• Ocean Systems Engineering
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• 제12권2호
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• pp.247-265
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• 2022

In the present study, we focus on the CFD simulations for the performance and the rotor-generated wake of a model-scale wind turbine which was designed for wave tank experiments. The CFD simulations with fully resolved rotor geometry are performed using MARIN's community-based open-source CFD code ReFRESCO. The absolute formulation method (AFM) is leveraged to model the rotating wind turbine. The k - ω SST turbulence model is adopted in the incompressible Reynolds Averaged Navier-Stokes (RANS) simulations. First, the thrust and torque coefficients, C_T and C_P, are calculated at different Tip Speed Ratios (TSR), and the results are compared against the experimental data and previous numerical results. The pressure distribution of the turbine blades at the 70% span is obtained and compared to the results obtained by other tools. Then, a verification study aiming at quantifying the discretization uncertainty of the turbine performance with respect to the grid resolution in the wake region is performed. Last, the rotor-generated wake at the TSR of 7 is presented and discussed.

• 한국정보통신학회논문지
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• 제17권5호
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• pp.1160-1167
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• 2013

네트워크 및 컴퓨팅 기술의 발달로 실생활에서 일어나는 다양한 현상을 수치적으로 계산하고 분석할 수 있는 웹 시뮬레이션 서비스가 활발히 사용되고 있다. 이 논문에서는 웹 기반 열유체 시뮬레이션을 제공하는 e-AIRS(e-Science Aerospace Integrated Research System) 서비스의 개선 및 활용에 대해 기술한다. 2008년부터 서비스된 e-AIRS는 안정성에 일부 문제가 있어 사용자가 종종 원활한 시뮬레이션을 수행하기 어려움이 있었다. 이 문제를 해결하기 위하여 화면 갱신 방법 개선, 서비스 분산처리, 개인별 시뮬레이션 작업량 할당, 데이터 로딩 시간 감소, 등의 개선 작업을 수행하였다. 개선 후 사용자가 110명에서 606명으로 증가했음에도 안정성에 대한 요구사항은 감소하여 효과적으로 개선이 이루어졌음을 알 수 있다. 매 학기마다 분석되는 시뮬레이션 서비스 활용 내역 및 사용자 요구사항은 보다 나은 서비스를 제공하기 위해 사용될 것이다.

• 한국전산유체공학회지
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• 제7권3호
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• pp.27-34
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• 2002

When caught in a fire inside a building or a tunnel the generated smoke is the main cause of the bad visibility, which makes it difficult for a person to find escape route. Therefore of the fire simulation it is required to visualize the simulated results of smoke realistically form a viewpoint of a person caught in a fire. In the present study, developed is a CFD post-processor which can visualize the object through smoke from the results of CFD fire simulation. Examples of some applications of the program are shown in the paper.

• 한국해양공학회지
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• 제17권6호
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• pp.7-15
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• 2003

A Digital Wave Tank simulation technique, based on a finite-difference method and a modified marker-and-cell (MAC) algorithm, is applied in order to investigate the characteristics of nonlinear Tsunami propagations and their interactions with a 2D sloping beach, Ohkushiri Island, and to predict maximum wove run-up around the island. The Navier-Stokes (NS) and continuity equation are governed in the computational domain, and the boundary values are updated at each time step, by a finite-difference time-marching scheme in the frame of the rectangular coordinate system. The fully nonlinear, kinematic, free-surface condition is satisfied by the modified marker-density function technique. The near shore Tsunami is assumed to be a solitary wave, and is generated from the numerical wave-maker in the developed Digital Wave Tank. The simulation results are compared with the experiments and other numerical methods, based on the shallow-water wave theory.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2005년도 추계 학술대회논문집
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• pp.49-53
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• 2005

This paper presents a multi-scale hybrid simulation for the design of a catalytic multi-tubular reactor with high performance. The multi-tubular reactor consists of shell and a large number of tubes in which various catalytic chemical reactions occur. To consider fluid dynamics in the shell-side and kinetics in the tube-side at the same time, commercial CFD package and process simulation tool are coupled. This hybrid approach allowed us to predict many kinds of meaningful results such as tube center temperature profile, heat transfer coefficients on the tube wall, temperature rise of cooling medium, pressure drop through shell and tube side, concentration profile of each chemical species along the tube, and so on., and to achieve the optimal reactor design.

• 한국유체기계학회 논문집
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• 제4권3호
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• pp.14-20
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• 2001

Numerical analysis of the three dimensional turbulent flow field in a complex valve trim is carried out to confirm the possibility whether this simulation tool can be used as a design tool or not. The simulation of the incompressible flow in a glove valve is performed by using the commercial code. CFD-ACEA utilizes the finite volume approach as a discretization scheme, and the pressure-velocity coupling is made from SIMPLEC algorithm in it. Four flow cases of the control valve are investigated, and the valve flow coefficient for each case is compared with the experimental data. Simulation results show a good agreement with the experiments, and it is observed that the cavitation model improves the simulation results.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2010년 춘계학술대회논문집
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• pp.17-20
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• 2010

An aerial target system is used for the purpose of experimental test and fire training of missile that newly developed and in mass production. Since the target drones of aerial target systems are monopolized by several major countries so that they are selling at a high price. In this paper, we present the CFD simulation results on a new target drone that Kyungan co. ltd is developing with their own technologies. The presented CFD simulation was conducted in the same conditions of a wind tunnel tests and we could obtain the simulation results of the lift and drag values were in errors by less than 15 percent compared to the experiment. The simulation results were used to determine the modified shapes of new prototype target drone that could fly safely.

• International Journal of Fluid Machinery and Systems
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• 제8권4호
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• pp.240-253
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• 2015

The objective of this paper is to evaluate the applicability of mass transfer cavitation models and determine appropriate numerical parameters for cavitating flow simulations. CFD simulations were performed for a NACA66 hydrofoil at cavitation numbers of 1.49 and 1.00, corresponding to steady sheet and unsteady sheet/cloud cavitating regimes using the Kubota and Merkle cavitation models. The Merkle model was implemented into CFX by User Fortran code. The Merkle cavitation model is found to give some improvements for cavitating flow simulation results for these cases. Turbulence modeling is also found to have an important contribution to the prediction quality of the simulations. The relationship between the turbulence viscosity modification, in order to take into account the local compressibility at the vapor/liquid interfaces, and the predicted numerical results is clarified. The limitations of current cavitating flow simulation techniques are discussed throughout the paper.

• 한국전산유체공학회지
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• 제12권1호
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• pp.22-27
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• 2007

Automobile underhood thermal and airflow simulation h α s been performed by using a commercial CFD program, FLUENT. To implement the radiation heat transfer effect to the underhood thermal and flow field, Discrete Ordinates Method(DOM) was used. The cooling fan was modeled by using the Multiple Reference Frame(MRF) technique. For the implementation of the heat exchangers, such as radiator and condenser, which are located in the front side of vehicle, the effectiveness-NTU model was used. The pressure drop throughout the heat exchangers was modeled as Porous media. For the validation of the current computational method, the coolant temperature at the inlet port of the radiator was compared with experimental data, and less than 3% error was observed. Finally, the composed model was used for the cooling fan spec determination process in the development of a new vehicle, and the results showed that the current CFD method could be successfully applied to the vehicle development process.

• 대한조선학회논문집
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• 제47권3호
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• pp.377-387
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• 2010

In this study, the turbulent free surface around KVLCC1 employed in the circular motion test simulation is numerically calculated using a commercial CFD(Computational Fluid Dynamics) code, FLUENT. Also, hydrodynamic forces and yaw moments around a ship model are calculated during the steady turning. Numerical simulations of the turbulent flows with free surface around KVLCC1 have been carried out by use of RANS equation based on calculation of hydrodynamic forces and yaw moments exerted upon the ship hull. Wave elevation is simulated by using the VOF method. VOF method is known as one of the most effective numerical techniques handling two-fluid domains of different density simultaneously. Boundary layer thickness and wake field are changed various yaw velocities of ship model during the steady turning. The calculated hydrodynamic forces are compared with those obtained by model tests.