• Title/Summary/Keyword: Eulerian Approach

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Nonlinear Liquid Sloshing Analysis in a Cylindrical Container by Arbitrary Lagrangian-Eulerian Approach (Arbitrary Lagrangian-Eulerian 기법에 의한 원통형 유체저장구조물 내부유체의 비선형 슬러싱 해석)

  • Kwon, Hyung-O;Cho, Kyung-Hwan;Kim, Moon-Kyum;Lim, Yun-Mook
    • Journal of the Earthquake Engineering Society of Korea
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    • v.9 no.2 s.42
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    • pp.71-80
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    • 2005
  • The solution to a liquid sloshing problem is challenge to the field of engineering. This is not only because the dynamic boundary condition at the free surface is nonlinear, but also because the position of the free surface varies with time in a manner not known a priori. Therefore, this nonlinear phenomenon, which is characterized by the oscillation of the unrestrained free surface of the fluid, is a difficult mathematical problem to solve numerically and analytically. In this study, three-dimensional boundary element method(BEM), which is based on the so-called an arbitrary Lagrangian-Eulerian(ALE) approach for the fluid flow problems with a free surface, was formulated to solve the behavior of the nonlinear free surface motion. An ALE-BEM has the advantage to track the free surface along any prescribed paths by using only one displacement variable, even for a three-dimensional problem. Also, some numerical examples were presented to demonstrate the validity and the applicability of the developed procedure.

Eulerian-Lagrangian Modeling of One-Dimensional Dispersion Equation in Nonuniform Flow (부등류조건에서 종확산방정식의 Eulerian-Lagrangian 모형)

  • 김대근;서일원
    • Journal of Environmental Science International
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    • v.11 no.9
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    • pp.907-914
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    • 2002
  • Various Eulerian-Lagrangian models for the one-dimensional longitudinal dispersion equation in nonuniform flow were studied comparatively. In the models studied, the transport equation was decoupled into two component parts by the operator-splitting approach; one part is governing advection and the other is governing dispersion. The advection equation has been solved by using the method of characteristics following fluid particles along the characteristic line and the results were interpolated onto an Eulerian grid on which the dispersion equation was solved by Crank-Nicholson type finite difference method. In the solution of the advection equation, Lagrange fifth, cubic spline, Hermite third and fifth interpolating polynomials were tested by numerical experiment and theoretical error analysis. Among these, Hermite interpolating polynomials are generally superior to Lagrange and cubic spline interpolating polynomials in reducing both dissipation and dispersion errors.

Using a Lagrangian-Lagrangian approach for studying flow behavior inside a bubble column

  • YoungWoo Son;Cheol-O Ahn;SangHwan Lee
    • Nuclear Engineering and Technology
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    • v.55 no.12
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    • pp.4395-4407
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    • 2023
  • Bubble columns are widely encountered in several industries, especially in the field of nuclear safety. The Eulerian-Eulerian and the Eulerian-Lagrangian methods are commonly used to investigate bubble columns. Eulerian approaches require additional tasks such as strict volume conservation at the interface and a predefined well-structured grid. In contrast, the Lagrangian approach can be easily implemented. Hence, we introduce a fully Lagrangian approach for the simulation of bubble columns using the discrete bubble model (DBM) and moving particle semi-implicit (MPS) methods. Additionally, we propose a rigorous method to estimate the volume fraction accurately, and verified it through experimental data and analytical results. The MPS method was compared with the experimental data of Dambreak. The DBM was verified by analyzing the terminal velocity of a single bubble for each bubble size. It agreed with the analytical results for each of the four drag correlations. Additionally, the improved method for calculating the volume fraction showed agreement with the Ergun equation for the pressure drop in a packed bed. The implemented MPS-DBM was used to simulate the bubble column, and the results were compared with the experimental results. We demonstrated that the MPS-DBM was in quantitative agreement with the experimental data.

An ALE Finite Element Formulation for Rigid-Viscoplatic Materials and Its Application to Axisymmetric Extrusion through Square Dies (ALE 묘사에 근거한 강-점소성 유한요소 수식화와 축대칭 평금형 압출에의 적용)

  • 강연식;양동열
    • Transactions of Materials Processing
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    • v.3 no.2
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    • pp.156-166
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    • 1994
  • An arbitrary Lagrangian-Eulerian (ALE) finite element method has been developed. The finite element formation is derived and implemented for rigid-viscoplastic materials. The developed computer program is applied to the analysis of axisymmetric square die extrusion, which has many difficulties with updated Lagrangian approach. The results are compared with those from updated Largrangian approach. The results are compared with those from updated Lagrangian finite element program. Updating scheme of time dependent variables and mesh control are also examined.

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Development of Code for Numerical Analysis of Interior Ballistics using Eulerian-Lagrangian Approach and SMART scheme (Eulerian-Lagrangian 접근법과 SMART scheme을 이용한 강내탄도 전산해석 코드 개발)

  • Sung, Hyung-Gun;Jang, Jin-Sung;Lee, Sang-Bok;Choi, Dong-Whan;Roh, Tae-Seong;Jang, Young-Jae
    • Journal of the Korea Institute of Military Science and Technology
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    • v.13 no.3
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    • pp.349-357
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    • 2010
  • In this paper, a numerical code for the interior ballistics has been investigated. The Eulerian-Lagrangian approach and the SMART scheme have been used in the numerical code for the grain combustion. The translational kinetic energy of the projectile and work done against barrel friction have been considered only. The ghost cell extrapolation method has been used for the chamber change with the projectile movement. The calculation results of the numerical code have been compared and verified through those of IBHVG2 code.

Eulerian Particle Flamelet Modeling for Combustion Processes of Bluff-Body Stabilized Methanol-Air Turbulent Nonpremixed Flames

  • Kim, Seong-Ku;Kang, Sung-Mo;Kim, Yong-Mo
    • Journal of Mechanical Science and Technology
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    • v.20 no.9
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    • pp.1459-1474
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    • 2006
  • The present study is focused on the development of the RIF (Representative Interactive Flamelet) model which can overcome the shortcomings of conventional approach based on the steady flamelet library. Due to the ability for interactively describing the transient behaviors of local flame structures with CFD solver, the RIF model can effectively account for the detailed mechanisms of $NO_x$ formation including thermal NO path, prompt and nitrous $NO_x$ formation, and reburning process by hydrocarbon radical without any ad-hoc procedure. The flamelet time of RIFs within a stationary turbulent flame may be thought to be Lagrangian flight time. In context with the RIF approach, this study adopts the Eulerian Particle Flamelet Model (EPFM) with mutiple flamelets which can realistically account for the spatial inhomogeneity of scalar dissipation rate. In order to systematically evaluate the capability of Eulerian particle flamelet model to predict the precise flame structure and NO formation in the multi-dimensional elliptic flames, two methanol bluffbody flames with two different injection velocities are chosen as the validation cases. Numerical results suggest that the present EPFM model has the predicative capability to realistically capture the essential features of flame structure and $NO_x$ formation in the bluff-body stabilized flames.

FLUID-STRUCTURE INTERACTION ANALYSIS OF LIQUID STORAGE STRUCTURES (액체 저장구조물의 유체-구조물 상호작용 해석)

  • 윤정방;김진웅;서정문;전영선
    • Computational Structural Engineering
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    • v.5 no.4
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    • pp.103-111
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    • 1992
  • In this paper, liquid sloshing effects in rectangular storage structures for spent fuel under earthquake loadings are investigated. Eulerian and Lagrangian approaches are presented. The Eulerian approach is carried out by solving the boundary value problem for the fluid motion. In the Lagrangian approach, the fluid as well as the storage structure is modelled by the finite element method. The fluid region is discretized by using fluid elements. The (1*1)-reduced integration is carried out for constructing the stiffness matrices of the fluid elements. Seismic analysis of the coupled system is carried out by the response spectra method. The numerical results show that the fluid forces on the wall obtained by two approaches are in good agreements. By including the effect of the wall flexibility, the hydrodynamic forces due to fluid motion can be increased very significantly.

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Numerical Modeling of One-Dimensional Longitudinal Dispersion Equation using Eulerian-Lagrangian Method (Eulerian-Lagrangian 방법을 이용한 1차원 종확산방정식의 수치모형)

  • 서일원;김대근
    • Water for future
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    • v.27 no.2
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    • pp.155-166
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    • 1994
  • Various Eulerian-Lagrangian numerical models for the one-dimensional longitudinal dispersion equation are studied comparatively. In the model studied, the transport equation is decoupled into two component parts by the operator-splitting approach ; one part governing adveciton and the other dispersion. The advection equation has been solved using the method of characteristics following fluid particles along the characteristic line and the results are interpolated onto an Eulerian grid on which the dispersion equation is solved by Crank-Nicholson type finite difference method. In solving the advection equation, various interpolation schemes are tested. Among those, Hermite interpolation polynomials are superior to Lagrange interpolation polynomials in reducing dissipation and dispersion errors in the simulation.

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EULERIAN-BASED ANALYSIS SYSTEM FOR SIMULATION OF AIRFOIL ICING (Eulerian 기반 에어포일 결빙 해석 시스템 연구)

  • Jung, S.K.;Oh, J.G.;Chun, S.H.;Moon, H.;Myong, R.S.;Cho, T.H.
    • 한국전산유체공학회:학술대회논문집
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    • 2010.05a
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    • pp.460-463
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    • 2010
  • Ice accretion on aircraft surface can greatly impair the aerodynamic performance of aircraft. As an alternative to the traditional Lagrangian particle tracking approach, an Eulerian-based droplet impingement and ice accretion code for air flows containing water droplets was developed A CFD solver was also developed to solve the clean airflow. The results of present method were compared with experimental data and previous icing codes such as LEWICE and FENSAP-ICE and were confirmed to show good agreement each other in qualitative and quantitative ways.

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