• 대한기계학회:학술대회논문집
• /
• 대한기계학회 2008년도 추계학술대회B
• /
• pp.2410-2414
• /
• 2008

Human heart valves diseased by congenital heart defects, rheumatic fever, bacterial infection, cancer may cause stenosis or insufficiency in the valves. Treatment may be with medication but often involves valve repair or replacement (insertion of an artificial heart valve). Bileaflet mechanical heart valves (BMHVs) are widely implanted to replace the diseased heart valves, but still suffer from complications such as hemolysis, platelet activation, tissue overgrowth and device failure. These complications are closely related to both flow characteristics through the valves and leaflet dynamics. In this study, the physiological flow interacting with the moving leaflets in a bileaflet mechanical heart valve (BMHV) is simulated with a strongly coupled implicit fluid-structure interaction (FSI) method which is newly organized based on the Arbitrary-Lagrangian-Eulerian (ALE) approach and the dynamic mesh method (remeshing) in FLUENT. The simulated results are in good agreement with previous experimental studies. This study shows the applicability of the present FSI model to the complicated physics interacting between fluid flow and moving boundary.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제12권1호
• /
• pp.387-398
• /
• 2020

In the design stage of the very large container ships, some methodologies for the whipping effects have been developed, but most of them are based on single sea state. We developed a methodology that considers multiple sea states. Fluid-structure Interaction (FSI) analyses with one dimensional structural model were carried out to capture slamming-induced transient whipping behaviors. Because of the nature of random phases of the applied wave spectra, the required period for entire FSI analyses was determined from the convergence study where the whipping effect became stable. Low pass filtering was applied to the transient whipping responses to obtain the hull girder bending moment processes. Peak counting method for the filtered whipping responses was used to obtain collection of the vertical bending moment peaks. The whipping effect from this new method is compared with that from based on single sea state approach. The efficiency and advantage of the new methodology are presented.

• International Journal of Naval Architecture and Ocean Engineering
• /
• 제6권3호
• /
• pp.652-669
• /
• 2014

This paper concerns the kinematic characteristics of a coupling device in a deep-seabed mining system. This coupling device connects the buffer system and the flexible pipe. The motion of the buffer system, flexible pipe and mining robot are affected by the coupling device. So the coupling device should be considered as a major factor when this device is designed. Therefore, we find a stable kinematic device, and apply it to the design coupling device through this study. The kinematic characteristics of the coupling device are analyzed by multi-body dynamics simulation method, and finite element method. The dynamic analysis model was built in the commercial software DAFUL. The Fluid Structure Interaction (FSI) method is applied to build the deep-seabed environment. Hydrodynamic force and moment are applied in the dynamic model for the FSI method. The loads and deformation of flexible pipe are estimated for analysis results of the kinematic characteristics.

• 한국추진공학회지
• /
• 제26권5호
• /
• pp.35-43
• /
• 2022

본 연구에서는 고체추진제를 사용하는 closed bomb test(CBT)의 연소에 대한 정밀 모델링 및 해석을 수행하였다. 기상과 고상을 동시에 해석하기 위해 fluid structure interaction(FSI) 기법을 사용하였으며 기체상과 그레인의 연소해석은 Eulerian 방법을, 그레인의 이동은 Lagrangian 방법을 적용하였다. 고체상의 그레인과 연소가스의 상호 작용은 소스텀을 통해 완전 결합(fully coupled) 되도록 하였다. 그레인의 연소거리와 연소면의 이동을 모사하기 위하여 volume of fluid(VOF) 방법을 사용하였고, 그레인에 작용하는 힘은 그레인 연소면에 작용하는 압력과 중력을 고려하고, VOF의 속도항에 그레인 연소속도와 그레인 이동속도를 고려하였다. 개발한 수치모델을 바탕으로 1개와 3개 그레인에 대한 연소해석을 수행하여 실험결과와 비교 검증하였다. 연소시에 나타나는 압력 섭동에 대한 음향장을 분석하였다.

• Journal of Biosystems Engineering
• /
• 제28권2호
• /
• pp.127-136
• /
• 2003

The top-to-bottom compression strength of corrugated board box is the most important mode of loading during it's no, and it depends largely on the edgewise compression strength of the corrugated board in the cross-machine direction and to a considerable extent on the flexural stiffness in both principal directions (CD; cross-machine direction, MD; machine direction) of the corrugated board. Corrugated board is a sandwich structure with an orthotropic property. The purpose of this study was to elucidate the principal design parameters for board combination of corrugated board from the viewpoint of bending strength through the finite element analysis [FEA] fur the various corrugated board. In general, the flexural stiffness [FS] in the MD was 2-3 times larger than that in the CD, and the effect of liner for the FS of corrugated board was much bigger than that of corrugating medium. The flexural stiffness index [FSI] was high when the stiffness of liner was in the order of inner, outer, and middle liner in double-wall corrugated board [DW], and the effect of the stiffness arrangement or itself reinforcement of corrugating medium on the FSI was not high. In single-wall corrugated board [SW] with DW. the variation of FSI with itself stiffness reinforcement of liner was much bigger than that with stiffness arrangement of liner. The highest FSI was at the ratio of about 2:1:2 for basis weight distribution of outer, middle, and inner liner if the stiffness of liner and total basis weight of corrugated board were equal in DW Secondarily. basis weight was in the order of inner, outer, and middle liner. However, the variation of FSI with basis weight distribution between liner and corrugating medium was much bigger than that with itself basis weight distribution ratio of liner and corrugating medium respectively in both DW and SW. md the FSI was high as more total basis weight was divided into liner. These phenomena fur board combination of corrugated board based on the FEA were well verified by experimental investigation.

• 한국전산구조공학회논문집
• /
• 제29권2호
• /
• pp.179-185
• /
• 2016

본 연구에서는 고체추진기관의 2차원 축대칭 FSI 해석에서 CSS 및 ISS 기법의 수치 안정성을 고찰하였다. 이를 위하여 CSS 및 ISS 기법을 2차원 축대칭 FSI 수치해석 알고리즘에 구현한 프로그램을 작성하고, 이를 ACM 및 BCM 고체추진기관의 복합거동 해석에 사용하였다. 해석 결과들을 비교 분석하여 ISS 기법이 고체추진기관 FSI 해석의 수치 안정성 개선에 효과적인지 검토하였다. 연구결과, ISS 기법을 적용한 FSI 해석은 시스템 시간간격이 작아질수록 수치적 수렴성을 보이며, CSS 기법과 다르게 시간이 진행되어도 수치해의 진동이 발산하지 않는 것을 확인할 수 있었다. 이를 통하여 ISS 기법을 사용하면 ACM 및 BCM의 FSI 해석에 CSS 기법을 이용할 시 나타나는 수치 불안정성을 개선할 수 있음을 확인하였다.

• Ocean Systems Engineering
• /
• 제7권3호
• /
• pp.299-318
• /
• 2017

The paper aims at illustrating several key issues and ongoing efforts for development of a reliable fully-Lagrangian particle-based solver for simulation of hydroelastic slamming. Fluid model is founded on the solution of Navier-Stokes along with continuity equations via an enhanced version of a projection-based particle method, namely, Moving Particle Semi-implicit (MPS) method. The fluid model is carefully coupled with a structure model on the basis of conservation of linear and angular momenta for an elastic solid. The developed coupled FSI (Fluid-Structure Interaction) solver is applied to simulations of high velocity impact of an elastic aluminum wedge and hydroelastic slammings of marine panels. Validations are made both qualitatively and quantitatively in terms of reproduced pressure as well as structure deformation. Several remaining challenges as well as important key issues are highlighted. At last, a recently developed multi-scale MPS method is incorporated in the developed FSI solver towards enhancement of its adaptivity.

• 한국전산구조공학회:학술대회논문집
• /
• 한국전산구조공학회 2009년도 정기 학술대회
• /
• pp.300-303
• /
• 2009

본 논문에서는 유체-구조물 상호작용(Fluid-Structure interaction;FSI)에 관한 새로운 수치적 접근 방법의 제안과 타당성 검토가 목적이다. 기존의 유체 관내 유동에서는 유체-구조물 상호작용방법을 이용하여 해석하였으나 해석과정과 수치적 효율성에 문제점이 있다. 본 논문은 다공질 매체 거동을 이용하여 관내 유체 유동해석이 제안된다. 제안된 기법은 기존의 방법이 갖는 모델링의 어려움을 개선하고, 비교적 복잡한 과정이 수행되어 많은 계산 시간이 요구되어지는 수치적 효율성이 개선되었다. 또한 다공질 매체 거동에서 중요요소인 침투성과 유체-구조물 상호작용의 중요요소인 유체와 구조물경계의 마찰사이의 관계가 도출되었다.

• 한국기계가공학회지
• /
• 제10권4호
• /
• pp.31-37
• /
• 2011

Fuel tank sloshing noise of vehicle is caused by flow impact on the tank wall during sudden braking, and the sloshing vibration of tank wall is a coupled phenomenon of the fuel inside tank and tank wall structure. Therefore, Fluid-Structure Interface(FSI) analysis technology should be adopted to predict accurately the sloshing vibration. In this study, FSI approach was employed to analyze sloshing phenomenon for a simple tank model with velocity change of the actual vehicle test. First, the simulated results for rigid tank model were compared with those for deformable tank model. Next, influence of baffle location and shape of baffle holes on the acceleration magnitude and the maximum stress of tank wall was investigated. In addition, sloshing analysis for tank with another baffle type was carried out.

• 한국전산유체공학회:학술대회논문집
• /
• 한국전산유체공학회 2010년 춘계학술대회논문집
• /
• pp.295-304
• /
• 2010

The paper summarizes the VIV-related research with the focus on flexible riser and pipe models subject to various engineering conditions. First of all, a series of numerical simulations for the purpose of validating the efficiency of FSI solution approach (ANSYS MFX) has been performed. The comparison between the simulation and the experimental data shows that the present FSI solution method is capable of giving acceptable estimation to VIV problems. As a meaningful application to engineering problems, some tentative simulation cases which are difficult to carry out in experiment, such as a flexible pipe with internal flow and multi-assembled pipes, have been successfully carried out. The coupling mechanism between vortex shedding and the VIV has been well interpreted.