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이경세(Kyung Seh Lee),백제현(Je Hyun Baek) 한국유체기계학회 2006 유체기계 연구개발 발표회 논문집 Vol.- No.-
A large eddy simulation with explicit filters on unstructured mesh is presented. The flow filed is semi-implicitly marched by a fractional step method. Spatial discretization of the solver is designed to guarantee the second order accuracy. Two explicit filters are adopted for reducing the aliasing error of the nonlinear convective term and measuring the level of subgrid scale velocity fluctuation, respectively. The filters are linearity-preserving and have second order commutation error. The developed subgrid scale model is basically eddy viscosity model which depends on the explicitly filtered fields and needs no additional ad hoc wall treatment, such as van Driest damping function. As a validation problem, the flows around a sphere at several Reynolds numbers, including laminar and turbulent regimes, are calculated and compared to experimental data and numerical results in the literature.
Development of a Lift Correction Method for Shear Flow Effects in BEM Theory
이경세(Lee, Kyung Seh),정진화(Jung, Chin Hwa),박현철(Park, Hyun Chul) 한국신재생에너지학회 2011 한국신재생에너지학회 학술대회논문집 Vol.2011 No.05
In this study, the effects of shear flows around a 2-dimensional airfoil, S809 on its aerodynamic characteristics were analyzed by CFD simulations. Various parameters including reference inflow velocity, shear rate, angle of attack, and cord length of the airfoil were examined. From the simulation results, several important characteristics were found. Shear rate in a flow makes some changes in the lift coefficient depending on its sign and magnitude but angle of attack does not have a distinguishable influence. Cord length and reference inflow also cause proportional and inversely proportional changes in lift coefficient, respectively. We adopted an analytic expression for the lift coefficient from the thin airfoil theory and proposed a modified form applicable to the traditional load analysis procedure based on the blade element momentum theory. Some preliminary results applied to an well known load simulation software, FAST, are presented.