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Observations of pockmark flow structure in Belfast Bay, Maine, Part 2: evidence for cavity flow

December 1, 2016

Pockmark flow circulation patterns were investigated through current measurements along the rim and center of two pockmarks in Belfast Bay, Maine. Observed time-varying current profiles have a complex vertical and directional structure that rotates significantly with depth and is strongly dependent on the phase of the tide. Observations of the vertical profiles of horizontal velocities in relation to relative geometric parameters of the pockmark are consistent with circulation patterns described qualitatively by cavity flow models (Ashcroft and Zhang 2005). The time-mean behavior of the shear layer is typically used to characterize cavity flow, and was estimated using vorticity thickness to quantify the growth rate of the shear layer horizontally across the pockmark. Estimated positive vorticity thickness spreading rates are consistent with cavity flow predictions, and occur at largely different rates between the two pockmarks. Previously modeled flow (Brothers et al. 2011) and laboratory measurements (Pau et al. 2014) over pockmarks of similar geometry to those examined herein are also qualitatively consistent with cavity flow circulation, suggesting that cavity flow may be a good first-order flow model for pockmarks in general.

Citation Information

Publication Year 2017
Title Observations of pockmark flow structure in Belfast Bay, Maine, Part 2: evidence for cavity flow
DOI 10.1007/s00367-016-0473-3
Authors Christina L. Fandel, Thomas C. Lippmann, Diane L. Foster, Laura L. Brothers
Publication Type Article
Publication Subtype Journal Article
Series Title Geo-Marine Letters
Index ID 70178646
Record Source USGS Publications Warehouse
USGS Organization Woods Hole Coastal and Marine Science Center