Establishing Universal Scaling Laws for Pressure Fluctuations in High Reynolds Number Rough Wall Turbulent
Abstract
The overarching objective of this work is to establish the scaling of wall pressure fluctuations in high Reynolds number rough wall boundary layers. Recent work, involving large scale experiments on fully rough surfaces formed from small hemispherical elements, has begun to shed light on this previously neglected regime. These measurements suggest that wall-pressure spectrum at these conditions has three scaling regions, controlled at mid-frequency by the Strouhal number of the roughness elements, and anchored at high frequency by a new viscous scaling that depends on the substrate friction velocity ???? – the friction velocity adjusted to exclude the pressure drag on the roughness elements. The work we are proposing here addresses fundamental issues raised by this new insight. We outline an experimental program that will directly establish the persistence of these scalings, and thus of the physical processes they imply, as the geometry of the roughness is varied and as the roughness density is increased to the point where the substrate ceases to be dynamically significant. Also proposed are experiments on a two-scale surface, to test the physical picture behind the triple scaling hypothesis, and the development of an interpolation function for rough-wall boundary layer pressure spectra. The work proposed here has already been partially funded, at the rate of 50%, by the National Science Foundation. The purpose of this proposal to ONR is to request the remaining 50% of the support. Total costs associated with this portion of the work are $228,300.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Aug 12, 2016
- Source ID
- N000141512247
Entities
People
- William J. Devenport
Organizations
- Office of Naval Research
- United States Navy
- Virginia Tech