Oil Spreading in instantaneous and continuous spills on rotating earth

Abstract

The effect of the Coriolis force on the oil slick spreading in gravity-viscous regime is examined.A new shallow-water model for transport and spreading of slick of arbitrary shape is described.The oil-water friction is parameterized in frame of boundary layer theory including the Ekmanlayer friction. The model also takes into account the Coriolis force in the momentum equations.The numerical Lagrangian method based on smoothed particle dynamics is described. Newsimilarity solutions of the model equations are obtained for unidirectional and axisymmetricspreading in gravity-viscous, gravity-turbulent and gravity-viscous-rotational regimes forinstantaneous as well as continuous releases. The numerical simulation extends these resultsfor the case of continuous release in the field of currents. It was shown that Coriolis term in themomentum equation can be omitted if slick thickness is much less of the laminar Ekman layerthickness. However, the Ekman friction should be retained at any thickness of slick for largetimes. The Ekman friction results in the essential slowdown of the spreading as well as in thedeflection of the oil spreading velocity at 45o from the direction of velocity in the non-rotationcase. Numerical simulations of large-scale spills showed that after two days the area of slick withCoriolis effect was in approximately in two time less of slick without rotation. Therefore, Earthframe of boundary layer theory including the Ekmanlayer friction. The model also takes into account the Coriolis force in the momentum equations.The numerical Lagrangian method based on smoothed particle dynamics is described. Newsimilarity solutions of the model equations are obtained for unidirectional and axisymmetricspreading in gravity-viscous, gravity-turbulent and gravity-viscous-rotational regimes forinstantaneous as well as continuous releases. The numerical simulation extends these resultsfor the case of continuous release in the f