is modified to take into account the effect of wall. In the analysis, gravity, lift and drag acting on a small rigid particle near the wall are taken into account. Both analytical and numerical results for the terminal velocities, distances from the wall and trajectories of the particle are presented. In addition, we extended the present analysis to turbulent near-wall flow in the vicinity of the wall.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1903-1908
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• 2003

The motion of a small, heavy rigid particle in the shear flow on a stationary wall is investigated in the context of Stokes flow. The lift force proposed by Saffman(1965) and later modified by Mclaughlin(1991) and Mei(1992) is considered in the prediction of the particle motion far away from the wall. Later, the expression of the lift force is modified to take into account the effect of wall(Cherukat and Mclaughlin, 1994). In the analysis the gravity and buoyancy effect are also taken into account. An analytical and numerical results for the terminal velocities and trajectories of the particle after the enough lapse of time are presented.

• 대한기계학회논문집B
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• 제24권3호
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• pp.477-484
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• 2000

Microcontamination caused by particle deposition on the head disk interface threatens the reliability of hard disk drive. Design of slider rail to control contamination becomes an important issue in magnetic recording. In this paper, how particles adhere to the slider and the disk is examined. To investigate accumulation mechanism of the particles, trajectory of the particles in a slider/disk interface is simulated with considering various forces including drag force, gravitational force, Saffman lift force, and electrostatic force. It is found that the charged particles can easily adhere to the slider or disk surface, if an electric field exists between the slider and the disk. It is supposed that the vertical motion of the particles should be related with not only Saffman force but also electrostatic force.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회B
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• pp.2554-2557
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• 2008

Effect of a particle's spin is investigated numerically by considering the effect of lift occurring due to difference of rotations of a particle and of fluid such as the Saffman lift and Magnus force. These lift forces have been neglected in many previous works on particle-laden turbulence. The trajectory of particles can be changed by the lift forces, resulting in significant modification of the stochastic characteristics of heavy particles. Probability density functions and autocorrelations are examined of velocity, acceleration of solid particle and acceleration of fluid at the position of solid particle. Changes in velocity statistics are negligible but statistics related with acceleration are a little bit changed by particle's rotation. When a laden particle encounters with coherent structures during the motion, the particle's rotation might significantly affects the motion due to intermittently large fluid acceleration near coherent structures.

• 대한기계학회논문집B
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• 제34권7호
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• pp.665-670
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• 2010

등방성 난류에서 부유된 무거운 입자의 운동에서, 입자의 회전이 고려되었을 때 입자의 분산 특성에 나타난 변화를 살펴보았다. 입자의 회전을 고려함으로 인해 추가로 고려되는 양력은 그 크기가 작은 것으로 알려져 있고, 따라서 많은 연구에서 회전에 의한 효과는 무시되었다. 본 연구에서는 라그랑지안 기법으로 추적한 입자의 궤적에 미치는 양력의 크기를 속도와 가속도의 자기상관함수 및 확률밀도함수를 통해 정량적으로 살펴보았다. 속도 통계량에서는 양력에 의한 효과가 무시할 만 했으나, 가속도와 관련된 통계는 양력에 의한 영향이 있는 것으로 확인되었다. 난류의 가속도는 간헐성을 띄며, 간헐적인 특성은 난류 구조와 관련이 있다는 것이 알려져 있다. 따라서 입자에 작용하는 양력과 난류구조에 연관성이 있다는 유추가 가능하다.