每年出版 12 期
ISSN 打印: 1091-028X
ISSN 在线: 1934-0508
Indexed in
Downslope Movement of Compositionally Driven Gravity Flows over Porous Surfaces
摘要
In many situations that involve gravity current flows over surfaces these same surfaces may not be impervious to the passage of fluid and so should be treated as porous media. The volumetric flux of fluid through the porous bottom may, in turn, have a profound effect on the structure as well as the spatiotemporal evolution of the current, influencing such things as rate and extent of spreading and the formation of internal bores. It is our intention here to present a model for the passage of heavy fluids down porous slopes under lighter ambient fluids surmounted by a free surface. The equations that describe these two-layer flows are derived from the NavierStokes equations in the small aspect ratio flow regime. We consider constant density inviscid fluids, neglecting surface tension and entrainment between the layers. The bottom boundary condition is designed to allow for a volumetric flux of fluid from the gravity current across the sloping bottom boundary. We study fixed volume releases of heavy fluid as we believe that such flows represent an appropriate paradigm for many atmospheric, oceanic, and human-made gravity currents. Various parameter regimes for these flows are explored numerically and the accuracy of the numerical procedure is examined. Comparison of our model-based numerical computations of the distance to extinction of this fully time-dependent bottom flow with the reported experimental results indicates both that our model captures the salient features of such flows and that our numerical scheme is accurate.
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Marino B. M., Thomas L. P., Spreading of a Gravity Current over a Permeable Surface, Journal of Hydraulic Engineering, 128, 5, 2002. Crossref