, Volume 12, Issue 6, pp 495513
Numerical simulation of particledriven gravity currents
 Sangdo AnAffiliated withDepartment of Civil and Environmental Engineering, Colorado State University Email author
 , Pierre Y. JulienAffiliated withDepartment of Civil and Environmental Engineering, Colorado State University
 , Subhas K. VenayagamoorthyAffiliated withDepartment of Civil and Environmental Engineering, Colorado State University
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Particledriven gravity currents frequently occur in nature, for instance as turbidity currents in reservoirs. They are produced by the buoyant forces between fluids of different density and can introduce sediments and pollutants into water bodies. In this study, the propagation dynamics of gravity currents is investigated using the FLOW3D computational fluid dynamics code. The performance of the numerical model using two different turbulence closure schemes namely the renormalization group (RNG) \({k\epsilon}\) scheme in a Reynoldaveraged NavierStokes framework (RANS) and the largeeddy simulation (LES) technique using the Smagorinsky scheme, were compared with laboratory experiments. The numerical simulations focus on two different types of density flows from laboratory experiments namely: Intrusive Gravity Currents (IGC) and ParticleDriven Gravity Currents (PDGC). The simulated evolution profiles and propagation speeds are compared with laboratory experiments and analytical solutions. The numerical model shows good quantitative agreement for predicting the temporal and spatial evolution of intrusive gravity currents. In particular, the simulated propagation speeds are in excellent agreement with experimental results. The simulation results do not show any considerable discrepancies between RNG \({k\epsilon}\) and LES closure schemes. The FLOW3D model coupled with a particle dynamics algorithm successfully captured the decreasing propagation speeds of PDGC due to settling of sediment particles. The simulation results show that the ratio of transported to initial concentration C _{ o }/C _{ i } by the gravity current varies as a function of the particle diameter d _{ s }. We classify the transport pattern by PDGC into three regimes: (1) a suspended regime (d _{ s } is less than about 16 μm) where the effect of particle deposition rate on the propagation dynamics of gravity currents is negligible i.e. such flows behave like homogeneous fluids (IGC); (2) a mixed regime (16 μm < d _{ s }<40 μm) where deposition rates significantly change the flow dynamics; and (3) a deposition regime (d _{ s } > 40 μm) where the PDGC rapidly loses its forward momentum due to fast deposition. The present work highlights the potential of the RANS simulation technique using the RNG \({k\epsilon}\) turbulence closure scheme for field scale investigation of particledriven gravity currents.
Keywords
Gravity currents Density currents Buoyant forces Computational fluid dynamics (CFD) Lockexchange flows Particle settling Environmental fluid mechanics Title
 Numerical simulation of particledriven gravity currents
 Journal

Environmental Fluid Mechanics
Volume 12, Issue 6 , pp 495513
 Cover Date
 201212
 DOI
 10.1007/s1065201292516
 Print ISSN
 15677419
 Online ISSN
 15731510
 Publisher
 Springer Netherlands
 Additional Links
 Topics
 Keywords

 Gravity currents
 Density currents
 Buoyant forces
 Computational fluid dynamics (CFD)
 Lockexchange flows
 Particle settling
 Environmental fluid mechanics
 Authors

 Sangdo An ^{(1)}
 Pierre Y. Julien ^{(1)}
 Subhas K. Venayagamoorthy ^{(1)}
 Author Affiliations

 1. Department of Civil and Environmental Engineering, Colorado State University, Fort Collins, CO, 805231372, USA