Direct Numerical Simulations of the Impact of Smooth Humps on Laminar-Turbulent Transition

Abstract

Improving aviation’s ecological footprint is a current drive for the aerospace industry. Reducing the skin-friction drag can considerably mitigate the emission of pollutants and fuel consumption. One way to achieve this goal is to maintain the laminar flow on wings at a chord Reynolds number beyond what is usually transitional or turbulent. The potential benefits are important because transition separates the laminar region with low drag from the turbulent region where skin-friction dramatically increases. Real aerodynamic surfaces always present small irregularities resulting in steps, gaps and waviness. One of the major challenges for the implementation of laminar-flow surfaces is the potential for any irregularity to modify the stability of the boundary layer, hence transition location.