Application of Multigrid Method for Computing Hypersonic Flows

This paper presents an efficient and robust multigrid method for computing inviscid and viscous high-speed steady-state reactive flows. Curve fitted data in NASA Reference Publication 1811, 1260 are used to calculate equilibrium properties. Nonequilibrium flows are calculated using 5-species and 2-temperature air model. A 5-stage Runge-Kutta method and an LU-SGS method are adopted for time integration. When a 5-stage Runge-Kutta method is used, the chemical source terms are treated in a point-implicit manner. In order to overcome stabiEty problem in applying multigrid method to high-speed reactive flow calculation, an improved damped prolongation and a new implicit residual smoothing are proposed. This method is applied to computing hypersonic equilibrium and nonequilibrium flows over a half-cylinder at a flight condition corresponding to M=10 and 60km altitude. Results indicate the robustness of proposed methods and good multigrid speed-ups in both equilibrium and nonequilibrium test cases.화학반응을 동반한 극초음속 유동의 효율적인 계산을 위한 강건한 다중격자기법이 본 논문에서 연구되었다. 평형유동 계산을 위하여 NA5A RP-1811과 RP-1260의 curve-fit data를 이용하였으며 비평형유동 계산은 5-species, 2-temperature 모델을 이용하였다. 시간적분은 외재적 방법인 5단계 Runge-Kutta와 내재적 방법인 LU-SGS를 사용하였으며 각 기법의 계산 효율을 비교하였다 다중격자기법을 극초음속 유통에 적용할 경우 생기는 불안정성을 해결하기 위하여 damped prolongation과 residual smoothing을 새로이 개발하였고 이를 마하수 10의 half-cylinder 문제에 적용하였다.OAIID:oai:osos.snu.ac.kr:snu2001-01/102/0000004648/3SEQ:3PERF_CD:SNU2001-01EVAL_ITEM_CD:102USER_ID:0000004648ADJUST_YN:NEMP_ID:A001138DEPT_CD:446CITE_RATE:0FILENAME:다중격자기법을_적용한_극초음속_유동장_계산.pdfDEPT_NM:기계항공공학부EMAIL:chongam@snu.ac.krCONFIRM: