| dc.contributor.author | MacAulay, Phillip N. | en_US |
| dc.date.accessioned | 2014-10-21T12:37:16Z | |
| dc.date.available | 2004 | |
| dc.date.issued | 2004 | en_US |
| dc.identifier.other | AAINQ89809 | en_US |
| dc.identifier.uri | http://hdl.handle.net/10222/54616 | |
| dc.description | Interactions among incident waves, wave groups, infra-gravity waves and current flows in the nearshore bottom boundary layer (NBBL) are investigated using: (1) a novel 2D remote acoustic field technique for sampling vertical cross-sections of suspended sediments (the sector-scan); (2) hydrogen-bubble flow-visualization of NBBL flow under wave groups in a wave flume; and (3) a 1D, kepsilon numerical model to predict NBBL flows and suspension. | en_US |
| dc.description | The flume and field observations indicate that features of suspension over wave group timescales at large scales are important, but their time and space evolution are not immediately explicable in terms of simple models that include instantaneous forcing but ignore wave history. As turbulence is the cause of suspension, we look to turbulence for explanation. | en_US |
| dc.description | A near bed, low-frequency (LF) wall-jet-like flow is documented following wave groups in the wave flume. Flat bed field observations at Sandyduck97 indicate that behavior of NBBL suspension above the incident wave boundary layer is categorized by three regimes based primarily on the strength of the long-shore current. For weak to moderate long-shore currents a repeating pattern of infra-group suspension evolution is described. Suspension is generally restricted to the near bed under wave groups, but following wave groups suspension expands vertically in large plumes exceeding 30--40 cm in vertical and horizontal scale. For strong currents pluming can be nearly continuous. | en_US |
| dc.description | NBBL behavior is investigated with the kepsilon model through prediction of a series of increasingly complex NBBL flows leading up to typical NBBL conditions. Model predictions for typical NBBL conditions illustrate that a repeating, vertically veering three-dimensional LF flow is present during many wave groups. A two-part hypothesis describes suspension evolution during a wave group under typical NBBL conditions. Pluming following wave groups is attributed to cross-flow instability of the LF flow. | en_US |
| dc.description | The kepsilon predictions of the flume observations reproduce wall-jet flows observed in the flume, revealing their underlying Eulerian physics. Prediction of LF flows for Sandyduck97 data sets supports the hypothesis of suspension evolution through a wave group. Disparities between predicted and observed suspension events indicate that the kepsilon model is limited in its ability to predict turbulence, suspension, and flow development under three-dimensional flow conditions. | en_US |
| dc.description | Thesis (Ph.D.)--Dalhousie University (Canada), 2004. | en_US |
| dc.language | eng | en_US |
| dc.publisher | Dalhousie University | en_US |
| dc.publisher | | en_US |
| dc.subject | Biology, Oceanography. | en_US |
| dc.title | Nearshore bottom boundary layer responses to complex forcing. | en_US |
| dc.type | text | en_US |
| dc.contributor.degree | Ph.D. | en_US |
