Experimental study of the initial growth of a localized turbulent patch in a stably stratified fluid

Lilly Verso*, Maarten van Reeuwijk, Roi Gurka, Peter J. Diamessis, Zachary J. Taylor, Alex Liberzon

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

We present a laboratory experiment of the initial growth of a turbulent patch in a stably stratified fluid. The patch is created due to a localized source of turbulence, generated by a horizontally oriented and vertically oscillating grid much smaller than the tank size and far from solid boundaries. Synchronized and overlapping particle image velocimetry(PIV) and planar laser induced fluorescence (PLIF) measurements capture the evolution of the patch through its initial growth until it reached a maximum size. The simultaneous measurements of density and velocity fields allow for a direct quantification of the distribution of kinetic energy, buoyancy and degree of mixing within the patch. We can also relate the propagation speed of the turbulent/non-turbulent interface and its thickness to the properties of the turbulent fluid inside the evolving patch. The velocity measurements in this setup indicate significant transient effects inside the patch during its growth. A local analysis of the turbulent/non-turbulent interface provides direct measurements of the entrainment velocity we as compared to the local vertical velocity and turbulent intensity at the proximity of the interface. The detailed information about the growth of localized sources of turbulence in stratified environment might be of use in stealth design of autonomous underwater vehicles.

Original languageEnglish
Pages (from-to)127-136
Number of pages10
JournalInternational Journal of Heat and Fluid Flow
Volume66
DOIs
StatePublished - Aug 2017

Funding

FundersFunder number
Bi-National U.S. Israel Science Foundation2008051
Israel Science Foundation945/15
Azrieli Foundation

    Keywords

    • Local entrainment and stable stratification
    • Turbulent patch

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