Statistical Scaling of Turbulent Surface Pressure in the Atmospheric Boundary Layer

<p>Turbulence in the atmosphere produces fluctuations in static pressure through a variety of mechanisms. These fluctuations are of interest both to atmospheric scientists, as a fluid dynamic property, and to acousticians, as a source of wind noise. At the ground surface, previous work has found the dominant source of pressure fluctuations to be an interaction of the turbulent vertical velocity with the shear rate in the mean wind. In this work, the existing theoretical framework was extended to investigate the effects of atmospheric stability, shear anisotropy, and different turbulence models. A rapid-distortion model was introduced and compared with the existing mirror-flow model. Solutions for the surface pressure spectra from each model were derived, and a method for estimating the model parameters from average elevation-dependent flow properties was developed. In order to validate and compare these spectral models, an experiment was conducted in Laramie, Wyoming to obtain measurements of low-frequency surface pressure simultaneous with the boundary-layer meteorology over a wide range of atmospheric conditions. The velocity data were then used to fit the turbulence model parameters, and predictions of the surface pressure spectra were made. These predictions were compared with the spectra of the surface pressure measurements over half-hour intervals, converted to wavenumber space by introducing a convection velocity. In stable conditions, a low-wavenumber amplification of the spectrum was observed, in accordance with predictions. In convection conditions, the rapid-distortion model performed best, and the shear anisotropy contained in this model was found to be relevant to fitting nearly-neutral cases. The modification of the spectral structure by the shear-anisotropic model suggests a possible unifying mechanism for discrepancies between engineering and atmospheric boundary-layer pressure statistics.</p>

Name thesis:degree_name

Ph.D. in Engineering Science

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Electrical Engineering

Year dc:date.available

2016

Author dc:creator

• Lyons, Gregory William

Contributors dc:contributor

• Nathan E. Murray
• Carrick L. Talmadge
• Richard Raspet

• Atmospheric acoustics
• Atmospheric turbulence
• Boundary layer meteorology
• Turbulence-generated noise
• Turbulent flow modeling
• Wall-bounded turbulent flows
• Engineering

Repository record dc:identifier

https://egrove.olemiss.edu/etd/1390

OAI identifier oai:identifier

oai:egrove.olemiss.edu:etd-2389