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내부 에너지 소산에 대한 고차 수치 기법들의 검증 및 비교
권현진(H.J. Kwon),장세명(S.M. Chang) 한국전산유체공학회 2018 한국전산유체공학회지 Vol.23 No.1
In this paper, various TVD(total variation diminishing) and WENO(weighted essentially non-oscillatory) methods with high-order spatial accuracy are verified and compared for three examples of one-dimensional problems: convergence test for a linear sinusoidal wave, the nonlinear Sod’s shock tube, and shock-entropy wave interaction. Both limiter-based with second-order accuracy generally used in engineering society and WENO-based methods with fifth and seventh order accuracy are tested for the spatial reconstruction of Riemann problem approximated with Roe’s and HLL(Harten, Lax, and van Leer) scheme where the result is precisely verified with methods one by one for the characteristic-wise WENO as well as the original WENO flux splitting. The instant distribution of internal energy is focused on the flow region near the contact discontinuity and the entropy wave in this investigation, and the full capacity of numerical schemes is presented each other on the oscillation of internal energy.
완전 발달 난류 영역에서 면적과 유량비에 따른 T자형 분리관의 안정 길이 및 부차적 손실계수의 추정
권현진(H.J. Kwon),김미현(M.H. Kim),윤영준(Y.J. Yun),장세명(S.M. Chang),조용(Y. Cho) 한국전산유체공학회 2021 한국전산유체공학회지 Vol.26 No.4
In this research, we conducted numerical simulations of T-junction between Reynolds numbers 100,000~10,000,000 to get the minor(or dynamic) loss coefficients for the purpose of simplifying the three-dimensional CFD to one-dimensional analysis, forming the main pipe into the branch pipe of tees with varying area and flow rate ratio. As the ratio of flow rate changes, inflection points are found in the distribution of minor loss coefficients due to both separated and jetted flow. From the measurement of numerical results using the adequate parameters, this paper suggests the minimum stability length in branches of a pipe at each Reynolds number.
비정상 압축성 유동 해석에서 특성식 WENO 기법과 수치 점성 모델을 적용한 중앙차분법의 성능 및 비용 비교
권현진(H.J. Kwon),장세명(S.M. Chang) 한국전산유체공학회 2018 한국전산유체공학회지 Vol.23 No.2
In the computation of unsteady compressible fluid dynamics, unnecessary numerical oscillations can appear especially for the high-order spatial accuracy in the domain near the sharp discontinuities such as shock or slip line. The WENO(weighted essentially no oscillation) scheme can delete the oscillation of numerical dissipation error, and so can the central difference schemes with numerical viscosity, which have relatively low computational cost. The characteristics of conventional WENO and central difference schemes are compared with each other for a benchmark problem in this study, where LF(Lax-Friedrichs) and Garnier filters are used with ACM(Artificial Compression Method) switch.