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| Titel |
Effects of the Coriolis force on the oil spreading in instantaneous and continuous spill |
| VerfasserIn |
Igor Brovchenko, Vladimir Maderich, Kyung Tae Jung |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250071905
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| Zusammenfassung |
| The possible effects of the Coriolis force on the oil spill spreading have not yet investigated
or even discussed despite the spreading time scale for large spills can be of many hours and
days and releases can last days and months like in the “Ixtoc I” and “Deep Horizon” spills.
Therefore, it is important to quantify possible effects of the Coriolis force on the dynamics of
spreading of surface slick caused by continuous and instantaneous releases. The main goal of
this work is to explore does the Coriolis force affect the oil slick spreading in gravity viscous
regime. For this study a new shallow-water model for transport and spreading of slick of
arbitrary shape was developed. The governing equations for oil slick are derived
in shallow water approximation by means of the continuity and the momentum
equations integrated over the oil layer in which the inertial terms are neglected
and is assumed balance between gravity, frictional and the Coriolis forces. The
oil-water friction is parameterized in frame of boundary layer theory including the
Ekman layer friction. The numerical Lagrangian method based on smoothed particle
dynamics is described. New similarity solutions of the model equations are obtained for
unidirectional and axisymmetric spreading in gravity-viscous and gravity-viscous-rotational
regimes for instantaneous and continuous releases. The results are extended for the
case of continuous release in the field of currents by numerical simulation. It was
shown that Coriolis term in the momentum equation can be omitted if slick thickness
is much less of the laminar Ekman layer thickness. However, the Ekman friction
should be retained at any thickness of slick for large times. The Ekman friction
results in the essential slowdown of the spreading as well as in the deflection of
the oil spreading velocity at 45o from the direction of velocity in the non-rotation
case.
The new most important feature of the gravity-viscous-rotational regime is appearance of the
circumferential velocity due to the Coriolis force. The oil moved away from the center of
axisymmetric slick by spiral. The velocity components grow with distance from center of
slick in the case of instantaneous spill whereas for constant release rate both components of
velocity increase to the center of slick. In both cases circumferential velocity does not
disappear at the edge of the slick. However, near the edge of slick thickness of boundary layer
is less then the Ekman layer and vectors of spreading velocity should be directed normally to
the edge.
In the real cases the flux from underwater blowout is distributed over some area of surface. In
the case of point source the inertial terms in the momentum equations should be taken into
account. The full numerical solution for instantaneous release coincides with analytical
solution whereas asymptotic solution agrees well with full solution except inner area of the
slick. It was sown that Coriolis force effect can significantly decrease oil slick area after few
days after release. Therefore, Earth rotation can be important for the oil transport and
weathering. |
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