Numerical simulation analysis of flow around near-wall rotating cylinder

Abstract

ObjectivesTo investigate the near-wall rotating cylindrical wake and hydrodynamic characteristics, flow around cylinder at typical gap ratios is investigated. MethodsA numerical simulation of flow around a near-wall rotating cylinder with different gap ratios (G/D = 0.2，0.8，1.4) and rotation rates at Reynolds number\begin{document}$Re = 200$\end{document} was carried out to compare the cylindrical wake and hydrodynamic characteristics at different gap ratios and rotation rates. ResultsThe results show that: For \begin{document}$G/D = 0.2$\end{document}, the cylindrical vortex shedding is significantly suppressed and the lift and drag force on the cylindrical surface remain steady. For \begin{document}$G/D = 0.8$\end{document} and \begin{document}$G/D = 1.4$\end{document}, at low rotation rates, the "wake vortex" is shed and is similar to the 2S pattern, with sinusoidal periodic fluctuations in the lift and drag coefficients and small amplitude; at higher positive rotation rates, the cylindrical wake pattern is the stable D pattern with no vortex shedding (changing from D+ to D− pattern as the rotation rate increases), the "wake vortex layer" is separated from the "wall vortex layer", the "wall vortex" is shed multi-periodically, the lift and drag coefficients are fluctuating multi-periodically and the amplitude is increasing significantly; at higher reverse rotation rates, the cylindrical surface is wrapped by a positive boundary layer, with no vortex shedding and no fluctuations in lift and drag. ConclusionsThe results can provide a reference for the development of high efficient flow control technology.

Keywords

• flow around cylinder
• rotating
• near-wall cylinder
• lift and drag force
• vortex layer separation