Effects of wavelength on vortex structure and turbulence kinetic energy transfer of flow over undulated cylinders

Passive flow control research is commonly utilized to provide desirable drag and oscillating lift reduction across a range of engineering applications. This explores the spanwise undulated cylinder inspired by seal whiskers, shown reduce forces when compared smooth cylinders. Although fluid over this unique complex geometry has been documented experimentally computationally, investigations surrounding geometric modifications undulation topography have limited, mechanisms which force induced not fully examined. Five wavelength variations model are simulated at Reynolds number $\Rey=250$ with results from elliptical cylinder. Vortex structures turbulence kinetic energy (TKE) transfer in wake analyzed explain how affects reduction. Modifications generate variety patterns including alternating vortex rollers hairpin vortices. Maximum observed wavelengths that large enough allow vortices develop without intersecting each other small prevent generation additional structures. The differences modify magnitude location TKE production dissipation due changes mean fluctuating strain. Decreased increased near result overall lower reduced body forces. Understanding physics linking will guide appropriate parameter selection bio-inspired design