• Title/Summary/Keyword: Eulerian-Lagrangian Model

Search Result 136, Processing Time 0.022 seconds

Structure of Particle Clusters Formed in Gas-Solid flows

  • Tanaka, Toshitsugu;Ito, Akihito;Tsuji, Takuya
    • 한국전산유체공학회:학술대회논문집
    • /
    • 2006.10a
    • /
    • pp.26-27
    • /
    • 2006
  • Characteristics of spatial structure of particle clusters are investigated by using the flow field data obtained from three-dimensional numerical simulations. Eulerian/Lagrangian approach with two-way coupling is applied and individual particle-particle collisions are taken into account by using the hard-sphere model. More than 16 million particles are traced in the maximum case. The results show that the cluster is consisted from the multiple-spatial scale components while the low wave-number, hence the large-scale structure, is dominant. Three-dimensional structure reconstructed from the low-pass filtered data enables us to investigate the essential dynamics of particle clusters in detail.

  • PDF

The Spectrally Accurate Method Applied to Wave-Current Interaction as a Freak Wave Generation Mechanism

  • Sung, Hong-Gun;Hong, Key-Yong;Kyoung, Jo-Hyun;Hong, Sa-Young
    • Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
    • /
    • 2006.11a
    • /
    • pp.113-120
    • /
    • 2006
  • In this paper, generation mechanisms of ocean freak waves are briefly introduced in the context of wave-current interaction phenomena. As an accurate and efficient numerical tool, the spectral element method is presented with general features and specific treatment for the wave-current interaction problem. The present model of the fluid motion is based on the Navier-Stokes equations incorporating a velocity-pressure formulation. In order to deal with the free surface motion, an Arbitrary Lagrangian-Eulerian (ALE) description is adopted. As an intermediate stage of development, solution procedure and characteristic aspects of the present modeling and numerical method features are addressed in detail, and numerical results for wave-current interaction is left as further study.

  • PDF

Evaluation of sloshing Resistance Performance of LNG Carrier Insulation System by Fluid-Structure Interaction Analysis (유체-구조 연성 해석을 이용한 LNG 운반선 방열시스템의 내슬로싱 성능 평가)

  • Lee, Chi-Seung;Kim, Joo-Hyun;Kim, Wha-Soo;Noh, Byeong-Jae;Kim, Myung-Hyun;Lee, Jae-Myung
    • Proceedings of the Computational Structural Engineering Institute Conference
    • /
    • 2011.04a
    • /
    • pp.557-560
    • /
    • 2011
  • In the present paper, the sloshing resistance performance of an LNG carrier insulation system is evaluated by fluid-structure interaction (FSI) analysis. For this analysis, the arbitrary Lagrangian Eulerian (ALE) method is adopted to accurately calculate the structural behavior induced by internal LNG motion of a KC-1 type LNG carrier cargo tank. In addition, the global-local analysis method is introduced to reduce computational time and cost. The global model is built from shell elements to reduce the sloshing analysis time. The proposed novel analysis techniques can potentially be used to evaluate the structural integrity of LNG carrier insulation systems.

  • PDF

Numerical evaluation of hypothetical core disruptive accident in full-scale model of sodium-cooled fast reactor

  • Guo, Zhihong;Chen, Xiaodong;Hu, Guoqing
    • Nuclear Engineering and Technology
    • /
    • v.54 no.6
    • /
    • pp.2120-2134
    • /
    • 2022
  • A hypothetical core destructive accident (HCDA) has received widespread attention as one of the most serious accidents in sodium-cooled fast reactors. This study combined recent advantages in numerical methods to realize realistic modeling of the complex fluid-structure interactions during HCDAs in a full-scale sodium-cooled fast reactor. The multi-material arbitrary Lagrangian-Eulerian method is used to describe the fluid-structure interactions inside the container. Both the structural deformations and plug rises occurring during HCDAs are evaluated. Two levels of expansion energy are considered with two different reactor models. The simulation results show that the container remains intact during an accident with small deformations. The plug on the top of the container rises to an acceptable level after the sealing between the it and its support is destroyed. The methodology established in this study provides a reliable approach for evaluating the safety feature of a container design.

Numerical Analysis of Wave-Current Interaction Phenomenon Using the Spectral Element Method (스펙트랄요소법(SEM)을 이용한 파랑-조류 상호작용 현상 수치해석 연구)

  • Sung, Hong-Gun;Hong, Key-Yong;Kyung, Jo-Hyun;Hong, Sa-Young
    • Proceedings of the Korean Institute of Navigation and Port Research Conference
    • /
    • v.1
    • /
    • pp.181-186
    • /
    • 2006
  • In this paper, generation mechanisms of ocean freak waves are briefly introduced in the context of wave-current interaction phenomena. The present model of the fluid motion is based on the Navier-Stokes equations incorporating velocity-pressure formulation because of need to model the nonlinear wave interaction with spatially non-uniform current field. In order to deal with the free surface motion, an Arbitrary Lagrangian-Eulerian (ALE) description is adopted. As an accurate and efficient numerical tool, the spectral element method is presented with general features and specific treatment for the wave-current interaction problem. As an intermediate stage of development, solution procedure and characteristics aspects of the present modeling and numerical method are addressed in detail, and preliminary numerical results prove its accuracy and convergence.

  • PDF

Analysis of Unsteady Cavitating Flows in Fuel Injection Nozzle of Piezo-driven Injector by Eulerian-Lagrangian Multi-phase Method (Eulerian-Lagrangian 다상 유동해석법에 의한 피에조 인젝터의 노즐 내부 비정상 캐비테이션 유동해석)

  • Lee, Jin-Wook;Min, Kyung-Duk;Kang, Kern-Yong;Gavaises, M.;Arcoumanis, C.
    • Journal of ILASS-Korea
    • /
    • v.9 no.4
    • /
    • pp.38-45
    • /
    • 2004
  • This study describes the analysis results of unsteady cavitating flows behavior inside nozzle of the prototype piezo-driven injector. This piezo-driven injector has been recognised as one of the next generation diesel injector due to a higher driven efficiency than the conventional solenoid-driven injector. The three dimensional geometry model along the central cross-section regarding of one injection hole has been used to simulate the cavitating flows for injection time by at fully transient simulation with cavitation model. The cavitation model incorporates many of the fundamental physical processes assumed to take place in cavitating flows. The simulations performed were both fully transient and 'pseudo' steady state, even if under steady state boundary conditions. We could analyze the effect the pressure drop to the sudden acceleration of fuel, which is due to the fastest response of needle, on the degree of cavitation existed in piezo-driven injector nozzle

  • PDF

Development and Application of the Backward-tracking Model Analyzer to Track Physical and Chemical Processes of Air Parcels during the Transport (대기오염물질의 이동경로상 물리화학적 변화 추적을 위한 Backward-tracking Model Analyzer 방법론 마련)

  • Bae, Minah;Kim, Hyun Cheol;Kim, Byeong-Uk;Kim, Soontae
    • Journal of Korean Society for Atmospheric Environment
    • /
    • v.33 no.3
    • /
    • pp.217-232
    • /
    • 2017
  • An Eulerian-Lagrangian hybrid modeling system to analyze physical and chemical processes during the transport of air parcels was developed. The Backward-tracking Model Analyzer (BMA) was designed to take advantages of both Eulerian and Lagrangian modeling approaches. Simulated trajectories from the National Oceanic and Atmospheric Administration HYSPLIT model were combined with the US Environmental Protection Agency Community Multi-scale Air Quality (CMAQ)-simulated concentrations and additional diagnostic analyses. In this study, we first introduced a generalized methodology to seamlessly match polylines (HYSPLIT) and threedimensional polygons (CMAQ), which enables mass-conservative analyses of physio-chemical processes of transporting air parcels. Two applications of the BMA were conducted: (1) a long-range transport case of pollutant plume across the Yellow Sea using CMAQ Integrated Process Rate analyses, and (2) a domestic circulation of pollutants within (and near) the South Korea based on the sulfate tracking analyzer. The first episode demonstrated a secondary formation of nitrate and ammonium during the transport over the Yellow Sea while sulfate is mostly transported after being formed over the China, and the second episode demonstrated a dominant impact of boundary condition with active sulfate formation from gas-phase oxidation near the Seoul Metropolitan Area.

NUMERICAL SIMULATION OF TWO-DIMENSIONAL MICROORGANISM LOCOMOTION USING THE IMMERSED BOUNDARY METHOD (가상경계법을 적용한 2차원 미생물 이동에 관한 수치연구)

  • Maniyeri, Ranjith;Suh, Yong-Kweon;Kang, Sang-Mo
    • 한국전산유체공학회:학술대회논문집
    • /
    • 2009.11a
    • /
    • pp.164-169
    • /
    • 2009
  • Study on swimming of microorganisms like, sperm motility, cilia beating, bacterial flagellar propulsion has found immense significance in the field of biological fluiddynamics. Because of the complexity involved, it is challenging for the researchers to model such problems. Immersed boundary method has proved its efficacy in the field of biological fluiddynamics, The present work aims at performing a numerical study on the microorganism locomotion using the immersed boundary method proposed by Peskin[1]. A two-dimensional model of the microorganism is modeled as thin elastic filament described as a sine wave. The neutrally buoyant organism undergoing deformations is immersed in a viscous and incompressible fluid. The fluid quantities are described using Eulerian coordinates and the immersed body is represented by Lagrangian coordinates. The Eulerian and Lagrangian variables are connected by the Dirac delta function. The Navier-Stokes equations governing the fluid flow are solved using the fractional step method on a staggered Cartesian grid system. The developed numerical code in FORTRAN will be validated by comparing the numerical results with the available results.

  • PDF

Development of Numerical Code for Interior Ballistics and Analysis of Two-phase Flow according to Drag Models (강내탄도 전산해석 코드 개발과 항력 모델에 따른 이상유동 분석)

  • Sung, Hyung-Gun;Jang, Jin-Sung;Yoo, Seung-Young;Roh, Tae-Seong
    • Journal of the Korean Society of Propulsion Engineers
    • /
    • v.15 no.6
    • /
    • pp.38-46
    • /
    • 2011
  • In order to simulate the ignition-gas injection in the interior ballistics, a two-dimensional analytic code for two-phase flows has been developed. The Eulerian-Lagrangian approach and the low-dissipation simple high-resolution upwind scheme(LSHUS) have been adopted in the numerical code for the propellant combustion of the gun propelling charges. The ghost-cell extrapolation method has been used for the moving boundary in the chamber with the projectile movement. The calculation results of the developed code have been compared and verified through those of the dimensionless IBHVG2 code and the previous one-dimensional code. In comparison with the two-phase flows according to the drag models, the numerical analysis of the muzzle velocity has been affected by the drag model.

LES of Breakup and Atomization Characteristics of a Liquid Jet into Cross Turbulent Flow (난류 횡단류에 수직 분사 되는 액주의 분열 및 기화 특성에 관한 LES)

  • Yang, Seung-Joon;Koo, Ja-Ye;Sung, Hong-Gye;Yang, Vigor
    • Journal of the Korean Society of Propulsion Engineers
    • /
    • v.14 no.2
    • /
    • pp.1-9
    • /
    • 2010
  • LES(Large eddy simulation) of breakup and droplet atomization of a liquid jet into cross turbulent flow was performed. Two phase flow of gas and liquid phases were modeled by the mixed numerical scheme of both Eulerian and Lagrangian methods for gas and liquid droplet respectively. The breakup process of a liquid column and droplets was observed by implementing the blob-KH wave breakup model. The penetration depth into cross flow was comparable with experimental data for several variants of the liquid-gas momentum flux ratio by varying liquid injection velocity. SMD(Sauter Mean Diameter) distribution downstream of jet was analyzed.