국내 최대 기계 및 로봇 연구정보

기술보고서

기술보고서 게시판 내용
타이틀	Comparison of Effectiveness of Four Open Boundary Conditions for Incompressible Unbounded Flows
저자	Shigeki Hatayama
Keyword	Leith type 3D upwind scheme, open boundary condition; Sommerfeld radiation condition; backward-facing step flow; blunt based body flow; rectangular cylinder obstacle flow
URL	http://send.nal.go.jp/send/jpn/dlpdf.php3/naltr0001374t.pdf?id=NALTR0001374T
보고서번호	NAL TR-1374T
발행년도	1999.01
출처	NAL (National Aerospace Laboratory of Japan)
ABSTRACT	Four open boundary conditions for incompressible unbounded flows are evaluated in the framework of the Leith type third-order upwind scheme (QUICKEST scheme), and the effectiveness of each is compared by two means: the difference of flows among open boundary conditions, and between short and long open boundaries. Three test problems used for the open boundary condition evaluation are the backward-facing step flow, the blunt based body flow and the rectangular cylinder obstacle flow in a channel. The investigated open boundary conditions are (1) the one first used by Thoman and Szewczyk (1966), (2) the one proposed by Mehta and Lavan (1975), (3) the Sommerfeld radiation condition first used by Orlanski (1976), and (4) the Sommerfeld radiation condition used by Bottaro (1990) and Kobayashi et al. (1993). In (3), Orlanski proposed a method which numerically evaluates the phase speed at the closest interior points every time. In (4), Bottaro and Kobayashi et al. proposed taking the mean channel velocity as the phase speed. The author proposes taking the uniform inlet velocity as the phase speed. As the conclusion, we show that (4) is the optimum open boundary condition of the four conditions. The effects of several values of constant phase speed are shown.