Permeable coatings for turbulent drag reduction
Abstract
This project focuses on the use of coatings with anisotropic permeability to reduce turbulent skin friction. The idea is to exploit optimally the drag beneficial mechanisms present in existing technologies, such as riblets, while minimizing the effect of drag adverse mechanisms, to obtain a more robust performance. Preliminary work suggests that the present technology could outperform riblets by at least a factor of two, with drag reductions of order 20–25% at laboratory Reynolds numbers. This figures have however been obtained assuming a set of macroscopic parameters to characterize the microscale flow within the permeable substrate, without considering how the microscopic arrangement of obstacles-fibers would actually yield those macroscopic parameters. In the present project, we propose to focus on the microscopic flow for specific microscale configurations. We aim to assess quantitatively how details such as the ratio of radius to spacing of fibers, the fiber cross sectional shape, or the pattern of arrangement of the fibers affect the macroscale parameters. The first objective is to validate the continuum, macroscale models used so far, correcting them if necessary. The second objective is to provide guidelines for optimal configurations, as well as estimates for the realistic limits of the macroscopic parameters. The understanding gained will be tested in a handful of direct numerical simulations.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 14, 2022
- Source ID
- FA95501917050
Entities
People
- Ricardo Garcia-Mayoral
Organizations
- Air Force Office of Scientific Research
- United States Air Force
- University of Cambridge