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http://dx.doi.org/10.3744/SNAK.2011.48.5.414

Formation of Coherent Vortices in Late Wake Downstream of an Object in Weakly Stratified Fluid  

Lee, Sung-Su (School or Civil Engineering, Chungbuk National University)
Kim, Hak-Sun (School or Civil Engineering, Chungbuk National University)
Publication Information
Journal of the Society of Naval Architects of Korea / v.48, no.5, 2011 , pp. 414-420 More about this Journal
Abstract
Decades of studies of geophysical flow have unveiled that the flow downstream of obstacles in stratified flow consists of attached wake and strong gravity waves, or separated, fluctuating wake and persistent late wakes. Among unique and interesting characteristics of the stratified flow past obstacles is the generation of coherent vortex in the late wake far downstream of the object. Unlike in homogeneous fluid, the flow field downstream self-develops coherent vortex even after diminishing of the near wake, no matter how small the stratification is. This paper present a computational approach to simulate the generation of the coherent vortex structure in the late wake of a moving sphere submerged in weakly stratified fluid. The results are in consistent with several experimental observations and the vortex stretching mechanism is employed to explain the process of coherence.
Keywords
Late wake; Stratification; FEM; Vortex shedding;
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