Open AccessEnhancement of turbulence through lateral spreading in a stratified‐shear flow: Development and assessment of a conceptual model
Author(s) -
MacDonald Daniel G.,
Chen Fei
Publication year - 2012
Publication title -
journal of geophysical research: oceans
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2011jc007484
Subject(s) - turbulence , turbulence kinetic energy , mechanics , shear flow , k epsilon turbulence model , geology , shear (geology) , scale (ratio) , stratified flow , plume , flow (mathematics) , field (mathematics) , stratified flows , meteorology , physics , statistical physics , mathematics , petrology , quantum mechanics , pure mathematics
A conceptual model for the impact of lateral spreading processes on local stratified‐shear turbulence is presented and evaluated using field data from the rapidly spreading near‐field region of the Merrimack River plume. The conceptual model addresses increases in turbulent kinetic energy associated with the stretching of a Kelvin‐Helmholz billow along its rotational axis. A non‐dimensional relationship is derived with two fit parameters, including a parameter representing the magnitude of mixing under the no spreading case, and a non‐dimensional time scale. For the model to be viable, this time scale, representing the period of time that a Kelvin‐Helmholz billow is subject to stretching should be of the same order as the evolution time scale for the billow. Observational data from field experiments are used to evaluate the two fit parameters, indicating a stretching time scale of the same order as evolution time scales reported in the literature. In addition, application of the model to the field data reduces observed variability. We conclude that spreading is an important mechanism capable of enhancing local stratified‐shear turbulence.