Published online by Cambridge University Press: 05 February 2013
The wide ranges of length and velocity scales that occur in turbulent flows make them both interesting and difficult to understand. The length scale range is widest in high Reynolds number turbulent wall flows where the dominant contribution of small scales to the stress and energy very close to the wall gives way to dominance of larger scales with increasing distance away from the wall. Intrinsic length scales are defined statistically by the two-point spatial correlation function, the power spectral density, conditional averages, proper orthogonal decomposition, wavelet analysis and the like. Before two- and three-dimensional turbulence data became available from PIV and DNS, it was necessary to attempt to infer the structure of the eddies that constitute the flow from these statistical quantities or from qualitative flow visualization. Currently, PIV and DNS enable quantitative, direct observation of structure and measurement of the scales associated with instantaneous flow patterns. The purpose of this chapter is to review the behavior of statistically-based scales in wall turbulence, to summarize our current understanding of the geometry and scales of various coherent structures and to discuss the relationship between instantaneous structures of various scales and statistical measures.
Introduction
Wall-bounded turbulent flows are pertinent in a great number of fields, including geophysics, biology, and most importantly engineering and energy technologies where skin friction, heat and mass transfer, flow-generated noise, boundary layer development and turbulence structure are often critical for system performance and environmental impact.
To save this book to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about saving to your Kindle.
Note you can select to save to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be saved to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
Find out more about the Kindle Personal Document Service.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Dropbox.
To save content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about saving content to Google Drive.