• Wind and Structures
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• 제36권6호
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• pp.423-434
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• 2023

Aerodynamic force coefficients are generally obtained from traditional wind tunnel tests or computational fluid dynamics (CFD). Unfortunately, the techniques mentioned above can sometimes be cumbersome because of the cost involved, such as the computational cost and the use of heavy equipment, to name only two examples. This study proposed to build a deep neural network model to predict the aerodynamic force coefficients based on data collected from CFD simulations to overcome these drawbacks. Therefore, a series of CFD simulations were conducted using different geometric parameters to obtain the aerodynamic force coefficients, validated with wind tunnel tests. The results obtained from CFD simulations were used to create a dataset to train a multilayer perceptron artificial neural network (ANN) model. The models were obtained using three optimization algorithms: scaled conjugate gradient (SCG), Bayesian regularization (BR), and Levenberg-Marquardt algorithms (LM). Furthermore, the performance of each neural network was verified using two performance metrics, including the mean square error and the R-squared coefficient of determination. Finally, the ANN model proved to be highly accurate in predicting the force coefficients of similar bridge sections, thus circumventing the computational burden associated with CFD simulation and the cost of traditional wind tunnel tests.

• Nuclear Engineering and Technology
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• 제56권5호
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• pp.1687-1697
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• 2024

This study presents the Supporting platform for reactor fine flow characteristics calculation and analysis (Cilian platform), a user-friendly tool that supports the analysis and optimization of pressurized water reactor (PWR) cores with mixing vanes using computational fluid dynamics (CFD) computing. The Cilian platform allows for easy creation and optimization of PWR's main CFD calculation schemes and autonomously manages CFD calculation and analysis of PWR cores, reducing the need for human and computational resources. The platform's key features enable efficient simulation, rapid solution design, automatic calculation of core scheme options, and streamlined data extraction and processing techniques. The Cilian platform's capability to call external CFD software reduces the development time and cost while improving the accuracy and reliability of the results. In conclusion, the Cilian platform exemplifies an innovative solution for efficient computational fluid dynamics analysis of pressurized water reactor (PWR) cores. It holds great promise for driving advancements in nuclear power technology, enhancing the safety, efficiency, and cost-effectiveness of nuclear reactors. The platform adopts a modular design methodology, enabling the swift and accurate computation and analysis of diverse flow regions within core components. This design approach facilitates the seamless integration of multiple computational modules across various reactor types, providing a high degree of flexibility and reusability.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.221-223
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• 2010

Considering the similarity between fluid vortex and arrhythmogenic reentrant waves in heart, we applied the non-dimensionalization method in fluid dynamics to arrhythmia analysis and discovered a new non-dimensional simulation results, there was a threshold value of the number that resulted in the induction of a reentrant wave.

• 한국가시화정보학회:학술대회논문집
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• 한국가시화정보학회 2003년도 추계학술대회 논문집
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• pp.51-54
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• 2003

Fluid is an effective element in computer animation. Recently, the techniques from CFD have been actively applied to CG production. In this paper, we describe our fluid animation system which implements a variety of established simulation and rendering methods. We also explain our new techniques such as chemical reaction and hardware-assisted fluid animation that are being developed to enhance the features of our software system.

• Korea-Australia Rheology Journal
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• 제21권3호
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• pp.161-173
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• 2009

This study analyzes especially drag and lift models recently developed for fluid-solid, fluid-fluid or liquid-liquid two-phase flows to understand their applicability on the computational fluid dynamics, CFD modeling of pulsatile blood flow. Virtual mass effect and the effect of red blood cells, RBCs aggregation on CFD modeling of blood flow are also shortly reviewed to recognize future tendencies in this field. Recent studies on two-phase flows are found as very useful to develop more powerful drag-lift models that reflect the effects of blood cell's shape, deformation, concentration, and aggregation.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 춘계학술대회논문집
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• pp.510-513
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• 2008

The traditional computational fluid or structure dynamics analysis approaches have contributed to solve many delicate engineering problems. But for the most of recent engineering problems which are influenced by fluid-structure interaction effect strongly, traditional individual approaches have limited analysis abilities for the exact simulation. Owing to above-mentioned reason, nowadays fluid-structure interaction analysis has become a matter of concern and interest. FSI analysis require several unprecedented techniques for the combining individual analysis tool into integrated analysis tool. The Arbitrary Lagrangian-Eulerian(ALE, in short) method is the new description of continum motion,which combines the advantages of the classical kinematical descriptions, i.e. Lagrangian and Eulerian description, while minimizing their respective drawbacks. In this paper, the ALE description is adapted to simulate fluid-structure interaction problems. An automatic re-mesh algorithm and a fluid-structure coupling process are included to analyze the interaction and moving motion during the 2-D axisymmetric solid rocket interior FSI phenomena simulation.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2006년도 춘계학술대회논문집
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• pp.959-963
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• 2006

A three-dimensional elastic blood vessel model with internal diameter variation is considered to investigate internal flow characteristics and effects of structural deformation. Also, computational analyses for both the rigid model and the fully-coupled FSI model have been conducted in order to compare the shear stress, pressure distribution, and flow velocity in detail. A 70% narrowing area of asymmetric blood vessel model was especially investigated to show the versatility of fluid-structure interaction phenomenon. The results reveal that effect of fluid-structure interaction is very important to accurately investigate the flow characteristics of the blood vessel.

• 대한기계학회논문집B
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• 제29권10호
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• pp.1139-1147
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• 2005

The shape optimal design of the plate-fin type heat sink with vortex generator is performed to minimize the pressure loss subjected to the desired maximum temperature numerically. Evaluation of the performance function, in general, is required much computational cost in fluid/thermal systems. Thus, global approximate optimization techniques have been introduced into the optimization of fluid/thermal systems. In this study, Kriging method Is used to obtain the optimal solutions associated with the computational fluid dynamics (CFD). The results show that when the temperature .rise is less than 40 K, the optimal design variables are $B_1=2.44\;mm,\;B_2=2.09\;mm$, and t=7.58 mm. Kriging method can dramatically reduce computational time by 1/6 times compared to SQP method so that the efficiency of Kriging method can be validated.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2017년도 제48회 춘계학술대회논문집
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• pp.606-608
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• 2017

터보프롭 엔진의 배기덕트에 구조적 안정성을 검토하기 위해 유동해석을 수행하였다. 항공기의 비행조건에 따라 작용하는 추력과 전단력을 산출하기 위해 배기덕트내의 관내유동과 배기덕트 플랜지 방향의 유동을 Fluent 소프트웨어로 해석을 수행하여 추력, 전단력, 벤딩모멘트 값을 얻을 수 있었다. 해석결과, 허용 하중값을 초과하지 않음을 확인하였다.

• 한국항공우주학회지
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• 제38권6호
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• pp.547-556
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• 2010

항공기의 안전성 확보 및 투하되는 탄의 정확도 증대를 위한 새로운 개념의 활공비행체 개발이 많은 기업에서 진행 중에 있다. 항공기의 장착 공간 및 활공거리 증대를 고려하여 세장비가 큰 전개되는 날개를 채택하는 것이 일반적이다. 큰 세장비의 날개 구조물은 상대적으로 낮은 강성에 의하여 과도한 탄성변형 뿐 아니라 플러터 발생의 가능성이 높아지게 된다. 본 연구는 큰 세장비 날개에 대하여 유체-공력 연계기법을 이용, 구조변형에 의한 공력특성의 변화 및 플러터 발생가능성에 대하여 검토하였다. 공기력 계산을 위하여 FLUENT 코드가 구조 동특성 해석을 위하여 ABAQUS 상용코드가 사용되었으며, 국부지지 방사기저함수로 구성된 Code-bridge를 이용한 입력 자료의 보간 및 사상을 수행하였다. 해석 결과 고려된 활공 조건에서 구조 변형에 의한 공력 특성의 변화가 발생하는 것이 관측되었으며, 이에 의한 진동도 계속적으로 발생되는 것으로 표현되었다.