Ndebele, Bright BGledhill, IMA2023-10-132023-10-132023-09Ndebele, B.B. & Gledhill, I. 2023. Two dimensional vortex shedding from a rotating cluster of cylinders. <i>Journal of Applied Fluid Mechanics, 16(11).</i> http://hdl.handle.net/10204/131511735-35721735-3645DOI: 10.47176/JAFM.16.11.1773http://hdl.handle.net/10204/13151The dynamics of two-dimensional vortex shedding from a rotating cluster of three cylinders was investigated using Computational Fluid Dynamics (CFD) and Dynamic Mode Decomposition (DMD). The cluster was formed from three circles with equal diameters in mutual contact and allowed to rotate about an axis passing through the cluster centroid. While immersed in an incompressible fluid with Reynolds number of 100, the cluster was allowed to rotate at non-dimensionalised rotation rates (Ω) between 0 and 1. The rotation rates were non-dimensionalised using the free-stream velocity and the cluster characteristic diameter, the latter being equal to the diameter of the circle circumscribing the cluster. CFD simulations were performed using StarCCM+. Dynamic Mode Decomposition based on the two-dimensional vorticity field was used to decompose the field into its fundamental mode-shapes. It was then possible to relate the mode-shapes to lift and drag. Transverse and longitudinal mode-shapes corresponded to lift and drag, respectively. Lift–drag polars showed a more complex pattern dependent on Ω in which the flow fields could be classified into three regimes: Ω less than 0.3, greater than 0.5, and between 0.3 and 0.5. In general, the polars formed open curves in contrast to those of static cylinders, which were closed. However, some cases, such as Ω = 0.01, 0.22, and 0.28, formed closed curves. Whether a lift-drag polar was closed or open was deduced to be determined by the ratio of Strouhal numbers calculated using lift and drag time series, with closed curves forming when the ratio is an integer.FulltextenComputational Fluid DynamicsDynamic Mode DecompositionRotating cylindersVortex sheddingArticleNdebele, B. B., & Gledhill, I. (2023). Two dimensional vortex shedding from a rotating cluster of cylinders. <i>Journal of Applied Fluid Mechanics, 16(11)</i>, http://hdl.handle.net/10204/13151Ndebele, Bright B, and IMA Gledhill "Two dimensional vortex shedding from a rotating cluster of cylinders." <i>Journal of Applied Fluid Mechanics, 16(11)</i> (2023) http://hdl.handle.net/10204/13151Ndebele BB, Gledhill I. Two dimensional vortex shedding from a rotating cluster of cylinders. Journal of Applied Fluid Mechanics, 16(11). 2023; http://hdl.handle.net/10204/13151.TY - Article AU - Ndebele, Bright B AU - Gledhill, IMA AB - The dynamics of two-dimensional vortex shedding from a rotating cluster of three cylinders was investigated using Computational Fluid Dynamics (CFD) and Dynamic Mode Decomposition (DMD). The cluster was formed from three circles with equal diameters in mutual contact and allowed to rotate about an axis passing through the cluster centroid. While immersed in an incompressible fluid with Reynolds number of 100, the cluster was allowed to rotate at non-dimensionalised rotation rates (Ω) between 0 and 1. The rotation rates were non-dimensionalised using the free-stream velocity and the cluster characteristic diameter, the latter being equal to the diameter of the circle circumscribing the cluster. CFD simulations were performed using StarCCM+. Dynamic Mode Decomposition based on the two-dimensional vorticity field was used to decompose the field into its fundamental mode-shapes. It was then possible to relate the mode-shapes to lift and drag. Transverse and longitudinal mode-shapes corresponded to lift and drag, respectively. Lift–drag polars showed a more complex pattern dependent on Ω in which the flow fields could be classified into three regimes: Ω less than 0.3, greater than 0.5, and between 0.3 and 0.5. In general, the polars formed open curves in contrast to those of static cylinders, which were closed. However, some cases, such as Ω = 0.01, 0.22, and 0.28, formed closed curves. Whether a lift-drag polar was closed or open was deduced to be determined by the ratio of Strouhal numbers calculated using lift and drag time series, with closed curves forming when the ratio is an integer. DA - 2023-09 DB - ResearchSpace DP - CSIR J1 - Journal of Applied Fluid Mechanics, 16(11) KW - Computational Fluid Dynamics KW - Dynamic Mode Decomposition KW - Rotating cylinders KW - Vortex shedding LK - https://researchspace.csir.co.za PY - 2023 SM - 1735-3572 SM - 1735-3645 T1 - Two dimensional vortex shedding from a rotating cluster of cylinders TI - Two dimensional vortex shedding from a rotating cluster of cylinders UR - http://hdl.handle.net/10204/13151 ER -27142