직육면체를 지나는 층류 유동

다국어 초록 (Multilingual Abstract)

Laminar flows over a cube and a cuboid (cube extended in the streamwise direction) are numerically investigated for the Reynolds numbers between 50 and 350. First, vortical structures behind a cube and lift characteristics are scrutinized in order to understand the variation in vortex shedding characteristics with respect to the Reynolds number. As the Reynolds number increases, the flow over a cube experiences the steady planar-symmetric, unsteady planar-symmetric, and unsteady asymmetric flows. Similar to the sphere wake, the planar-symmetric flow over a cube can be divided into two different regimes: single-frequency regime and multiple-frequency regime. The former has a single frequency due to regular shedding of vortices with the same strength in time, while the latter has multiple frequency components due to temporal variation in the strength of shed vortices. Second, the effect of the length-to-height ratio of the cuboid on the flow characteristics is investigated for the Reynolds number of 270, at which planar-symmetric vortex shedding takes place behind a cube. With the ratio smaller than one, the flow over the cuboid becomes unsteady asymmetric flow, whereas it becomes steady flow for the ratios greater than one. With increasing the ratio, the drag coefficient first decreases and then increases. This feature is related to the flow reattachment on the side faces of the cuboid.

참고문헌 (Reference)

1 김동주, "구 주위의 비정상 면대칭 및 비대칭 유동의 특성" 1009-1012, 2006

2 Yun, G., "Vortical structures behind a sphere at subcritical Reynolds numbers" 18 : 015102-1-14, 2006

3 Williamson, C.H.K., "Vortex dynamics in the cylinder wake" 28 : 477-539, 1996

4 Saha, A.K., "Three-dimensional numerical simulation of the transition of flow past a cube" 16 : 1630-1646, 2004

5 Mittal, R., "Planar symmetry in the unsteady wake of a sphere" 37 (37): 388-390, 1999

6 Jeong, J., "On the identification of a vortex" 285 : 69-94, 1995

7 Strykowski, P.J., "On the formation and suppression of vortex shedding at low Reynolds numbers" 218 : 71-107, 1990

8 Kim, D., "Laminar flow past a sphere rotating in the streamwise direction" 461 : 365-386, 2002

9 Johnson, T.A., "Flow past a sphere up to a Reynolds number of 300" 378 : 19-70, 1999

10 Kwon, K., "Control of laminar vortex shedding behind a circular cylinder using splitter plates" 8 : 479-486, 1996

11 Kim, J., "An immersed boundary finite-volume method for simulations of flow in complex geometries" 171 : 132-150, 2001

12 Raul, R., "An application of the vorticity-vector potential method to laminar cube flow" 10 : 875-888, 1990

13 Raul, R., "An application of the vorticity-vector potential method to laminar cube flow" 10 : 875-888, 1990

14 Sakamoto, H., "A study on vortex shedding from spheres in a uniform flow" 112 : 386-392, 1990