Publication Date:
2002-07-10
Description:
Area-volume properties of fluid interfaces are investigated to quantify the scale-local and cumulative structure. An area-volume density g3(λ) and ratio Ω3(λ) are introduced to examine the interfacial behaviour as a function of scale λ or across a range of scales, respectively. These measures are demonstrated on mixed-fluid interfaces from whole-field ~10003 three-dimensional space-time concentration measurements in turbulent jets above the mixing transition, at Re ~ 20000 and Sc ~ 2000, recorded by laser-induced-fluorescence and digital-imaging techniques, with Taylor's hypothesis applied. The cumulative structure is scale dependent in Ω3(λ), with a dimension D3(λ) that increases with increasing scale. In contrast, the scale-local structure exhibits self-similarity in g3(λ) with an exponent αg ≈ 1.3 for these interfaces. The scale dependence in the cumulative structure arises from the large scales, while the self-similarity corresponds to the small-scale area-volume contributions. The small scales exhibit the largest area-volume density and provide the dominant contributions to the total area-volume ratio, which corresponds to ~ 10 times the area of a purely large-scale interface for the present flow conditions. The self-similarity in the scale-local structure at small scales provides the key ingredient to extrapolate the area-volume behaviour to higher Reynolds numbers.
Print ISSN:
0022-1120
Electronic ISSN:
1469-7645
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
