• Title/Summary/Keyword: Lattice Boltzmann

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Direct Simulation of Flows and Flow Noise around Moving Body by FDLBM with ALE Model (ALE모델을 갖는 차분격자볼츠만법에 의한 이동물체 주위의 유동장 및 유동소음의 직접계산)

  • Kang, Ho-Keun;Michihisa, Tsutahara;Kim, Myoung-Ho;Kim, Yu-Taek;Lee, Young-Ho
    • Proceedings of the Korean Society of Marine Engineers Conference
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    • 2005.11a
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    • pp.248-249
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    • 2005
  • In this paper, flowfield and acoustic-field around moving bodies are simulated by the Arbitrary Lagrangian Eulerian (ALE) formulation in FDLBM. The effect of the ALE is checked by comparing flow about a square cylinder in ALE formulation and that in the fixed coordinates, and the results show good agreement. Matching procedure between the moving grid and fixed grid is also considered. The applied method in which the both grids are connected through buffer zone is shown to be superior to moving overlapped grid. Dipole-like emissions of sound wave from harmonically vibrating bodies in 2- and 3-dimensional cases are simulated.

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BRIEF REVIEW OF LATEST DIRECT NUMERICAL SIMULATION ON POOL AND FILM BOILING

  • Kunugi, Tomoaki
    • Nuclear Engineering and Technology
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    • v.44 no.8
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    • pp.847-854
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    • 2012
  • Despite extensive research efforts, the mechanism of the nucleate boiling phenomena is still not clear. A direct numerical simulation of the boiling phenomena is one of the promising approaches in order to clarify its heat transfer characteristics and discuss their mechanism. Therefore, many DNS procedures have been developed based on recent highly advancing computer technologies. This brief review focuses on the state of the art in direct numerical simulation of the pool boiling phenomena over the past two decades. In this review, the fundamentals of the boiling phenomena and the bubble departure and micro-layer models are briefly introduced, and then the numerical procedures for tracking or capturing interface/surface shape such as the front tracking method, level set method, volume of fluid treatments, and other methods (Lattice Boltzmann method, phase-field method and so on) are briefly reviewed.

Validation of Aero and Aero-Acoustics simulation for HAWT Model through LBM based technology

  • Senthooran, Sivapalan;Kandasamy, Satheesh;Balasubramanian, Ganapathi
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2010.05a
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    • pp.340-341
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    • 2010
  • A computational study to capture the flow around a floor mounted greenhouse shaped HAWT model was performed using the commercial software PowerFLOW 4.2b. The simulation kernel of this software is based on the numerical scheme known as the Lattice Boltzmann Method (LBM), combined with an RNG turbulence model. Simulations were performed at 60 and 140 km/h free stream air speeds. Selective results from these computational simulations are presented to show the capability of this numerical approach to predict the aerodynamics and aeroacoustics characteristics of the 3-D flow field around the HAWT model.

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Numerical Study of Particle Collection and Entrainment in Electrostatic Precipitator (집진기내 입자 포집과 비산 문제에 대한 수치적 연구)

  • Kim, Ju-Hyeon;Kweon, Soon-Cheol;Kwon, Ki-Hwan;Lee, Sang-Hwan;Lee, Ju-Hee
    • The KSFM Journal of Fluid Machinery
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    • v.15 no.1
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    • pp.27-35
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    • 2012
  • A numerical simulation for particle collection efficiency in a wire-plate electrostatic precipitator (ESP) has been performed. Method of characteristics and finite differencing method (MOC-FDM) were employed to obtain electric field and space charge density, and lattice boltzmann method (LBM) was used to predict the Electrohydrodynamic (EHD) flow according to the ion convection. Large eddy simulation (LES) was considered for turbulent flow and particle simulation was performed by discrete element method (DEM) which considered field charging, electric force, drag force and wall-collision. One way coupling from FDM to LBM was used with small and low density particle assumption. When the charged particle collided with the collecting plate, particle-wall collision was calculated for re-entertainment effect and the effect of gravity force was considered.

The capture of small variations in interior noise levels using PowerFLOW

  • Cyr, Stephane;Choi, Eui-Sung;Moron, Philippe;Senthooran, Siva
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2014.10a
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    • pp.565-568
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    • 2014
  • Hyundai Motor Company is proposing the fourth evolution of their Hyundai Simplified Model as benchmark results for the validation of CFD codes in aeroacoustics and noise transmission to the interior of a cabin. The focus of this benchmark is on variations in noise level induced by small typical geometry changes that can be found in a car development program. This article presents the noise transmission results obtained with PowerFLOW in combination with a SEA model and shows that it is possible to capture small variations in noise level with a lattice Boltzmann method based code.

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Analysis of Nano-Scale Heat Conduction in the Quantum Dot Superlattice by Ballistic Diffusive Approximation (Ballistic Diffusive Approximation에 의한 Quantum Dot Superlattice의 나노열전달 해석)

  • Kim, Won-Kap;Chung, Jae-Dong
    • Proceedings of the KSME Conference
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    • 2004.04a
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    • pp.1376-1381
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    • 2004
  • Understanding the thermal conductivity and heat transfer processes in superlattice structures is critical for the development of thermoelectric materials and optoelectronic devices based on quantum structures. $Chen^{(1)}$ developed ballistic diffusive equation(BDE) for alternatives of the Boltzmann equation that can be applied to the complex geometrical situation. In this study, a simulation code based on BDE is developed and applied to the 1-dimensional transient heat conduction across a thin film and transient 2-dimensional heat conduction across the film with heater. The obtained results are compared to the results of the $Chen^{(1)}$ and Yang and $Chen^{(1)}$. Finally, steady 2-dimensional heat conduction in the quantum dot superlattice are solved to obtain the equivalent thermal conductivity of the lattice and also compared with the experimental data from $Borca-Tasciuc^{(2)}$.

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Experimental Study on Performance of a Propulsive Nozzle with a Blower Piping System

  • Sakamoto, Masahiko
    • International Journal of Fluid Machinery and Systems
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    • v.6 no.4
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    • pp.213-221
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    • 2013
  • The characteristics of the thrust for ship propulsion equipment directly driven by air compressed by pressure fluctuation in a blower piping system are investigated. The exhaust valve is positioned upon the air ejection hole in the discharge pipe in order to induce the large-scale pressure fluctuation, and the effects of the valve on the pressure in the pipes and the thrust for the propulsive nozzle are examined. The pressure in the pipes decreases immediately after the valve is opened, and it increases just before the valve is closed. The thrust for the propulsive nozzle monotonically increases with increasing number of revolutions and depth. The interfacial wave in the nozzle appears in the frequency of approximately 4Hz, and it is important for the increase of the thrust to synchronize the opening-closing cycle for the exhaust valve with the generation frequency of the interfacial wave. The finite difference lattice Boltzmann method is helpful to investigate the characteristics of the flow in the nozzle.

Lattice Boltzmann Method를 이용한 AFM 탐침과 표면 사이에 생성되는 물 메니스커스 특성 전산 모사

  • Kim, Gi-Deok;Byeon, Gi-Sang;Kim, Hyo-Jeong;Jang, Jun-Gyeong
    • Proceeding of EDISON Challenge
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    • 2016.03a
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    • pp.131-134
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    • 2016
  • 이번 연구에서는 현재 반도체 제조 공정에 응용 가능성이 높은 DPN(Dip Pen Nanolithography)의 주요 요소인 탐침과 기판 사이의 물 메니스커스 형성에 관한 것이다. DPN의 해상도가 높을수록 더 미세한 공정을 손쉽게 수행 할 수 있기 때문에 현재 중요한 연구 과제 중 하나이다. 이번 실험에서는 기판과 탐침의 습윤도(wettability), 탐침의 모양 그리고 탐침과 기판 사이의 거리 변화에 따른 물 메니스커스 형성 정도를 실험하였다. 그 결과 탐침이 뾰족할 수록 형성이 잘 되지 않는 것으로 나왔다. 또한 좁은 계(confined system)가 기판과 탐침 사이에서만 형성되는 것이 아니라 탐침 상단에서도 형성되는 것으로 관찰되었다.

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Rheological Modeling of Nanoparticles in a Suspension with Shear Flow (전단 흐름을 갖는 서스펜션 내부 나노 입자의 유변학적 특성 연구)

  • Kim, Gu;Fukai, Jun;Hironaka, Shuji
    • Applied Chemistry for Engineering
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    • v.30 no.4
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    • pp.445-452
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    • 2019
  • Shear thickening is an intriguing phenomenon in the fields of chemical engineering and rheology because it originates from complex situations with experimental and numerical measurements. This paper presents results from the numerical modeling of the particle-fluid dynamics of a two-dimensional mixture of colloidal particles immersed in a fluid. Our results reveal the characteristic particle behavior with an application of a shear force to the upper part of the fluid domain. By combining the lattice Boltzmann and discrete element methods with the calculation of the lubrication forces when particles approach or recede from each other, this study aims to reveal the behavior of the suspension, specifically shear thickening. The results show that the calculated suspension viscosity is in good agreement with the experimental results. Results describing the particle deviation, diffusivity, concentration, and contact numbers are also demonstrated.

Understanding and predicting physical properties of rocks through pore-scale numerical simulations (공극스케일에서의 시뮬레이션을 통한 암석물성의 이해와 예측)

  • Keehm, Young-Seuk;Nur, Amos
    • 한국지구물리탐사학회:학술대회논문집
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    • 2006.06a
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    • pp.201-206
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    • 2006
  • Earth sciences is undergoing a gradual but massive shift from description of the earth and earth systems, toward process modeling, simulation, and process visualization. This shift is very challenging because the underlying physical and chemical processes are often nonlinear and coupled. In addition, we are especially challenged when the processes take place in strongly heterogeneous systems. An example is two-phase fluid flow in rocks, which is a nonlinear, coupled and time-dependent problem and occurs in complex porous media. To understand and simulate these complex processes, the knowledge of underlying pore-scale processes is essential. This paper presents a new attempt to use pore-scale simulations for understanding physical properties of rocks. A rigorous pore-scale simulator requires three important traits: reliability, efficiency, and ability to handle complex microstructures. We use the Lattice-Boltzmann (LB) method for singleand two-phase flow properties, finite-element methods (FEM) for elastic and electrical properties of rocks. These rigorous pore-scale simulators can significantly complement the physical laboratory, with several distinct advantages: (1) rigorous prediction of the physical properties, (2) interrelations among the different rock properties in a given pore geometry, and (3) simulation of dynamic problems, which describe coupled, nonlinear, transient and complex behavior of Earth systems.

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