• Title/Summary/Keyword: Single Particle

Search Result 883, Processing Time 0.032 seconds

Two Dimensional MOSFET Simulator using Mixed Particle Monte Carlo Method (Mixed Particle Monte Carlo 방법을 이용한 2차원 MOSFET 시뮬레이터)

  • 진교영;박영준;민홍식
    • Journal of the Korean Institute of Telematics and Electronics A
    • /
    • v.31A no.5
    • /
    • pp.134-148
    • /
    • 1994
  • A full two-dimensional MOSFET simulator utilizing the Mixed Particle Monte Carlo method is introduced. Particle simulation for both electrons and holes are self-consistently coupled with Poisson 's equation. To demonstrate the performance of the simulator, steady state and transient state solutions of the terminal characteristics and the internal physical quantities are obtained for 0.25$\mu$m MOSFETs with three different structures` conventional single drain, LDD and GOLD MOSFET structures.

  • PDF

Fluid Particle Dispersion in a Turbulent Channel Flow (난류 채널 유동에서의 유체 입자 분산)

  • Choi Jung-Il;Lee Changhoon
    • Proceedings of the KSME Conference
    • /
    • 2002.08a
    • /
    • pp.803-806
    • /
    • 2002
  • The dispersion of Lagrangian fluid particles in a turbulent channel flow is studied by a direct numerical simulation. Four points Hermite interpolation in the homogeneous direction and Chebyshev polynomials in the inhomogeneous direction is adopted by assesing the acceleration of fluid particles. In order to characterize the inhomogeneous Lagrangian statistics, accurate single particle Lagrangian statistics are obtained along the wall normal direction. Integral time scales of Lagrangian velocity can be normalized by Eulerian mean shear stresses.

  • PDF

Chemical Transformation of Individual Asian Dust Particles Estimated by the Novel Double Detector System of Micro-PIXE

  • Ma, Chang-Jin
    • Asian Journal of Atmospheric Environment
    • /
    • v.4 no.2
    • /
    • pp.106-114
    • /
    • 2010
  • By the application of novel double detector system of micro-PIXE that can detect light elements (Z<14), we made an attempt to provide a thorough discussion on the aging processes of Asian dust (hereafter called "AD") particle by reaction with sea-slat. The elemental spectra and maps obtained from the microbeam radiation of micro-PIXE to individual AD particles were useful for fractionating AD particles into both internally and externally mixed particles. A spatial distribution of elements in a minute domain of single particle obtained by scanning the microbeam irradiation enabled us not only to estimate the chemical mixing state of individual AD particles but also to presume their aging processes in both ambient air and cloud. By calculating the normalized micro-PIXE net count of elements, it was possible to classify individual AD particles into three distinct groups (i.e., (1) Aging type 1: AD particle coated by the gaseous Cl evaporated by the reaction between artificial acids and sea salt; (2) Aging type 2: AD particle mixed with sea salt but no additional reaction with artificial acids; and (3) Non-aged type) A relatively high transformation rate (63.3-75.9%) was shown in large particles (greater than $5.1\;{\mu}m$ in diameter).

Development of a Particle Bed Heat Exchanger(I) -An Experimental Study on Heat Transfer Characteristics of Fluidized Bed Heat Exchanger with Double Pipe (Counterflow) (입자층(粒子層)을 이용(利用)한 열교환기(熱交換器) 개발(開發)에 관(關)한 연구(硏究)(I) - 유동층형(流動層形) 이중관식(二重管式) 열교환기(熱交換器)의 전열특성(傳熱特性)에 대한 실험적(實驗的) 연구(硏究) (대향류식(對向流式)))

  • Lim, J.G.;Yoo, J.O.;Yang, H.J.;Seo, J.Y.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.2 no.2
    • /
    • pp.119-126
    • /
    • 1990
  • In this study, the overall heat transfer coefficients are calculated on fluidized bed double pipe heat exchanger and single phase double pipe heat exchanger at the same condition. The effect of the particle size, its material, fluidizing velocity and static bed height on overall heat transfer coefficient has been investigated. The main conclusions obtained from the experiment are as follows. 1. The overall heat transfer coefficient of the fluidized bed heat exchanger is higher than that of single phase forced convective heat exchanger (maximum 2.3 times) 2. The value of the overall heat transfer coefficient increase with an increase in static bed height and decrease with an increase in particle size. 3. For the same particle size, the particle of low density can obtain higher overall heat transfer coefficient than that of high density.

  • PDF

Collection Characteristics of a MOUDI Cascade Impactor for Coarse Particles (다단 임팩터(MOUDI)의 조대 입자 채취 특성)

  • 배귀남;지준호;문길주
    • Journal of Korean Society for Atmospheric Environment
    • /
    • v.15 no.6
    • /
    • pp.799-804
    • /
    • 1999
  • Particle collection characteristics of the MOUDI cascade impactor has been studied for coarse particles in the range of 2 to 20$mu extrm{m}$ in aerodynamic diameter. A vibrating orifice aerosol generator was empolyed to generate monodisperse test aerosols. The oleic acid and sodium chloride(NaCl) particles were used as test aerosols. Aluminum foil and Teflon filter were selected as impaction media. The sampling flow rate was changed from 25 to 35L/min. Particle collection efficiency for single stage was examined for liquid particles. The stage response was obtained experimentally for the cascade impactor composed of three stages and a backup filter. The results showed that most of particle collection efficiencies measured in this work are similar to the efficiency curves obtained by Marple et al.(1991). For particles less than cut-off size of the stage, the collection efficiencies of solid particles are similar to those of loquid particles. However, the collection efficiency of solid particles decreases with mereasing particle diameter for the particles greater than the actual cut-off size of the impactor. The particle collection efficiency increases with increasing sampling flow rate at the same particel size. However, the collection efficiency curves seem not to be greatly shifted with the flow rate. The stage responses obtained by direct measurements in this work are in good agreement with those derived from the collection efficiency curves for single stage.

  • PDF

Parametric Studies on the Sensitivity of Single Isolated Aluminum Particle Combustion Modeling (알루미늄 입자 연소 지배인자의 민감도 해석)

  • Lee, Sang-Hyup;Ko, Tae-Ho;Yang, Hee-Sung;Yoon, Woong-Sup
    • Proceedings of the Korean Society of Propulsion Engineers Conference
    • /
    • 2010.11a
    • /
    • pp.321-327
    • /
    • 2010
  • A simplified analytical modeling for micro-sized single metal particle combustion in air was conducted in the present study. The metal particle combustion consists of two distinct reaction regimes, ignition and quasi-steady burning, and the thermo-fluidic phenomena in each stage are formulated by virtue of the conservation and transport equations. Reliability of the model is shown by rigorous validation of the method with emphasis laid on the characterizing the commanding parameters. Effects of Initial particle size, initial oxide film thickness, convection, ambient pressure and temperature are examined and addressed with validation.

  • PDF

Numerical simulation on LMR molten-core centralized sloshing benchmark experiment using multi-phase smoothed particle hydrodynamics

  • Jo, Young Beom;Park, So-Hyun;Park, Juryong;Kim, Eung Soo
    • Nuclear Engineering and Technology
    • /
    • v.53 no.3
    • /
    • pp.752-762
    • /
    • 2021
  • The Smoothed Particle Hydrodynamics is one of the most widely used mesh-free numerical method for thermo-fluid dynamics. Due to its Lagrangian nature and simplicity, it is recently gaining popularity in simulating complex physics with large deformations. In this study, the 3D single/two-phase numerical simulations are performed on the Liquid Metal Reactor (LMR) centralized sloshing benchmark experiment using the SPH parallelized using a GPU. In order to capture multi-phase flows with a large density ratio more effectively, the original SPH density and continuity equations are re-formulated in terms of the normalized-density. Based upon this approach, maximum sloshing height and arrival time in various experimental cases are calculated by using both single-phase and multi-phase SPH framework and the results are compared with the benchmark results. Overall, the results of SPH simulations show excellent agreement with all the benchmark experiments both in qualitative and quantitative manners. According to the sensitivity study of the particle-size, the prediction accuracy is gradually increasing with decreasing the particle-size leading to a higher resolution. In addition, it is found that the multi-phase SPH model considering both liquid and air provides a better prediction on the experimental results and the reality.

A Study on the Interaction between Particles and Surrounding Fluid (입자와 주위유체와의 상호작용에 관한 연구)

  • ;T.Kurihara;H. Monji;G. Matsui
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.14 no.2
    • /
    • pp.108-115
    • /
    • 2002
  • The fundamental mechanism of a dispersed two-phase flow was investigated. Experiments were carried out to understand how the particles behaves under the influence of the particle size, shape, metamorphoses (bubble) and buoyancy of a single particle which is ascending from the standstill water. Two CCD cameras were employed for image processing of the behavior of the particles and the surrounding flow, which was interpreted with the technique of correlation PIV (Particle Image Velocimetry) and PTV (Particle Tracking Veloci- metry), respectively The experimental results showed that the large density difference bet- ween a particle and water caused high relative velocity and induced zigzag motion of the particle. Furthermore, the turbulence intensity of a bubble was about twice the case of the spherical solid particle of similar diameter.

Optimum shape and process design of single rotor equipment for its mixing performance using finite volume method

  • Kim, Nak-Soo;Lee, Jae-Yeol
    • Korea-Australia Rheology Journal
    • /
    • v.21 no.4
    • /
    • pp.289-297
    • /
    • 2009
  • We numerically analyzed flow characteristics of the polymer melt in the screw equipment using a proper modeling and investigated design parameters which have influence on the mixing performance as the capability of the screw equipment. We considered the non-Newtonian and non-isothermal flow in a single rotor equipment to investigate the mixing performance with respect to screw dimensions as shape parameter of the single rotor equipment and screw speed as process parameter. We used Bird-Carreau-Yasuda model as a viscous model of the polymer melt and the particle tracking method to investigate the mixing performance in the screw equipment and considered four mixing performance indexes: residence time distribution, deformation rate, total strain and particle standard deviation as a new mixing performance index. We compared these indexes to determine design parameters and object function. On basis of the analysis results, we carried out the optimal design by using the response surface method and design of experiments. In conclusion, the differences of results between the optimal value and numerical analysis are about 5.0%.