• Title/Summary/Keyword: DSMC (Direct simulation monte carlo)

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Simulation of Molecular Flows Inside a Guide Block in the OLED Deposition Process (OLED 박막 증착공정에서 유도로 내부의 분자유동 해석)

  • Sung, Jae-Yong;Lee, Eung-Ki
    • Transactions of the Korean Society of Machine Tool Engineers
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    • v.17 no.2
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    • pp.45-50
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    • 2008
  • Molecular flows inside a guide block in the OLED(organic luminescent emitting device) deposition process have been simulated using DSMC(direct simulation Monte Carlo) method. Because the organic materials are evaporated under vacuum, molecules flow at a high Knudsen number of the free molecular regime, where the continuum mechanics is not valid. A guide block is designed as a part of the linear cell source to transport the evaporated materials to a deposition chamber, When solving the flows, the inlet boundary condition is proved to affect significantly the whole flow pattern. Thus, it is proposed that the pressure should be specified at the inlet. From the analysis of the density distributions at the nozzle exit of the guide block, it is shown that the longer nozzle can emit molecules more straightly. Finally, a nondimensionalized mass flow profile is obtained by numerical experiments, where various nozzle widths and inlet pressures are tested.

Three Dimensional Direct Monte Carlo Simulation on OLED Evaporation Process (유기EL 증착 공정에 대한 3차원 Monte Carlo 해석)

  • Lee, Eung-Ki
    • Journal of the Semiconductor & Display Technology
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    • v.8 no.4
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    • pp.37-42
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    • 2009
  • The performance of an OLED(organic luminescent emitting device) fabrication system strongly depends on the design of the evaporation cell-source. Trends in display sizes have hauled the enlargement of mother glass substrates. The enlargement of substrates requires the improvement and the enlargement of the effusion cell-source for OLED evaporation process. The deposited layers should be as uniform as possible, and therefore it is important to know the effusion profile of the molecules emitted from the cell-source. Conventional 2D DSMC algorithm cannot be used for simulating the new concept cell-source design, such as a linear source. This work concerns the development of 3D DSMC (direct simulation Monte Carlo) analysis for simulating the behavior of the evaporation cell-sources. In this paper, the 3D DSMC algorithm was developed and the film thickness profiles were obtained by the numerical analysis.

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The Study on the Two-Phase Flow in the Microchannel Using DSMC(Direct Simulation Monte Carlo) Method (DSMC(Direct Simulation Monte Carlo)방법을 이용한 마이크로관 내에서의 2 상유동에 관한 연구)

  • Lee, Jin-Ho;Ryu, Dong-Hun;Lee, Tae-Hong
    • 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.

Direct Simulation of Compression and Pumping Characteristics for a Gaede-Type Drag Pump (분자드래그펌프의 압축 밀 배기특성 해석)

  • 이영규;이진원
    • Journal of the Korean Vacuum Society
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    • v.4 no.4
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    • pp.343-349
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    • 1995
  • 게데형 분자드래그펌프의 배기특성을 강구(hard sphere)분자모델과 NTC(No Time Counter)충돌 scheme을 이용한 직접모사 법의 하나인 DSMC(direct simulation Monte Carlo)방법을 이용하여 해석하였다. 해석에 사용된 모델은 높이가 일정하고, 길이가 높이의 1~3000배 사이인 이차원 채널이다. 자유분자영역으로부터 연속체 영역까지의 영역에서 최대압축비와 배기속도를 계산하였다. 계산결과 기존의 최대압축비 이론 결과는 채널내의 압력변화가 클 때는 큰 오차를 유발하는 것을 알 수 있었고, 유동방향의 기체분자의 통과확률은 채널 길이와 출구압력에 관계없이 거의 일정한 값을 갖는다는 것을 발견하였다.

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Numerical Analysis on Thermal Transpiration Flows for a Micro Pump (열천이 현상을 이용한 마이크로 펌프내의 희박기체유동 해석)

  • Heo, Joong-Sik;Lee, Jong-Chul;Hwang, Young-Kyu;Kim, Youn-J.
    • The KSFM Journal of Fluid Machinery
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    • v.10 no.5
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    • pp.27-33
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    • 2007
  • Rarefied gas flows through two-dimensional micro channels are studied numerically for the performance optimization of a nanomembrane-based Knudsen compressor. The effects of the wall temperature distributions on the thermal transpiration flow patterns are examined. The flow has a pumping effect, and the mass flow rates through the channel are calculated. The results show that a steady one-way flow is induced for a wide range of the Knudsen number. The DSMC(direct simulation Monte Carlo) method with VHS(variable hard sphere) model and NTC(no time counter) techniques has been applied in this work to obtain numerical solutions. A critical element that drives Knudsen compressor Is the thermal transpiration membrane. The membranes are based on aerosol or machined aerogel. The aerogel is modeled as a single micro flow channel.

DSMC Simulation of Prediction of Organic Material Viscosity (DSMC 해석을 통한 유기 재료의 점성도 예측)

  • Jun, Sung Hoon;Lee, Eung Ki
    • Journal of the Semiconductor & Display Technology
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    • v.11 no.1
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    • pp.49-54
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    • 2012
  • There have been plenty of difficulties because properties of Alq3 are unable to acquire in a process of manufacture of OLED. In this paper it will predict a viscosity of Alq3 through DSMC technique and suggest the way regarding a study to estimate properties of material through the computer simulation. There could generate errors of a simulation process in a vacuum deposition process since the properties of material that is used in a high-degree vacuum environment are not secured. Therefore, we would like to propose the new methods that can not only predict properties of a molecular unit but also raise an accuracy of simulation process by forecasting properties of Alq3.

Numerical Analysis on Thermal Transpiration Flows for a Micro Pump (열천이 현상을 이용한 마이크로 펌프내의 희박기체유동 해석)

  • Heo, Joong-Sik;Lee, Jong-Chul;Hwang, Young-Kyu;Kim, Youn-J.
    • 유체기계공업학회:학술대회논문집
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    • pp.493-496
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    • 2006
  • Rarefied gas flows through two-dimensional micro channels are studied numerically for the performance optimization of a nanomembrane-based Knudsen compressor. The effects of the wall temperature distributions on the thermal transpiration flow patterns are examined. The flow has a pumping effect, and the mass flow rates through the channel are calculated. The results show that a steady one-way flow is induced for a wide range of the Knudsen number. The DSMC(direct simulation Monte Carlo) method with VHS(variable hard sphere) model and NTC(no time counter) techniques has been applied in this work to obtain numerical solutions.

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Studies on Normal Shock Waves by Using DSMC (직접모사법을 이용한 수직충격파에 관한 연구)

  • Lee D. D.;Park H. K.;Park C. K.
    • 한국전산유체공학회:학술대회논문집
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    • pp.241-245
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    • 1995
  • This paper presents the studies on the variation of shape and thickness of a normal shock wave with Mach number and density by using the most useful numerical technique in rarefied gas regime, DSMC(Direct Simulation Monte Carlo). Calculations are peformed for the three different Mach numbers and for one Mach number with different densities. From the obtained results, we find that the shock thickness is decreasing with increasing Mach number, and there are much variations in thickness and shape with decreasing density. Also, there is a noticeable overshoot of the translational temperature near the shock center in the case of a large Mach number.

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A Numerical Analysis of Rarefied Flow of Cylinder Using FDDO (FDDO를 이용한 실린더를 지나는 희박기체의 해석)

  • Ahn M. Y.;Chang K. S.
    • 한국전산유체공학회:학술대회논문집
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    • pp.138-144
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    • 1998
  • The BGK equation, which is the kinetic model equation of Boltzmann equation, is solved using FDDO(finite difference with the discrete-ordinate method) to compute the rarefied flow of monatomic gas. Using reduced velocity distribution and discrete ordinate method, the scalar equation is transformed into a system of hyperbolic equations. High resolution ENO(Essentially Non-Oscillatory) scheme based on Harten-Yee's MFA(Modified Flux Approach) method with Strang-type explicit time integration is applied to solve the system equations. The calculated results are well compared with the experimental density field of NACA0012 airfoil, validating the developed computer code. Next. the computed results of circular cylinder flow for various Knudsen numbers are compared with the DSMC(Direct Simulation Monte Carlo) results by Vogenitz et al. The present scheme is found to be useful and efficient far the analysis of two-dimensional rarefied gas flows, especially in the transitional flow regime, when compared with the DSMC method.

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DSMC Simulation of a Point Cell-source for OLED Deposition Process (유기 EL 성막 공정을 위한 점 증발원의 DSMC 시뮬레이션)

  • Jun, Sung-Hoon;Lee, Eung-Ki
    • Journal of the Semiconductor & Display Technology
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    • v.9 no.3
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    • pp.11-16
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    • 2010
  • The performance of an OLED fabrication system strongly depends on the design of the evaporation cell-source. Therefore, necessity of the preceding study for cell source development of new concept is becoming increase. A development plan to substitute for experiment is applied as use simulation. In this study interpret behavior of a particle through DSMC techniques, and in this paper presenting a form to make so as to have better performance of the pointtype cell source which had a nozzle.