• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.30-33
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• 2007

DSMC method is now widely accepted CFD approach to compute and simulate the nozzle plume in rarefied regimes. In this study, using SMILE(Statistical Modeling in Low-density Environment) code which was developed in ITAM, Russia and coded using DSMC method, the internal flow of the Rothe micronozzle was simulated. Moreover, to show the validity of the SMILE code, the centerline temperatures according to the Reynold's number were compared with the ones obtained by the Rothe's experiment.

• Geophysics and Geophysical Exploration
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• v.12 no.4
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• pp.281-288
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• 2009

Using analytical method, intrinsic absorption and scattering attenuation was lately separated from total quality factor $(Q^{-1}_t)$ on the seismic data of Korean Peninsula. However, we should use numerical method rather than the analytical method to consider depth dependent structure of scattering. The direct simulation Monte Carlo (DSMC) method, as a kind of the numerical method, is good option due to its extended availability from 1 to 3-dimensional model; but there is few study to use it. In this paper, we introduced the analytical method and the DSMC method, and compared the results of the two analysis applied to the isotropic scattering model. While the scattering attenuation coefficients $(\eta_s)$ are identical, the intrinsic absorption coefficients $(\eta_i)$ for the analytical method are larger than those for DSMC method and have large errors. In addition, the $(Q^{-1}_t)$ by the previous studies show closer to DSMC method than analytical method.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.769-771
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• 2011

The satellite payloaded on the 2nd stage of KSLV-I is planned to perform CCAM(Contamination and Collision Avoidance Maneuver) not to collide with KM(Kick Motor). At the moment, the satellite should pass through low density environment not to be contaminated by KM plume due to residual thrust. Therefore, it is necessary to predict the flow field of KM plume by residual thrust. In this paper, DSMC (Direct Simulation Monte-Carlo) method, which is widely accepted to simulate in rarefied regime, is used to compute the density field of KM plume by residual thrust and the result of DSMC simulation was compared with that of FLUENT to validate it.

• Proceedings of the KSME Conference
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• 2005.11a
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• pp.62.1-62.1
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• 2005

• 한국전산유체공학회:학술대회논문집
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• 1995.10a
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• pp.235-240
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• 1995

The paper describes hypersonic rarefied flow of helium and nitrogen over a flat plate by the direct simulation Monte Carlo (DSMC) method. The effect of incomplete accommodation and plate thickness are analyzed and the computational results are compared with wind tunnel test data. Also computational aspects of the method are outlined.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.532-532
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• 2013

세계의 반도체, 의료, 금속, 섬유 등의 분야에서 기술이 고도화됨에 따라서 나노 입자, High quality 박막 등에 대한 수요는 커져가고 있다. 이를 제조하기 위한 공정은 극 저압 상태에서 이루어진다. 따라서 극 저압 기체 흐름에 대한 이해는 필수적이다. 하지만 일반적으로 수 mTorr 이하의 압력에서는 유체 시뮬레이션으로 해석하는 것이 불가능하다. 그러므로 우리는 DSMC 방법을 이용하여 극 저압 CCP 챔버 내의 기체의 흐름을 해석하고 특성을 살펴보았다.

• Journal of the Korean Society of Propulsion Engineers
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• v.18 no.6
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• pp.27-33
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• 2014

2nd stage of KSLV-I, NaRo-Ho, performs CCAM not to collide with Naro Science Satellite. At that moment, the satellite should pass through the Plume Density area which was generated by KSLV-I KM residual thrust. Therefore, it is necessary to predict Plume Density field of KM residual thrust and guarantee the safety of the trajectory of payload. In this paper, DSMC method was used to simulate Plume Density by KM residual thrust and the simulation showed that the trajectory of Naro Science Satellite was safe.

• Journal of the Korean Society of Propulsion Engineers
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• v.25 no.4
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• pp.1-11
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• 2021

To develop technologies for the stable operation of electric propulsion systems, the exhaust plume behavior of electric thrusters was studied using PIC-DSMC(particle-in-cell and direct simulation Monte Carlo). For the numerical analysis, the Simple Electron Fluid Model using Boltzmann relation was employed, and the charge and momentum exchanges due to atom-ion collisions were considered. The results of this study agreed with the plasma potentials measured experimentally. Near the thruster exit, active collisions among particles and charge exchanges created slow ions and fast atoms, which were expected to significantly affect the trajectory and velocity of the thruster exhaust plume.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.08a
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• pp.90-90
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• 2011

배기속도 2,500 L/s, 최고진공도 10-10 mbar를 구현할 대용량 복합 분자펌프 설계를 위한 2차원과 3차원 형상을 대상으로 실시하였다. 진공도가 10-5 mbar 이상이 되는 고진공도에서는 Knudsen 수가 102~107에 이르러 분자간 충돌을 거의 무시할 수 있게 되며, 이때의 유체해석 방법으로서는 통상 희박기체 해석법으로 많이 쓰이는 Direct Simulation Monte Carlo (DSMC) 방법보다, 충돌이 없는 분자의 자유운동을 모사하는 Monte Carlo 방법이 더 적합하게 된다. 본 연구에서는 다단계 rotor와 stator로 구성되는 복합분자 내 유동장에 Monte Carlo 해석법과 DSMC 방법을 모두 적용하여 유동해석을 실시하였다. 먼저 2차원 모델에 대한 해석을 실시하여 분자펌프의 성능에 중요한 영향을 미치는 설계변수로 날개각과 날개간격이 현저함을 확인하였으며, 이 설계변수들이 펌프의 주요성능 지표인 최대펌핑효율과 최대압축비에 미치는 영향을 다양한 3차원 유동해석을 통해 도출하였다. 유동해석 결과, 기체분자와 rotor 날개사이의 충돌 확률을 높이는 방안이 대체적으로 펌프의 성능을 향상시키는데 도움이 되는 것으로 나타났다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.27 no.12
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• pp.1667-1672
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• 2003

In contrast to the high demand for MEMS devices, microflow analysis is not feasible even for single-phase flow with conventional Navier-Stokes equation because of non-continuum effect when characteristic dimension is comparable with local mean free path. DSMC is one of particle based DNS(Direct Numerical Simulation) methods that uses no continuum assumption. In this paper, gas flow in microchannel is studied using DSMC. Interfacial shear and flow characteristics are observed and compared with the results of gas flow that is in contact with liquid case and solid wall case. The simulation is limited to the case of equilibrium steady state and evaporation/condensation coefficient is assumed to be the same and unity. System temperature remains constant and the interfacial shear appears to be small compared to the result with solid wall. This is because particles evaporated and reflected from the liquid surface form high density layer near the interface with liquid flow.