Investigations of eddy coherence in jet flows
- Yule, A. J.
- JAN 1, 1980.
- Physical Description:
- 1 electronic document
- Restrictions on Access:
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- In turbulent shear flow the term coherent structures refers to eddies which are both spatially coherent, i.e., large eddies, aand also temporally coherent, i.e., they retain their identities for times which are long compared with their time scales in fixed point measurements. In transitional flows, the existence of such structures is evident from flow visualizations. In many other flows, such structures are not so evident. The reasons for the existence of these two classes of flows are discussed and attention is focused upon the more difficult flows, where coherent structures are not so evident. Techniques by which the existence (or nonexistence) of such structures in these flows can be established from point measurements, are also discussed. A major problem is shown to be the need to discriminate between real losses in eddy coherence and apparent losses in coherence introduced by phase scrambling effects which 'smear' multipoint correlations. The analysis of multiprobe time dependent data in cold and reacting round turbulent jets is described and it is shown how evidence of strong eddy coherence can be extracted from data.
- Other Subject(s):
- NASA Technical Reports Server (NTRS) Collection.
- Document ID: 19800023252.
Accession ID: 80N31759.
Intern. Conf. on the Role of Coherent Structures in Modelling Turbulence and Mixing; 25-27 Jun. 1980; Madrid.
- No Copyright.
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