• 제목/요약/키워드: Hydrodynamic Code

검색결과 177건 처리시간 0.033초

Unstructured Moving-Mesh Hydrodynamic Simulation

  • Yun, Kiyun;Kim, Juhan;Yoon, Suk-Jin
    • 천문학회보
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    • 제39권2호
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    • pp.65.2-65.2
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    • 2014
  • We present a new hydrodynamic simulation code based on the Voronoi tessellation for estimating the density precisely. The code employs both of Lagrangian and Eulerian description by adopting the movable mesh scheme, which is superior to the conventional SPH (smoothed particle hydrodynamics) and AMR (adaptive mesh refinement) schemes. The code first generates unstructured meshes by the Voronoi tessellation at every time step, and then solves the Riemann problem for all surfaces of each Voronoi cell so as to update the hydrodynamic states as well as to move current meshes. Besides, the IEM (incremental expanding method) is devised to compute the Voronoi tessellation to desired degree of speed, thereby the CPU time is turned out to be just proportional to the number of particles, i.e., O(N). We discuss the applications of our code in the context of cosmological simulations as well as numerical experiments for galaxy formation.

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동수력학 해석 기반 부유식 해양 플랫폼의 동적 운동 및 계류력 산정 (Estimation of Dynamic Motions and Mooring Forces for Floating Type Offshore Platform Based on Hydrodynamic Analysis)

  • 차주환;문창일;송창용
    • 한국해양공학회지
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    • 제26권2호
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    • pp.48-57
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    • 2012
  • This paper deals with numerical analyses in the context of estimations of hydrodynamic motions and dynamic loads for a floating type offshore platform using some exclusive simulation code such as code for the simulation of a floating type of offshore crane based on multi-body dynamics, along with the commercial code AQWA. Verifications of numerical models are carried out by comparing the RAO results from the simulation code. In the verification analyses, hydrodynamic motions are examined in the frequency domain for the floating type offshore platform according to the mooring lines. Both the hydrodynamic motions and dynamic loads are estimated for floating type offshore platforms equipped with the catenary type and taut mooring lines. A review and comparison are carried out for the numerically estimated results. The structural safety of the connection parts in an offshore structure such as a floating type offshore platform is one of the most important design criteria in view of fatigue life. The dynamic loads in the connecting area between a floating type offshore platform and its mooring lines are estimated in detail according to variations in the mechanical properties of the mooring lines. The dynamic tension load on the mooring lines is also estimated.

Split Hopkinson Pressure Bar(SHPB)에 의한 고 변형률 재료의 구성방정식 시뮬레이션

  • 이억섭;정주호;김종호
    • 한국정밀공학회:학술대회논문집
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    • 한국정밀공학회 1995년도 추계학술대회 논문집
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    • pp.724-727
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    • 1995
  • Dynamic deformation behavior under the high strain rate loading condition obtained with the aid of Split Hopkinson Pressure Bar(SHPB) technique is simulated by DYNA2D (an hydrodynamic code). A constitutive equation such as Johnson-Cook model is used by adjusting various parameters to fit experimentally determined dynamic stress-strain relationship.

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A Multi-Dimensional Thermal-Hydraulic System Analysis Code, MARS 1.3.1

  • Jeong, Jae-Jun;Ha, Kwi-Seok;Chung, Bub-Dong;Lee, Won-Jae
    • Nuclear Engineering and Technology
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    • 제31권3호
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    • pp.344-363
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    • 1999
  • A multi-dimensional thermal-hydraulic system analysis code, MARS 1.3.1, has been developed in order to have the realistic analysis capability of two-phase thermal-hydraulic transients for pressurized water reactor (PWR) plants. As the backbones for the MARS code, the RELAP5/MOD3.2.1.2 and COBRA-TF codes were adopted in order to take advantages of the very general, versatile features of RELAP5 and the realistic three-dimensional hydrodynamic module of COBRA-TF. In the MARS code, all the functional modules of the two codes were unified into a single code first. Then, the source codes were converted into the standard Fortran 90, and then they were restructured using a modular data structure based on "derived type variables" and a new "dynamic memory allocation" scheme. In addition, the Windows features were implemented to improve user friendliness. This paper presents the developmental work of the MARS version 1.3.1 including the hydrodynamic model unification, the heat structure coupling, the code restructuring and modernization, and their verifications.their verifications.

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Hydrodynamic analysis of the surface-piercing propeller in unsteady open water condition using boundary element method

  • Yari, Ehsan;Ghassemi, Hassan
    • International Journal of Naval Architecture and Ocean Engineering
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    • 제8권1호
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    • pp.22-37
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    • 2016
  • This article investigates numerical modeling of surface piercing propeller (SPP) in unsteady open water condition using boundary element method. The home code based on BEM has been developed for the prediction of propeller performance, unsteady ventilation pattern and cross flow effect on partially submerged propellers. To achieve accurate results and correct behavior extraction of the ventilation zone, finely mesh has generated around the propeller and especially in the situation intersection of propeller with the free surface. Hydrodynamic coefficients and ventilation pattern on key blade of SPP are calculated in the different advance coefficients. The values obtained from this numerical simulation are plotted and the results are compared with experiments data and ventilation observations. The predicted ventilated open water performances of the SPP as well as ventilation pattern are in good agreement with experimental data. Finally, the results of the BEM code/experiment comparisons are discussed.

Theoretical analysis on vibration characteristic of a flexible tube under the interaction of seismic load and hydrodynamic force

  • Lai, Jiang;He, Chao;Sun, Lei;Li, Pengzhou
    • Nuclear Engineering and Technology
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    • 제52권3호
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    • pp.654-659
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    • 2020
  • The reliability of the spent fuel pool instrument is very important for the security of nuclear power plant, especially during the earthquake. The effect of the fluid force on the vibration characteristics of the flexible tube of the spent fuel pool instrument needs comprehensive analysis. In this paper, based on the potential flow theory, the hydrodynamic pressures acting on the flexible tube were obtained. A mathematical model of a flexible tube was constructed to obtain the dynamic response considering the effects of seismic load and fluid force, and a computer code was written. Based on the mathematical model and computer code, the maximum stresses of the flexible tube in both safe shutdown earthquake and operating basis earthquake events on the spent fuel pool with three typical water levels were calculated, respectively. The results show that the fluid force has an obvious effect on the stress and strain of the flexible tube in both safe shutdown earthquake and operating basis earthquake events.

Hydrodynamic analysis of floating structures with baffled ARTs

  • Kim, San;Lee, Kang-Heon
    • Structural Engineering and Mechanics
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    • 제68권1호
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    • pp.1-15
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    • 2018
  • In ocean industry, free surface type ART (Anti Roll tank) system has been widely used to suppress the roll motion of floating structures. In those, various obstacles have been devised to obtain the sufficient damping and to enhance the controllability of freely rushing water inside the tank. Most of previous researches have paid on the development of simple mathematical formula for coupled ship-ARTs analysis although other numerical and experimental approaches exist. Little attention has been focused on the use of 3D panel method for preliminary design of free surface type ART despite its advantages in computational time and general capacity for hydrodynamic damping estimation. This study aims at developing a potential theory based hydrodynamic code for the analysis of floating structure with baffled ARTs. The sloshing in baffled tanks is modeled through the linear potential theory with FE discretization and it coupled with hydrodynamic equations of floating structures discretized by BEM and FEM, resulting in direct coupled FE-BE formulation. The general capacity of proposed formulation is emphasized through the coupled hydrodynamic analysis of floating structure and sloshing inside baffled ARTs. In addition, the numerical methods for natural sloshing frequency tuning and estimation of hydrodynamic damping ratio of liquid sloshing in baffled tanks undergoing wave exiting loads are developed through the proposed formulation. In numerical examples, effects of natural frequency tuning and baffle ratios on the maximum and significant roll motions are investigated.

Monte Carlo Method에 의한 GaAs의 Hydrodynamic Model Parameter의 추출 (Extraction of Hydrodynamic Model Parameters for GaAs Using the Monte Carlo Method)

  • 박성호;한백형
    • 대한전자공학회논문지
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    • 제27권3호
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    • pp.63-71
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    • 1990
  • Hydrodynamic model에 의해서 submicron GaAs device를 simulation 할 때 필요한 hydrodynamic model parameter 들을 Monte Carlo code를 개발하여 추출하였다. GaAs 전도대의 밴드구조로 $\Gamma$, L, X세개의 valley를 고려하였고, 산란기구로는 polar optic phonon, acoustic phonon, equivalent intervalley, non-equivalent intervalley, ionized impurity 및 piezoelectric scattering을 고려하였다. 계산으로부터 얻은 속도 - 전계 곡선은 실험결과와 잘 일치하였고, 다른 연구자들이 소자 시뮬레이션에 사용할 수 있도록 모델 파라메터들을 표로 제시하였다.

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유동 방향 변화에 따른 잠수함 주위의 유동 특성과 유체동역학적 계수의 변화 (The Variation of Flow Field and Hydrodynamic Coefficients of Submarine by Changes of Angle of Attack and Yaw Angle)

  • 장진호;박원규
    • 대한조선학회논문집
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    • 제43권4호
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    • pp.460-466
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    • 2006
  • The three-dimensional RANS equations were applied to analyze the flow field of a submarine. To validate the code, the DARPA SUBOFF bare hull and an eliipsoid at angles of attack of $10^{\circ}\;and\;30^{\circ}$ were simulated and good agreement with experiments was obtained. After the code validation, the flows over the full configuration of DARPA SUBOFF model having a fairwater and four stern appendages were simulated at four angles of attack $(0^{\circ},\;10^{\circ},\;20^{\circ},\;30^{\circ})$ and three yaw angles $(10^{\circ},\;20^{\circ},\;30^{\circ})$ Specifically, the pressure contours and streamlines of fairwater and stern appendage were compared as the angle of attack and yaw angle changed. The variations of hydrodynamic forces were also calculated.