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摘要
A Fourier-Chebyshev spectral collocation method is used to compute the flow past a steadily rotating sphere subjected to a uniform cross flow. The simulations are performed at Reynolds numbers Re = 100, 250 and 300, where the Reynolds number is based on freestream velocity and sphere diameter. These Reynolds numbers cover three different flow regimes for a stationary sphere, from steady axisymmetric, steady planar-symmetric to unsteady planar-symmetric. The effect of varying the rotation axis angle, alpha, on the laminar flow structures and time-averaged hydrodynamic forces is investigated over a range of non-dimensional rotation rates, Omega(center dot). This study reveals the time-averaged flight path of a solid rotating particle. At Re = 100, the flow is always steady. The near-wake projected streamline patterns and pressure coefficient contours are topologically similar at alpha = 0 independent of the range of Omega(center dot) considered. As alpha increases, the near-wake recirculation bubble is either suppressed or shifted and thus affects the pressure recovery behind the sphere. This in turn affects both the drag and lift coefficients, C(D) and C. For all a considered. C(D) and C(L) increase as alpha increases and the increment is more pronounced at higher Si. At Re = 250 and 300, calculations show both steady and unsteady wake structures. The state of the wake structures depends strongly on alpha and Omega(center dot). However, the time-averaged flow fields are qualitatively similar to Re = 100. As a result, the time averaged drag and lift coefficients, C(D) and Q follow the same trend as at Re = 100. The increase in Re dramatically reduce the C(D) compared to the same Omega(center dot) and alpha at Re = 100. C(L) shows a more complicated behaviour as Re increases.
- 出版日期2010-10
- 单位CSIRO
