Author:
MONTGOMERY MICHAEL T.,VLADIMIROV VLADIMIR A.,DENISSENKO PETR. V.
Abstract
Mesovortices in the eyewall region of a hurricane are intriguing elements of the
hurricane engine. In-situ measurements of them are sparse, however, and our understanding of their overall role in the physics of a hurricane is incomplete. To further
understand their dynamics an experimental apparatus using a homogeneous fluid
(water) has been constructed to emulate the lower tropospheric flow of the hurricane
eye/eyewall region.For experimental configurations possessing a central aspect ratio less than unity, a
primary and secondary circulation similar to the in flow layer of an intense hurricane,
and a similar radius-to-width ratio of the curvilinear shear layer bordering the eye and
eyewall region, the flow supports two primary quasi-steady vortices and secondary
intermittent vortices. The vortices form through Kelvin–Helmholtz instability of the
curvilinear shear layer bordering the slowly upwelling fluid in the centre and the converging fluid from the periphery. The primary vortices are maintained by convergence
of circulation from the periphery and merger of secondary vortices spawned along
the shear layer.The horizontal flow field is measured using a particle image velocimeter. Despite
the relatively strong secondary circulation through the parent vortex the horizontal
flow is found to be approximately uniform in the direction parallel to the rotation
axis. The peak tangential velocity is found to occur in the mesovortices and is roughly
50% greater than the parent vortex that supports them. The measurements provide
insight into recent observations of excessive wind damage in landfalling storms and
support the hypothesis that intense storms contain coherent vortex structures in the
eyewall region with higher horizontal wind speeds locally than the parent hurricane.
Publisher
Cambridge University Press (CUP)
Subject
Mechanical Engineering,Mechanics of Materials,Condensed Matter Physics
Cited by
81 articles.
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