http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
2차원 천이 영역 유동 해석을 위한 비정렬 격자 기반의 Gas-Kinetic BGK 기법
양태호(T. H. Yang),권오준(O. J. Kwon) 한국전산유체공학회 2014 한국전산유체공학회 학술대회논문집 Vol.2014 No.5
In the present study, 2-D gas-kinetic flow solver on unstructured meshes was developed for flows from continuum to transitional regimes. The gas-kinetic BGK scheme is based on numerical solutions of the BGK simplification of the Boltzmann transport equation. In the initial reconstruction, the unstructured version of the linear interpolation is applied to compute left and right states along a cell interface. In the gas evolution step, the numerical fluxes are computed from the evaluation of the time-dependent gas distribution function around a cell interface. Two-dimensional compressible flow calculations were performed to verify the accuracy and robustness of the current gas-kinetic approach. Gas-kinetic BGK scheme was successfully applied to two-dimensional steady and unsteady flow simulations with strong contact discontinuities. Exemplary hypersonic viscous simulations have been conducted to analyze the performances of the gas-kinetic scheme. The computed results show fair agreement with other standard particle-based approaches for both continuum part and transitional part.
유한체적법 기반의 격자 볼츠만 해석 기법을 이용한 이차원 압축성 점성 유동 해석
양태호(T.H. Yang),권오준(O.J. Kwon) 한국전산유체공학회 2018 한국전산유체공학회지 Vol.23 No.2
This paper presents a finite-volume based lattice Boltzmann method for simulation of full compressible flows with flexible Prandtl number. The equilibrium distribution function is replaced with circular function where all mass, momentum, and energy is equally distributed along a circle. Two different density distribution functions are newly introduced to develop lattice Boltzmann model for compressible viscous flows. The equilibrium distribution function for the evolution equations can be derived from the integration of the Lagrangian interpolation polynomial, which depends on the configurations of the lattice model in the velocity phase space. Two-dimensional compressible flows in a shock tube were investigated to verify the accuracy of the current lattice Boltzmann method. The lattice Boltzmann method based on circular function was successfully adopted to two-dimenstional unsteady simulations with strong contact discontinuities. The present lattice Boltzmann code is applied to the subsonic laminar flow over an NACA0012 airfoil, and the computed results show fair agreement with the Navier-Stokes solution. The hypersonic flow passing through a cylinder is selected as a test case to verify the performances of the current lattice Boltzmann approach. The present solver gives a reasonable agreement with the continuum-based simulation results for flows including detached normal shock wave near the leading edge. Our results imply that the replacement of the Maxwellian distribution function with circular function may be the suitable approach for the evaluation of compressible viscous flows.
비정렬 격자계에서 연속체 및 천이 영역 유동 해석을 위한 2차원 Gas-Kinetic BGK 해석자 개발
양태호(T.H. Yang),권오준(O.J. Kwon) 한국전산유체공학회 2014 한국전산유체공학회지 Vol.19 No.2
In the present study, 2-D gas-kinetic flow solver on unstructured meshes was developed for flows from continuum to transitional regimes. The gas-kinetic BGK scheme is based on numerical solutions of the BGK simplification of the Boltzmann transport equation. In the initial reconstruction, the unstructured version of the linear interpolation is applied to compute left and right states along a cell interface. In the gas evolution step, the numerical fluxes are computed from the evaluation of the time-dependent gas distribution function around a cell interface. Two-dimensional compressible flow calculations were performed to verify the accuracy and robustness of the current gas-kinetic approach. Gas-kinetic BGK scheme was successfully applied to two-dimensional steady and unsteady flow simulations with strong contact discontinuities. Exemplary hypersonic viscous simulations have been conducted to analyze the performances of the gas-kinetic scheme. The computed results show fair agreement with other standard particle-based approaches for both continuum part and transitional part.
외부 오염물 증착에 의한 풍력 터빈 날개 단면의 공력 성능 저하 예측
양태호(T.H. Yang),최재훈(J.H. Choi),유동옥(D.O. Yu),권오준(O.J. Kwon) 한국전산유체공학회 2013 한국전산유체공학회지 Vol.18 No.1
In the present study, the effects of contaminant accumulation and surface roughness on the aerodynamic performance of wind turbine blade sections were numerically investigated by using a flow solver based on unstructured meshes. The turbulent flow over the rough surface was modeled by a modified κ-ω SST turbulence model. The calculations were made for the NREL S809 airfoil with varying contaminant sizes and positions at several angles of attack. It was found that as the contaminant size increases, the degradation of the airfoil performance becomes more significant, and this trend is further amplified near the stall condition. When the contaminant is located at the upper surface near the leading edge, the loss in the aerodynamic performance of the blade section becomes more critical. It was also found that the surface roughness leads to a significant reduction of lift, in addition to increased drag.
충돌 속도에 따른 실리콘 충격 프로그래머의 유효 탄성 계수 예측에 관한 연구
양태호 ( T H Yang ),이영신 ( Y S Lee ),김윤재 ( Y J Kim ),김태형 ( T H Kim ),설창원 ( C W Shul ),양명석 ( M S Yang ),안채헌 ( C H An ),이규섭 ( G S Lee ) 한국안전학회(구 한국산업안전학회) 2014 한국안전학회지 Vol.29 No.1
The silicon as the hyper-elastic material was used to design the shock programmer and dynamic characteristic of the shock programmer was studied. The shock programmer was a structure part that was mounted between the impactor and the test bed. The role of the shock programmer was to generate the acceleration time history by the objective of various impact tests. The effective elastic modulus of the silicon was varied under the velocity of the impactor. The effective elastic modulus of the silicon was estimated by the comparison with results between test and simulation