http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
초음속 기저부 유동에서 ${\kappa}-{\varepsilon}$ 난류 모델에 대한 와점성 계수의 영향
박수형,사정환,김지웅,권장혁,김창주,Park, Soo-Hyung,Sa, Jeong-Hwan,Kim, Jee-Woong,Kwon, Jang-Hyuk,Kim, Chang-Joo 한국전산유체공학회 2008 한국전산유체공학회지 Vol.13 No.3
A supersonic base flow is computed to investigate the effect of the eddy viscosity coefficient to the linear ${\kappa}-{\varepsilon}$ turbulence models. Slight modifications to the eddy viscosity coefficient, which are based on the realizability condition, are given to the Launder-Sharma turbulence model so that present models satisfy the realizability condition. Numerical results for supersonic base flow show that turbulence models with the weaky-nonlinear eddy viscosity coefficient can lead to reasonable enhancements in the prediction of the velocity and turbulent kinetic energy profiles.
박수형(Soo Hyung Park),성춘호(Chun-ho Sung),권장혁(Jang Hyuk Kwon),이승수(Seungsoo Lee) 한국전산유체공학회 2002 한국전산유체공학회지 Vol.7 No.4
An efficient implicit multigrid method is presented for the Navier- Stokes and k-ω turbulence equations. Freezing and limiting strategies are applied to improve the robustness and convergence of the multigrid method. The eddy viscosity and strongly nonlinear production terms of turbulence are frozen in the coarser grids by passing down the values without update of them. The turbulence equations together with the Navier-Stokes equations, however, are consecutively solved on the coarser grids in a loosely coupled fashion. A simple limit for k is also introduced lo circumvent slow down of convergence. Numerical results for the unseparated and separated transonic airfoil flows show that all computations converge well without any robustness problem and the computing time is reduced to a factor of about 3 by the present multigrid method.
HLLE+와 LU-AF를 이용한 극초음속 화학적 비평형 유동장 해석
박수형(Soo-Hyung Park),권장혁(Tang Hyuk Kwon) 한국전산유체공학회 2000 한국전산유체공학회지 Vol.5 No.2
A robust Navier-Stokes code has been developed to efficiently predict hypersonic flows in chemical nonequilibrium. The HLLE + flux discretization scheme is used to improve accuracy and robustness of hypersonic flow analysis. An efficient LU approximate factorization method is also used to solve the flow equations and species continuity equations in fully coupled fashion to implicitly treat stiff source terms of chemical reactions. The HLLE+ scheme shows lower grid dependency for the wall heating rates than other schemes. The developed code has been used to compute chemical nonequilibrium air flow through expanding hypersonic nozzle and past two and three dimensional blunt-nosed bodies. The results are in good agreement with existing numerical and experimental results.
박수형(Soo Hyung Park),김윤식(Yoonsik Kim),권장혁(Jang Hyuk Kwon) 한국전산유체공학회 2001 한국전산유체공학회 학술대회논문집 Vol.2001 No.-
A dual-time stepping algorithm combined with a parallelized multigrid DADI method is presented to predict the dynamic damping coefficients. The Basic Firmer model is chosen to validate the prediction capability of the present unsteady Euler method. The linearity of the pitch- and roll-damping coefficients is shown in the low angular rates and the interesting large drop and stiff increment in transonic region for roll-damping coefficients are explained in detail. Through the analysis for the pressure distributions at Mach number 1.0 to 1.2. the sudden drop results from the normal shock and the stiff increment of roll-damping reflects the transition of the normal shock to the oblique shock. The results also show that the Euler equations can give the damping coefficients with a comparable accuracy.