Towards Turbulent Drag Reduction On A Superhydrophobic Aluminum SLIPS Surface

Abstract

The ultimate objective of this study is to use experimental techniques in order to determine the potential drag reduction on a treated aluminum surface that has been coated with a Slippery Liquid-Infused Porous Surface (SLIPS) [1]. This surface consists of a micro- or nano-textured substrate that is infused with a lubricant, so that there is an oil-water interface at the boundary between the solid object and the surrounding water. Previous works have shown that conventional superhydrophobic surfaces, which rely on an air-water interface, can reduce drag on a solid body. However, these surfaces are not robust in turbulent flows since the air pockets that are designed to be trapped in the texture easily fail. We are interested in investigating if SLIPS, which is unique in that it relies on an oil-water interface, will reduce the drag on a treated aluminum surface while maintaining robustness in turbulent flow. The SLIPS surface is initially tested under laminar flow conditions using a rheometer. Results from tensiometer and rheometer measurements show that there may be drag reduction on the SLIPS surface compared to regular aluminum, and these measurements give hints as to what parameters are important. Furthermore, a water channel is designed and fabricated so that SLIPS experiments can be conducted involving micro-and macro-PIV in turbulent flow. Finally, future directions and experiments are described in the last chapter of the paper.