It is known that the presence of air pockets on the SHS facilitates the liquid-slip phenomenon over the surface and subsequent reduction of wall shear stress. The slip length on SHSs is, unfortunately, negatively coupled with the stability of the air pocket, limiting the applicability of the technology. The focus of this study is to investigate the feasibility of using SHSs covered with hierarchical texture to simultaneously achieve large drag reduction and robustness against pressure perturbation. The core hypothesis is that hierarchically textured SHSs can increase the fraction of air without compromising the robustness of the water-air interface, which leads to robust drag reduction. The role of micro and nano scales is studied independently to understand the contribution of each scale towards the drag reduction. Studies using rheometry confirm the dependence of slip length on the surface texture. Drop impact tests and water immersion tests confirm the robustness of the air layer, entrapped on the SHSs, against large pressure perturbations. A visualization of flow over the SHSs in turbulent regime showed a viscous drag reduction of up to 30% for a flow with a Reynolds number of Reτ ~ 1000 defined with viscous length scale<br/>

Effect of surface texture in achieving large slip lengths on drag reducing robust super-hydrophobic surfaces (SHSs)

254th National Meeting (2017)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.