|Abstract or Summary
- This thesis presents the details of a large-scale laboratory experiment to study the
turbulence generated by waves breaking on a fixed barred beach. The data set includes
comprehensive measurements of free surface displacement and fluid velocity for one
random and one regular wave case.
Observations of the time-averaged turbulent kinetic energy per unit mass, k̄, show that
the turbulence generated by wave breaking was greatest at the bar crest and did not
fully dissipate prior to reaching the bed. This indicates that, even in a time-averaged
sense, wave breaking turbulence may be important for near-bed processes on a barred
beach. Onshore of the bar, turbulence was generally confined to the upper part of the
water colunm and dissipated once the waves reformed (approximately 1.5 wavelengths
onshore of the bar crest). The turbulent structure was the same in the random and
regular wave cases; however, the magnitude of k̄ was much less in the random wave
case, despite similar offshore wave conditions.
Three methods were used to separate the wave-induced and turbulent components of
velocity: ensemble averaging, high-pass filtering, and a differencing method proposed
by Trowbridge (1998). The magnitude of k̄ varied by as much as a factor of 5 among
these methods, but qualitatively, the cross-shore and vertical structure was
independent of the method used. The differencing method agreed closely with
ensemble averaging in terms of the magnitude and structure of time-averaged
quantities and in the signature of the time-dependent turbulent kinetic energy. Given
this agreement and the general acceptance of ensemble averaging as an appropriate
method to separate wave-induced and turbulent components of velocity for regular
waves (Svendsen 1987), the differencing method appears to be the most suitable for
application to random waves, such as those observed in the field.
- File scanned at 300 ppi (Monochrome, 256 Grayscale, 24-bit Color) using Capture Perfect 3.0.82 on a Canon DR-9080C in PDF format. CVista PdfCompressor 4.0 was used for pdf compression and textual OCR.
- description.provenance : Approved for entry into archive by Patricia Black(email@example.com) on 2011-03-03T22:29:56Z (GMT) No. of bitstreams: 1ScottChristopherP2005.pdf: 4220493 bytes, checksum: bb2c7dfe59425fa7d03b76fe66733a97 (MD5)
- description.provenance : Made available in DSpace on 2011-03-04T17:56:39Z (GMT). No. of bitstreams: 1ScottChristopherP2005.pdf: 4220493 bytes, checksum: bb2c7dfe59425fa7d03b76fe66733a97 (MD5) Previous issue date: 2005-02-25
- description.provenance : Submitted by Erin Clark (firstname.lastname@example.org) on 2011-03-03T18:48:11ZNo. of bitstreams: 1ScottChristopherP2005.pdf: 4220493 bytes, checksum: bb2c7dfe59425fa7d03b76fe66733a97 (MD5)
- description.provenance : Approved for entry into archive by Patricia Black(email@example.com) on 2011-03-04T17:56:39Z (GMT) No. of bitstreams: 1ScottChristopherP2005.pdf: 4220493 bytes, checksum: bb2c7dfe59425fa7d03b76fe66733a97 (MD5)