The effect of random roughness on turbulent boundary layers, from first principles
Abstract
Boundary layers of naval interest are hydrodynamically rough, and understanding the effect ofrough surfaces on turbulent flow structures is critical to predicting near-wall behavior and drag.However, state-of-the-art approaches to describing roughness and modeling its effects are highlyempirical; the bulk of our understanding is limited to boundary layers over smooth walls. Recentadvances in computational and systems-theoretic approaches make it possible to understand, andpredict the effects of roughness from first principles. We propose an integrated computational(Mahesh) and theoretical (Jovanovic) program to develop such understanding and predictivecapability. We propose to use (i) direct numerical simulations; (ii) modern stability analysis(both modal and non-modal); (iii) data-driven, reduced-order modeling; and (iv) theory ofdynamical systems with stochastic excitation sources to study turbulent flows over roughsurfaces. The proposed work will shed unprecedented insight into the microphysics of flow overrealistic rough surfaces, and develop a unique database for utilization by Reynolds-averaged andlarge-eddy simulation methodologies. It will develop a dynamical systems theory for the effectsof roughness, and develop physics-based reduced order models for rough wall boundary layers.The resulting impact will be profound - a new paradigm for how the effects of roughness areincluded in surface design, a foundation for how roughness might be accounted for in boundarylayer control strategies and finally, insight into the potential for tailoring surface roughness foroptimal performance.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- May 05, 2017
- Source ID
- N000141712308
Entities
People
- Krishnan Mahesh
Organizations
- Office of Naval Research
- Regents of the University of Minnesota
- United States Navy