Effect of rotating cylinder on the wake-wall interactions

• Published in: Ocean engineering 2017-07, Vol.139, p.275-286
• Main Authors: Shaafi, K., Naik, Sandeep N., Vengadesan, S.
• Format: Article
• Language: English
• Subjects: Boundary layer flow; IBM; Rotating cylinder; Vortex suppression; Vortex tracking
• ISSN: 0029-8018; 1873-5258
• DOI: 10.1016/j.oceaneng.2017.04.044

Laminar flow past a rotating cylinder near a plane wall is studied numerically using a second-order accurate immersed boundary method. The wake-wall interactions are investigated in detail, for different wall heights and varying rotational rates. Flow patterns are classified based on the wake structure and the effect of rotation on critical wall heights is discussed for both clockwise and counterclockwise rotation. For the configuration studied i.e. rotating cylinder above a bottom plane wall, counterclockwise rotation of cylinder favors the wake-wall interactions, while clockwise rotation influences in an adverse manner. In addition to conventional analysis, the evolution of the vortical structures in the wake region are examined using Lagrangian analysis of individual vortical structures. The diffusion of the positive vortex shed from the wall facing side of the cylinder is accelerated due to the influence of boundary layer with net negative vorticity. The wall augmented diffusion of positive cylinder vortices is compensated by the creation of secondary wall vortices from the bottom wall boundary layer. Counterclockwise rotation of cylinder increases the shear inside boundary layer resulting in more pronounced diffusion. •Wall proximity effect gives rise to three distinct vortex shedding regimes.•Rotation of cylinder increases the critical height of vortex suppression.•Dynamics of wake vortical structures were analyzed using vortex tracking approach Wake-wall boundary layer interactions creates secondary wall vortices.