Investigation of Drag in Viscoelastic Turbulent Channel Flow With Slip

The problem of reducing skin-friction drag has endured and is one of the long-stated motivations for research into energy savings. Many investigations have looked into various approaches to achieve skin-friction reduction. One of the most successful approaches is to add a small amount of long-chain, linear polymers to a fluid. The polymer additives can lead to significant drag reduction of upwards of 80%. Another successful approach involves superhydrophobic surfaces, allowing for slip at the wall. Superhydrophobic surfaces have been shown to achieve a skin-friction drag reduction of 20-30% in the turbulent regime. The polymer additive and superhydrophobic surface approaches give different and important insights to drag reduction. Therefore, identifying a link between these two distinct approaches would be an important advancement in our understanding of turbulence flow control. In the present study, direct numerical simulations of a turbulent channel flow were performed with the inclusion of both surface slip and polymer additives. When using the combined techniques, preliminary results show an increase in drag when compared to each respective technique. Detailed mechanisms responsible for increased drag will be explored and discussed further.