Numerical study on drag reduction and wake modification for the flows over a hydrofoil in presence of surface heterogeneity. (January 2022)

• Record Type: Journal Article
• Authors: Kouser, Taiba; Xiong, Yongliang; Yang, Dan; Peng, Sai
• Is Part Of: Advances in mechanical engineering. Volume 14:Number 1(2022)
• Publication Date: 2022-01
• Subjects: Superhydrophobic surface -- no-slip and shear-free boundary -- angles of attack -- drag reduction; Mechanical engineering -- Periodicals; 621.05
• DOI: 10.1177/16878140221075306
• Languages: English
• ISSNs: 1687-8132

Abstract

In this article, direct numerical simulations of flow around NACA0012 hydrofoil with superhydrophobic surface (SHS) is presented. Surface heterogeneity takes into account by periodic no-slip and shear-free grates on the surface. The study is conducted for a range of0 o − 25 o degree angles of attack and at fixed Reynolds number ( Re ) 1000. SHS leads to effective Navier slip on the hydrofoil surface and corresponding changes in velocity profile. Bubble separation delays for higher gas-fraction ( G.F ), and minimizes the vortex shedding effects. As a result, flow remains two-dimensional (2D) for higher angles of attack as compared to flow over three-dimensional (3D) hydrofoil with no-slip boundary. Both the drag reduction and enhancement of lift force are observed. Maximum lift are observed atα = 13 o, while the drag force continues to decrease with the gradual increase in angle of attack and patterned micro-grates fraction. Mode C with smaller wavelength is observed atα = 15 o . Furthermore, increase in gas-fraction leads to increase in slip length which thickens the boundary layer and mimics the vorticity implies drag reduction. Thus, replacement of the no-slip surfaces by superhydrophobic surfaces can be treated as a promising drag reduction technology.