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KMID : 1024520140230071223
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Journal of the Environmental Sciences
2014 Volume.23 No. 7 p.1223 ~ p.1232
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Three-Dimensional Numerical Simulation of Intrusive Density Currents
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An Sang-do
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Abstract
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Density currents have been easily observed in environmental flows, for instance turbidity currents and pollutant plumes
in the oceans and rivers. In this study, we explored the propagation dynamics of density currents using the FLOW-3D
computational fluid dynamics code. The renormalization group (RNG) scheme, a turbulence numerical technique, is
employed in a Reynold-averaged Navier-Stokes framework (RANS). The numerical simulations focused on two different
types of intrusive density flows: (1) propagating into a two-layer ambient fluid; (2) propagating into a linearly stratified
fluid. In the study of intrusive density flows into a two-layer ambient fluid, intrusive speeds were compared with laboratory
experiments and analytical solutions. The numerical model shows good quantitative agreement for predicting propagation
speed of the density currents. We also numerically reproduced the effect of the ratio of current depth to the overall depth of
fluid. The numerical model provided excellent agreement with the analytical values. It was also clearly demonstrated that
RNG scheme within RANS framework is able to accurately simulate the dynamics of density currents. Simulations
intruding into a continuously stratified fluid with the various buoyancy frequencies are carried out. These simulations
demonstrate that three different propagation patterns can be developed according to the value of : (1) underflows
developed with ; (2) overflows developed when ; (3) intrusive interflow occurred with the condition of
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KEYWORD
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Density currents, Environmental flows, Computational Fluid Dynamics (CFD), FLOW-3D
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