개선된 PANS 난류 모델 기반 높은 레이놀즈수 난류 유동 수치 모사: 회전율이 고정된 회전실린더 (COMPUTATIONAL SIMULATION OF TURBULENT FLOW USING AN IMPROVED PANS MODEL AT HIGH REYNOLDS NUMBERS: ROTATING CYLINDER WITH A FIXED SPIN RATIO)

서지정보

· 발행기관 : 한국전산유체공학회
· 수록지 정보 : 한국전산유체공학회지 / 29권 / 4호 / 117 ~ 127페이지
· 저자명 : 김효주, 석우찬, 이상봉

초록

Flow around a rotating cylinder was analyzed using an improved Partially Averaged Navier-Stokes(PANS) model within a Reynolds number(Re) range of  to  . To observe the flow characteristics of the rotating cylinder over a wide range of Reynolds numbers, the rotation rate, which represents the ratio of rotational flow to free flow, was fixed at 1. Compared to the fixed cylinder where a sharp drop in the drag coefficient is observed, the rotating cylinder showed a monotonic decrease in both drag and lift coefficients as the Reynolds number increased on a logarithmic scale. With the application of counter-clockwise rotation, the upper surface of the cylinder experienced a local deceleration flow due to the flow opposing the free stream. This caused the separation point to move upstream compared to that of the fixed cylinder, directing the flow relatively outward from the cylinder. Conversely, on the lower surface of the cylinder, an additional flow in the same direction as the free stream resulted in partial acceleration, delaying the separation point further downstream and causing the flow to converge inward toward the cylinder. With increasing Re, the separation point on the lower surface remained nearly constant, whereas that on the upper surface gradually moved downstream, with the flow direction increasingly converging inward. Therefore, the vortices formed directly behind the cylinder transitioned from asymmetric flow to a nearly symmetric flow pattern.
However, further downstream, deflection is still observed despite the increase in Re.

영어초록

Flow around a rotating cylinder was analyzed using an improved Partially Averaged Navier-Stokes(PANS) model within a Reynolds number(Re) range of  to  . To observe the flow characteristics of the rotating cylinder over a wide range of Reynolds numbers, the rotation rate, which represents the ratio of rotational flow to free flow, was fixed at 1. Compared to the fixed cylinder where a sharp drop in the drag coefficient is observed, the rotating cylinder showed a monotonic decrease in both drag and lift coefficients as the Reynolds number increased on a logarithmic scale. With the application of counter-clockwise rotation, the upper surface of the cylinder experienced a local deceleration flow due to the flow opposing the free stream. This caused the separation point to move upstream compared to that of the fixed cylinder, directing the flow relatively outward from the cylinder. Conversely, on the lower surface of the cylinder, an additional flow in the same direction as the free stream resulted in partial acceleration, delaying the separation point further downstream and causing the flow to converge inward toward the cylinder. With increasing Re, the separation point on the lower surface remained nearly constant, whereas that on the upper surface gradually moved downstream, with the flow direction increasingly converging inward. Therefore, the vortices formed directly behind the cylinder transitioned from asymmetric flow to a nearly symmetric flow pattern.
However, further downstream, deflection is still observed despite the increase in Re.

참고자료

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