Evanescent-Wave Visualizations of the Viscous Sublayer in Turbulent Channel Flow
Abstract
The study of wall turbulence dates back more than a century. Recently, however, a number of studies suggest that the flow in the inner region (i.e., the viscous sublayer and buffer layer) is not universaland actually depends upon the specific type of wall turbulence. Many of these new insights on wall turbulence are recent because we have only recently developed the experimental techniques, such as volumetric particle-image velocimetry, to fully resolve wall turbulent flows. The objective of the study described here was to determine whether an even more recent technique, evanescent-wave particle tracking velocimetry (PTV), could be used to visualize a plane (with dimensions exceeding 100 wall units) of the viscous sublayer parallel to the wall in fully-developed turbulent channel flow. Although the start of this study was delayed by visa issues, we have, after six months of work, demonstrated that the initial version of our evanescent wave illumination and imaging system can obtain high-quality images of the tracer particles with a temporal and spatial resolution suitable for wall turbulence that are suitable for PTV analysis, using only 30% of the available laser power.
Document Details
- Document Type
- Technical Report
- Publication Date
- Sep 02, 2015
- Accession Number
- AD1001426
Entities
People
- Minami Yoda
Organizations
- Georgia Tech Research Corporation