• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.36 no.3
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• pp.220-228
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• 2008

In this study the aerodynamic characteristics of a canard-controlled missile with freely spinning tailfins were investigated by using a semi-empirical method and a CFD code. The mean aerodynamic coefficients for the rolling and roll damping moments were first calculated and then used to predict the roll-rate of freely spinning tailfins. The calculation of roll-rate in the CFD code was carried out by combining a Chimera overset grid system and 6-DOF analysis module. The predicted roll-rate was in good agreement with the experimental data for the roll and yaw canard control inputs. It was also shown that the results are in good agreement with the prediction by a CFD code. This indicates that the semi-empirical method can be used to predict the roll-rate of a canard-controlled missile with freely spinning tailfins.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.3
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• pp.180-188
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• 2014

Hyundai Motor Group(HMG) carried out experimental investigation of sunroof buffeting phenomena on a simplified car model called Hyundai simplified model(HSM). HMG invited participation from commercial CFD vendors to perform numerical investigation of sunroof buffeting for HSM model with a goal to determine whether CFD can predict sunroof buffeting behavior to sufficient accuracy. ANSYS Korea participated in this investigation and performed numerical simulations of sunroof buffeting for HSM using ANSYS fluent, the general purpose CFD code. First, a flow field validation is performed using closed sunroof HSM model for 60 km/h wind speed. The velocity profiles at three locations on the top surface of HSM model are predicted and compared with experimental measurement. Then, numerical simulations for buffeting are performed over range of wind speeds, using advanced scale resolving turbulence model in the form of detached eddy simulation (DES). Buffeting frequency and buffeting level are predicted in simulation and compared with experimental measurement. With reference to comparison between experimental measurements with CFD predictions of buffeting frequency and level, conclusion are drawn about predictive capabilities of CFD for real vehicle development.

• 한국연소학회:학술대회논문집
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• 2000.05a
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• pp.67-75
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• 2000

Computational fluid dynamics(CFD) analysis of the thermal flow in a municipal solid waste(MSW) incinerator combustion chamber provides crucial insight on the incinerator performance. However, the combustion of the waste bed is typically treated as an arbitrarily selected profile of combustion gas. A strategy for simultaneous simulation of the waste bed combustion and the thermal flow fields in the furnace chamber was introduced to substitute the simple inlet condition. A waste bed combustion model was constructed to predict the progress of combustion in the bed and corresponding generation of the gas phase species, which assumes the moving bed as a packed bed of homogeneous fuel particles. When coupled with CFD, it provides boundary conditions such as gas temperature and species distribution over the grate, and receives radiative heat flux from CFD. The combined simulation successfully predicted the physical processes of the waste bed combustion and its interaction with the flow fields for various design and operating parameters, which was limited in the previous CFD simulations.

• Journal of Aerospace System Engineering
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• v.2 no.2
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• pp.46-50
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• 2008

Aerodynamic characteristics, such as drag and lift, play an important role in automobile design under certain speed conditions. Such characteristics are essential to design an automobile since they are directly related to automobile's performance such as passenger safety and fuel consumption. There is a huge demand for the automobile to have safe performance at high speed. Reduction in drag is also important and it could lead to the solution of air flow induced noise and dust problems. The objective of this research is to find out the aerodynamic differences between conventional side mirror and a modified one using CFD. Although drag generated around a side mirror is only about 7% of the total drag when a car runs, it is very closely related to driver's field of vision and noise generation. CFD simulation of the flowfield around a car side-view mirror was performed using a commercial code; Gambit and FLUENT.

• Journal of the Society of Naval Architects of Korea
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• v.45 no.4
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• pp.361-369
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• 2008

The optimized distance between skegs and angle of the skeg for a standard twin-skeg type LNG carrier were presented using the CFD and model tests. The evaluation method of self-propulsion performance was derived based on the results of CFD and confirmed the validity through model tests. The analyses to assess self-propulsion performance using CFD were shown by flow line patterns on the skeg surface, nominal wake distribution in the propeller plane and the evaluation for flow balance around stern skegs. The optimized ship that was applied to the optimized two design parameters in stern skeg arrangement for target ship was derived in this work. Finally speed performance of mother ship which is existing ship and optimized ship were compared through CFD and model tests. And the usefulness about the evaluation method of self-propulsion performance was reconfirmed.

• International Journal of Naval Architecture and Ocean Engineering
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• v.1 no.2
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• pp.89-94
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• 2009

The current focus of development in industrial Computational Fluid Dynamics (CFD) is integration of CFD into Computer-Aided product development, geometrical optimisation, robust design and similar. On the other hand, in CFD research aims to extend the boundaries of practical engineering use in "non-traditional" areas. Requirements of computational flexibility and code integration are contradictory: a change of coding paradigm, with object orientation, library components, equation mimicking is proposed as a way forward. This paper describes OpenFOAM, a C++ object oriented library for Computational Continuum Mechanics (CCM) developed by the author. Efficient and flexible implementation of complex physical models is achieved by mimicking the form of partial differential equation in software, with code functionality provided in library form. Open Source deployment and development model allows the user to achieve desired versatility in physical modeling without the sacrifice of complex geometry support and execution efficiency.

• Journal of Environmental Impact Assessment
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• v.21 no.1
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• pp.133-142
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• 2012

Convection Current Circulation System(CCCS) in stratified reservoir controls development of anaerobic condition and algal bloom during summer. In order to increase the CCCS effectiveness, we analyze diverse design parameters to make optimize the flow pattern in reservoir. In this study, we interpret the internal flow with installation and operation condition of CCCS based on CFD in reservoir. Design variables of CCCS is reservoir depth, stratification strength, distance of between CCCS and so on. Since reservoir depth and stratification strength in variables is depending on natural phenomenon, we evaluated current circulation effect by distance of CCCS and proposed the optimal design condition using CFD simulation. Flow and diffusion changes in water body was assessed by temperature and dye test. Changes in water floor temperature at 40m intervals was slowly descending over 37 hours. Dye diffusion simulation at 60m intervals, the radius of the spread between two devices were overlapped after 12 hours.

• International Journal of Automotive Technology
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• v.8 no.5
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• pp.615-622
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• 2007

In this study, a Coupled Computational Fluid Dynamics(CFD) and Finite Element Analysis(FEA) method are used to predict and evaluate the performance of an automotive shock absorber. Averaged Navier-Stokes equations are solved by the SIMPLE method and the RNG $k-\varepsilon$ is used to model turbulence. CFD analysis is carried out for different intake valve deflections and piston velocities. The force exerted on the valve in each valve deflection is obtained. The valve deflection-force relationship is investigated by the FEA method. The force exerted on the valve in each piston velocity is obtained with a combination of CFD and FEA results. Numerical results are compared with the experimental data and have shown agreement. Dependence of valve deflection as a function of piston velocity is investigated. Effects of hydraulic oil temperature change on valve behavior are also studied.

• Ocean Systems Engineering
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• v.12 no.2
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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.

• 한국전산유체공학회:학술대회논문집
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• 2009.04a
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• pp.9-18
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• 2009

This paper presents the state of the art of computational structures technology(CST) and comparison of two computational mechanics - CST and CFD, to the CFD engineers. Classical mechanics is based on the five classical axioms which describe the motion and behaviors of the continuum materials like solid structures and fluids. Computational structures technology uses the finite element method to solve the governing equation, whereas finite volume method is generally used in CFD. A few famous commercial structural analysis programs and DIAMOND/IPSAP will be introduced. DIAMOND/IPSAP is the efficient parallel structural analysis package developed by our research team. DIAMOND/IPSAP shows the better performance than the commercial structural analysis software not only in the parallel computing environments but also in a single computer.