# Internal wave energy radiated from a turbulent mixed layer

## Abstract

We examine mixed-layer deepening and the generation of internal waves in stratified fluid resulting from turbulence that develops in response to an applied surface stress. In laboratory experiments the stress is applied over the breadth of a finite-length tank by a moving roughened conveyor belt. The turbulence in the shear layer is characterized using particle image velocimetry to measure the kinetic energy density. The internal waves are measured using synthetic schlieren to determine their amplitudes, frequencies, and energy density. We also perform fully nonlinear numerical simulations restricted to two dimensions but in a horizontally periodic domain. These clearly demonstrate that internal waves are generated by transient eddies at the integral length scale of turbulence and which translate with the background shear along the base of the mixed layer. In both experiments and simulations we find that the energy density of the generated waves is 1%–3% of the turbulent kinetic energy density of the turbulent layer.

- Authors:

- Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3X7 (Canada)
- Departments of Physics and Earth and Atmospheric Sciences, University of Alberta, Edmonton, Alberta T6G 2R3 (Canada)

- Publication Date:

- OSTI Identifier:
- 22311057

- Resource Type:
- Journal Article

- Journal Name:
- Physics of Fluids (1994)

- Additional Journal Information:
- Journal Volume: 26; Journal Issue: 9; Other Information: (c) 2014 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 1070-6631

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; COMPUTERIZED SIMULATION; CONVEYORS; DENSITY; ENERGY DENSITY; FLUIDS; INTERNAL WAVES; KINETIC ENERGY; LAYERS; LENGTH; PERIODICITY; SHEAR; STRESSES; TURBULENCE

### Citation Formats

```
Munroe, James R., E-mail: jmunroe@mun.ca, and Sutherland, Bruce R., E-mail: bsuther@ualberta.ca.
```*Internal wave energy radiated from a turbulent mixed layer*. United States: N. p., 2014.
Web. doi:10.1063/1.4895645.

```
Munroe, James R., E-mail: jmunroe@mun.ca, & Sutherland, Bruce R., E-mail: bsuther@ualberta.ca.
```*Internal wave energy radiated from a turbulent mixed layer*. United States. doi:10.1063/1.4895645.

```
Munroe, James R., E-mail: jmunroe@mun.ca, and Sutherland, Bruce R., E-mail: bsuther@ualberta.ca. Mon .
"Internal wave energy radiated from a turbulent mixed layer". United States. doi:10.1063/1.4895645.
```

```
@article{osti_22311057,
```

title = {Internal wave energy radiated from a turbulent mixed layer},

author = {Munroe, James R., E-mail: jmunroe@mun.ca and Sutherland, Bruce R., E-mail: bsuther@ualberta.ca},

abstractNote = {We examine mixed-layer deepening and the generation of internal waves in stratified fluid resulting from turbulence that develops in response to an applied surface stress. In laboratory experiments the stress is applied over the breadth of a finite-length tank by a moving roughened conveyor belt. The turbulence in the shear layer is characterized using particle image velocimetry to measure the kinetic energy density. The internal waves are measured using synthetic schlieren to determine their amplitudes, frequencies, and energy density. We also perform fully nonlinear numerical simulations restricted to two dimensions but in a horizontally periodic domain. These clearly demonstrate that internal waves are generated by transient eddies at the integral length scale of turbulence and which translate with the background shear along the base of the mixed layer. In both experiments and simulations we find that the energy density of the generated waves is 1%–3% of the turbulent kinetic energy density of the turbulent layer.},

doi = {10.1063/1.4895645},

journal = {Physics of Fluids (1994)},

issn = {1070-6631},

number = 9,

volume = 26,

place = {United States},

year = {2014},

month = {9}

}