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| Titel |
Mixing of effluent in tidal coastal waters |
| VerfasserIn |
Chris Johnson, Andrew Hogg |
| 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 |
250077356
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| Zusammenfassung |
| Industrial effluent is commonly released into shallow coastal waters, where it is
subsequently transported by tidal currents and dispersed by mixing with the ambient.
The buoyancy of an effluent (either positive or negative) plays an important role in
its interaction with the surrounding ocean, and leads to the formation of gravity
currents, which flow along either the sea bed or surface, depending on the sign of the
buoyancy. We present a theoretical study of such gravity currents, including the
effects of mixing and/or a flowing ambient on the current dynamics, and find that
inclusion of mixing in depth-integrated gravity current models (in particular, the
dependence of such mixing, or entrainment, on the bulk Richardson number) results in
fundamental changes to the long-time behaviour of currents. For example, the long-time
behaviour of an instantaneous release of a fixed volume of dense effluent is similarity
solution of the second kind, in which the gravity current spreads as a power of
time that is dependent on the form of the entrainment model, approximately as
t0.44. A diverse range of flow regimes exist in which the effects of buoyancy-driven
spreading, mixing and the ambient flow are more or less important, but we find
that mixing generically plays an important role in gravity currents at late times. |
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