Department of Mechanical Engineering

Towards Taming Turbulence Near Surfaces

Flow Control

Towards Taming Turbulence Near Surfaces

Turbulence may be thought of as the chaotic state that most fluid flows attain in practice. To an engineer, turbulent flows are frequently undesirable as they, for example, increase the air resistance to the movement of vehicles, decreasing the fuel economy and increasing the cost of operation. In many instances, turbulence is generated in the fluid layer immediately adjacent to the surface of the moving object, known as the boundary layer.


In a multi-university, cross-disciplinary, international effort, Ahmed Naguib is developing methods for adaptive control of boundary layers. Though the focus thus far has been on impeding the inherent tendency of near-wall flows to

become turbulent, the control methodology could also provide the foundation of the more challenging task of controlling near-wall turbulence directly. Dr. Naguib  embeds sensor arrays in surfaces to detect extremely small disturbances within the boundary layer and activates devices, known as plasma actuators, to produce “counter disturbances” to oppose the naturally growing disturbances and prevent, or delay, the transition to a turbulent state. Questions regarding where, when, and how much actuation should be exercised, and how does a natural disturbance differ from that caused by actuation, are just a handful of many questions being answered in Dr. Naguib’s research. The goal is to arrive at complete autonomous systems that can be embedded in the surface of vehicles to mitigate, or weaken near-wall turbulence.