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| Titel |
Boundary Layer Flow Over a Moving Wavy Surface |
| VerfasserIn |
Gali Hendin, Yaron Toledo |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250132713
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| Publikation (Nr.) |
 EGU/EGU2016-13245.pdf |
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| Zusammenfassung |
| Boundary Layer Flow Over a Moving Wavy Surface
Gali Hendin(1), Yaron Toledo(1)
January 13, 2016
(1)School of Mechanical Engineering, Tel-Aviv University, Israel
Understanding the boundary layer flow over surface gravity waves is of
great importance as various atmosphere-ocean processes are essentially coupled through these waves. Nevertheless, there are still significant gaps in our
understanding of this complex flow behaviour. The present work investigates the
fundamentals of the boundary layer air flow over progressive, small-amplitude
waves. It aims to extend the well-known Blasius solution for a boundary layer
over a flat plate to one over a moving wavy surface. The current analysis pro-
claims the importance of the small curvature and the time-dependency as second
order effects, with a meaningful impact on the similarity pattern in the first order. The air flow over the ocean surface is modelled using an outer, inviscid
half-infinite flow, overlaying the viscous boundary layer above the wavy surface.
The assumption of a uniform flow in the outer layer, used in former studies,
is now replaced with a precise analytical solution of the potential flow over a
moving wavy surface with a known celerity, wavelength and amplitude. This
results in a conceptual change from former models as it shows that the pressure variations within the boundary layer cannot be neglected. In the boundary
layer, time-dependent Navier-Stokes equations are formulated in a curvilinear,
orthogonal coordinate system. The formulation is done in an elaborate way
that presents additional, formerly neglected first-order effects, resulting from
the time-varying coordinate system. The suggested time-dependent curvilinear
orthogonal coordinate system introduces a platform that can also support the
formulation of turbulent problems for any surface shape. In order to produce
a self-similar Blasius-type solution, a small wave-steepness is assumed and a
perturbation method is applied. Consequently, a novel self-similar solution is
obtained from the first order set of equations. A second order solution is also
obtained, stressing the role of small curvature on the boundary layer flow. The
proposed model and solution for the boundary layer problem overlaying a moving wavy surface can also be used as a base flow for stability problems that can
develop in a boundary layer, including phases of transitional states. |
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