Effect of compressibility on the velocity gradient tensor at free shear flow boundaries

Mathew, Joseph and Ghosh, S (2011) Effect of compressibility on the velocity gradient tensor at free shear flow boundaries. In: 7th International Symposium on Turbulence and Shear Flow Phenomena, July 28 - 31, 2011, Ottawa, Canada.

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Abstract

Analyses of the invariants of the velocity gradient ten- sor were performed on flow fields obtained by DNS of compressible plane mixing layers at convective Mach num- bers Mc=0:15 and 1.1. Joint pdfs of the 2nd and 3rd invariants were examined at turbulent/nonturbulent (T/NT) boundaries—defined as surfaces where the local vorticity first exceeds a threshold fraction of the maximum of the mean vorticity. By increasing the threshold from very small lev-els, the boundary points were moved closer into the turbulent region, and the effects on the pdfs of the invariants were ob-served. Generally, T/NT boundaries are in sheet-like regions at both Mach numbers. At the higher Mach number a distinct lobe appears in the joint pdf isolines which has not been ob-served/reported before. A connection to the delayed entrain-ment and reduced growth rate of the higher Mach number flow is proposed.

Item Type:	Conference Paper
Publisher:	TSFP
Additional Information:	Copyright of this article belongs to TSFP.
Department/Centre:	Division of Mechanical Sciences > Aerospace Engineering(Formerly Aeronautical Engineering)
Date Deposited:	02 May 2013 09:38
Last Modified:	02 May 2013 09:38
URI:	http://eprints.iisc.ac.in/id/eprint/46285

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