ISSN:
1432-1114
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract A digital technique is presented for experimentally measuring the local wavenumber-frequency spectrum S L(k, f) of a fluctuating velocity field using two probes. From S L(k, f), the local wavenumber spectrum S L(k), the averaged dispersion relation, and the broadening of the wavenumber spectrum for a given frequency can be determined. The technique is demonstrated by applying it to the velocity field of a plane wake which is undergoing transition from laminar to turbulent flow. A specially designed two sensor hotwire probe is used to obtain simultaneous records of streamwise velocity fluctuations at two locations having a fixed streamwise separation. New information is obtained concerning: the spatial characteristics of instability waves in the wake; the importance of local wavenumber matching in nonlinear coupling among waves; and broadening of the dispersion relation associated with the transition to turbulence. The usefulness of the S L(k, f) approach when Taylor's hypothesis is not valid is also discussed.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00196481
Permalink