Experiments on layer formation in stratified shear flow

We discuss the experimental methodology and present the results of several experiments on the onset and growth of instabilities in stratified shear flow. Our results include the assessment of the effective diffusivity prior to the development of the Kelvin-Helmholtz (K-H) type instability and the me...

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Bibliographic Details
Published in:Scientia marina 2001-07, Vol.65 (S1), p.117-126
Main Authors: Cisneros-Aguirre, J, Pelegri, J, Sangra, P
Format: Article
Language:English
Subjects:
kelvin-helmholtz instability
layer structure
stratified shear flow
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Summary:We discuss the experimental methodology and present the results of several experiments on the onset and growth of instabilities in stratified shear flow. Our results include the assessment of the effective diffusivity prior to the development of the Kelvin-Helmholtz (K-H) type instability and the measurement of the velocity field. This allows us to determine that the onset of the instability takes place when the Richardson number is close to 0.25, this value slightly decreasing with increasing initial interface thickness. The formation of a fine layered structure at the interface is suggested by density profiles taken immediately after the generation of K-H billows, but the size of the full interface as well as the layers themselves decrease in the following few seconds. We hypothesize that the time scale of the K-H billows in our laboratory experiments is so short that there is no time for added mixing to further distribute and smoothen the initial layer structure.
ISSN:0214-8358
1886-8134
DOI:10.3989/scimar.2001.65s1117