The University of Southampton
Engineering and the Environment

Research project: Universality of fine-scale turbulence

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This project links with others at Imperial College London and the University of Cambridge to develop and employ a series of advanced laser diagnostic techniques to measure the time-resolved, three-dimensional features of the fine-scales in a series of 'canonical' turbulent shear test flows in order to test the hypothesis of universality. 

Project Overview

Most flows of practical interest are turbulent, therefore a greater understanding of these flows is important for both engineering and fundamental reasons.  Unfortunately turbulence remains "the most important unsolved problem of classical physics". 

A turbulent flow consists of a wide range of three-dimensional motions, from large and slow to small and fast.  The smallest (and most rapid) motions dissipate the kinetic energy of the flow and determine drag on bodies, dispersion of pollutants and chemical mixing.  Unfortunately the very smallness of these motions has, until recently, made them inaccessible to both experiments and computations in flows of practical importance.  Predictions of turbulent flows have thus been based on uncertain theories and models of these 'fine scales', which are assumed to be the same for all flows i.e. universal.  No-one knows if this is true or not. 

Answering this question requires measurements of a range of flows using techniques capable of resolving their full structure in space as it evolves in time.  New techniques developed by the team have, for the first time, made the full measurements of these motions possible.  Similar advances in computational methods has provided the opportunity for meaningful comparisons with such measurements.

Measurements are taken at Reynolds numbers accessible to Direct Numerical Simulations especially carried out with this purpose for cross-comparison and validation.  These experimental techniques are based on cinematographic scanning and tomographic Particle Image Velocity (PIV) techniques.  Regardless of whether the universality hypothesis holds or not, the necessary information to formulate physics based fine-scale models that can account for multi-scale interactions will be obtained.  This data, as well as the 3D PIV software, will ultimately be made available online for researchers in the UK and around the world.

Related research groups

Aerodynamics and Flight Mechanics

Staff

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