Non-equilibrium cascade and large-scale dynamics in wall turbulence
Abstract
A lot of energy is required to move vehicles through air and water and also for such fluids to move inside pipes, ducts, containers and over various surfaces, throughout industry and engineering. This loss of energy is high because flows are typically turbulent and therefore dissipate energy in two ways: (i) through the presence of a multitudeof eddies over a wide range of sizes such that energy cascades from higher to lower size eddies till an eddy size is reached that is small enough for energy to be quickly dissipated by viscosity; and (ii) through direct "grinding"/friction of these eddies on solid surfaces. Our textbook understanding of this energy cascade is limited to turbulent flows far from surfaces and does not incorporate variations/fluctuations of energy dissipation even though such variations/fluctuations are nearly always present. Transformative advances over the past 10 years have (a) uncovered a new law for fluctuations and for the evolution of energy dissipation by turbulence away from surfaces and have (b) led to new analysis tools for the comprehensive and detailed study of energy exchanges and losses in turbulent flows. An unprecedented opportunity presents itself to apply these advances to the understanding of energy dissipation in turbulent flows interacting with surfaces. This project will do this for turbulent channel flow and aims to reveal how mechanisms (i) and (ii) interact and shape energy losses and their variations in time and space. The potential impact of this research is far reaching as it can lead to a major step change in our ways to predict turbulent flows and in our ways to design energy efficient engineering solutions in the presence of such flows across the board.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Jan 21, 2022
- Source ID
- FA86552117016XX0
Entities
People
- John-christos Vassilicos
Organizations
- Air Force Office of Scientific Research
- United States Air Force
- École Centrale de Lille