• 한국연소학회:학술대회논문집
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• 한국연소학회 2012년도 제45회 KOSCO SYMPOSIUM 초록집
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• pp.141-143
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• 2012

The present study is aiming at numerically analyze the soot formation processes coupled with gas reaction mechanism in turbulent non-premixed and partially premixed flames. In order to realistically represent turbulence-chemistry interactions with detailed chemical kinetics and soot formation behaviour related to the turbulent non-premixed and partially premixed flames, the transient flamelet[1] and flamelet based level-set approach[2] are coupled with soot formation based on the two equation model [3] and DQMOM (Direct Quadrature Method of Moment)[4].

• Journal of the Optical Society of Korea
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• 제19권1호
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• pp.45-54
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• 2015

In this study, a novel parallel wavefront correction system architecture is proposed, and a model-based tabu search (MBTS) algorithm is introduced for this new system to compensate wavefront aberration caused by atmospheric turbulence in a free-space optical (FSO) communication system. The algorithm flowchart is presented, and a simple hypothetical design for the parallel correction system with multiple adaptive optical (AO) subsystems is given. The simulated performance of MBTS for an AO-FSO system is analyzed. The results indicate that the proposed algorithm offers better performance in wavefront aberration compensation, coupling efficiency, and convergence speed than a stochastic parallel gradient descent (SPGD) algorithm.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 2008년도 제30회 춘계학술대회논문집
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• pp.343-346
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• 2008

초음속 주 유동내 연료의 수직분사 유동장에 대한 비정상 3차원 수치해석이 DES 난류 모델을 이용하여 수행되었다. 해석 결과는 시간에 따른 에디의 위치 및 에디 생성 빈도에 대하여 실험과 비교되었다. DES 난류 모델은 에디의 대류 특성을 비교적 정확하게 모사하고 있는 반면에 에디 생성 빈도는 다소 과대 예측하고 있다.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년도 학술대회
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• pp.97-103
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• 2008

Unsteady three-dimensional flowfields generated by transverse fuel injection into a supersonic mainstream are simulated with a DES turbulence model. Comparisons are made with experimental results in term of the temporal eddy position and eddy formation frequency. The vorticity field around the jet exit is also analyzed to understand the formation mechanism of the jet vortical structures. Results indicate that the DES model correctly predicts the convection characteristics of the large scale eddies. However, it is also observed that the numerical results slightly overpredict the eddy formation frequency. The jet vortical structures are developed from the competing vortices in the recirculation region of upstream boundary.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집B
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• pp.603-608
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• 2000

The characteristics of laminar and turbulent slot impinging jet flows are examined using segregated FEM with SUPG. Turbulent flows are modeled using $Wilcox^{(1)}$ $k-\;{\omega}$ turbulence model. The results are validated by comparing with velocity field of the existing experimental data. The distance of the target plate from the nozzle varies between 2, 4 and 5 times the slot jet width. Present study shows that the $k-\;{\omega}$ model gives results which agree well with the existing experimental data. In turbulence flows, the velocity profile of present calculation is more accurate than the existing numerical calculations. In laminar flows, We found tertiary vortex which was not found in the previous numerical study by M. $chen^{(6)}$ et al due to the numerical difference.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 춘계학술대회
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• pp.1980-1985
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• 2003

Two nonlinear ${\kappa}-{\epsilon}$ models with the wall function method are applied to the fully developed turbulent flow in a square duct. Typical predicted quantities such as axial and secondary velocities, turbulent kinetic energy and Reynolds stresses are compared in details both qualitatively and quantitatively with each other. A nonlinear ${\kappa}-{\epsilon}$ model with the wall function method capable of predicting accurately duct flows involving turbulence-driven secondary motion is presented in the present paper. The nonlinear ${\kappa}-{\epsilon}$ model adopted in a commercial code is found to be unable to predict accurately duct flows with the prediction level of secondary flows one order less than that of the experiment.

• 한국전산유체공학회:학술대회논문집
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• 한국전산유체공학회 2008년 추계학술대회논문집
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• pp.97-103
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• 2008

Unsteady three-dimensional flowfields generated by transverse fuel injection into a supersonic mainstream are simulated with a DES turbulence model. Comparisons are made with experimental results in term of the temporal eddy position and eddy formation frequency. The vorticity field around the jet exit is also analyzed to understand the formation mechanism of the jet vortical structures. Results indicate that the DES model correctly predicts the convection characteristics of the large scale eddies. However, it is also observed that the numerical results slightly overpredict the eddy formation frequency. The jet vortical structures are developed from the competing vortices in the recirculation region of upstream boundary.

• 대한기계학회논문집
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• 제12권4호
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• pp.865-875
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• 1988

본 연구에서는 부정숙 등에 의한 실험결과를 토대로 하여, 단이 진 2차원 벽 면분류에 대한 수치해석으로 표준 K-.epsilon.모델과 LRM 그리고 PAM을 적용하고, upwind 및 skew-upwind scheme을 적용하여 그 결과를 검토하고자 한다.

• 대한기계학회논문집B
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• 제27권6호
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• pp.821-827
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• 2003

Fully developed turbulent flow in a square duct is numerically predicted with two nonlinear low-Reynolds-number ${\kappa}-{\varepsilon}$ models. Typical predicted quantities such as axial and secondary velocities, turbulent kinetic energy and Reynolds stresses are compared in detail with each other. It is found that the nonlinear low-Reynolds-number ${\kappa}-{\varepsilon}$ model adopted in a commercial code is unable to predict accurately duct flows involving turbulence-driven secondary motion with the prediction level of secondary flows one order less than that of the experiment.

• 한국전산유체공학회지
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• 제8권1호
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• pp.23-29
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• 2003

Two nonlinear κ-ε models with the wall function method are applied to the fully developed turbulent flow in a square duct. Typical predicted quantities such as axial and secondary velocities, turbulent kinetic energy and Reynolds stresses are compared in details both qualitatively and quantitatively with each other. A nonlinear κ-ε model with the wall function method capable of predicting accurately duct flows involving turbulence-driven secondary motion is presented in the present paper. The nonlinear κ-ε model of Shih et al.[1] adopted in a commercial code is found to be unable to predict accurately duct flows with the prediction level of secondary flows one order less than that of the experiment.