Print Email Facebook Twitter Long-range lPIV to resolve the small scales in a jet at high Reynolds number Title Long-range lPIV to resolve the small scales in a jet at high Reynolds number Author Fiscaletti, D. Westerweel, J. Elsinga, G.E. Faculty Mechanical, Maritime and Materials Engineering Department Process and Energy Date 2014-08-28 Abstract The investigation of flows at high Reynolds number is of great interest for the theory of turbulence, in that the large and the small scales of turbulence show a clear separation. But, as the Reynolds number of the flow increases, the size of the Kolmogorov length scale ( ? ) drops almost proportionally. Aiming at achieving the adequate spatial resolution in the central region of a self-similar round jet at high Reynolds numbers ( Re??350 ), a long-range ?PIV system was applied. A vector spacing of 1.5? was achieved, where the Kolmogorov length scale was estimated to be 55?m . The resulting velocity fields were used to characterize the small-scale flow structures in this jet. The autocorrelation maps of vorticity and ?ci (the imaginary part of the eigenvalue of the reduced velocity gradient tensor) reveal that the structures of intense vorticity have a characteristic diameter of approximately 10? . From the autocorrelation map of the reduced (2D) rate of dissipation, it is inferred that the regions of intense dissipation tend to organize in the form of sheets with a characteristic thickness of approximately 10? . The regions of intense dissipation have the tendency to appear in the vicinity of intense vortices. Furthermore, the joint pdf of the two invariants of the reduced velocity gradient tensor exhibits the characteristic teapot-shape. These results, based on a statistical analysis of the data, are in agreement with previous numerical and experimental studies at lower Reynolds number, which validates the suitability of long-range ?PIV for characterizing turbulent flow structures at high Reynolds number. Subject long-range ?PIVsmall scaleshigh Reynolds number To reference this document use: http://resolver.tudelft.nl/uuid:c23e8332-c2d5-41ee-8546-b6a49de2df38 DOI https://doi.org/10.1007/s00348-014-1812-7 Publisher Springer ISSN 0723-4864 Source http://link.springer.com/article/10.1007%2Fs00348-014-1812-7 Source Experiments in Fluids, 55 (9), 2014 Part of collection Institutional Repository Document type journal article Rights (c) 2014 The Author(s) Files PDF 307994.pdf 1.67 MB Close viewer /islandora/object/uuid:c23e8332-c2d5-41ee-8546-b6a49de2df38/datastream/OBJ/view