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

详细信息    查看全文

• 作者：Christina L. Fandel ; Thomas C. Lippmann ; Diane L. Foster…
• 刊名：Geo-Marine Letters
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：37
• 期：1
• 页码：15-22
• 全文大小：
• 刊物类别：Earth and Environmental Science
• 刊物主题：Geology;
• 出版者：Springer Berlin Heidelberg
• ISSN：1432-1157
• 卷排序：37

文摘

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.