Interfacial properties of mechanical elements on vortex shedding: Roughness and hydrophilicity

A Kármán vortex street, a fundamental yet fascinating phenomenon in fluid dynamics and nature, has attracted scientists for centuries. Despite numerous studies thoroughly scrutinizing the Kármán vortex street both theoretically and experimentally, few have explored the influence of material interfacial properties on vortex shedding. In this paper, we investigate the effect of the material roughness and hydrophilicity on the lift force and shedding areas induced by vortex shedding. A conventional stationary cylinder coated with various materials is used as a bluff body to generate vortex streets, with an array of piezoelectric sensors measuring the lift force. The roughness and hydrophilicity of five representative materials are characterized. A modified vortex shedding model, computational fluid dynamics simulations, and experiments are used to analyze the vortex shedding with different interface materials. It is found that the surface roughness and hydrophilicity synergistically affect the frequency and amplitude of the lift force, as well as the onset position of the vortex shedding. This study provides a new insight into the suppression or utilization of the Kármán vortex street.