A proposal to study the effect of unsteady wall boundary conditions on turbulent boundary layers
Abstract
A novel air-film system that could produce a significant reduction in turbulent frictional drag by stably maintaining oscillating air-films in fully turbulent boundary layers (TBLs). We show that under certain mean air-film pressure and oscillation frequency, the dynamic interaction of air-films with TBL results in 10% - 30% wall- friction reduction. We show that this effect is related to the unsteady boundary condition generated by the air-film and appearance of Stokes-type oscillatory flow in the near-wall region. Such unsteady motion can potentially modify the TBL structure through a negative turbulent kinetic energy production term. Further understanding of the underlying mechanisms through experimental and computational efforts will provide valuable insights on the physics of wall-friction and design of strategies to control turbulence production in the near-wall region.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jun 13, 2019
- Source ID
- N000141912426
Entities
People
- Morteza Gharib
Organizations
- California Institute of Technology
- Office of Naval Research
- United States Navy