Large Eddy Simulation of suspended sediment transport

2014 ◽  
pp. 867-874
Author(s):  
M Dallali ◽  
V Armenio
Keyword(s):  
Sediment Transport ◽  
Large Eddy Simulation ◽  
Suspended Sediment ◽  
Suspended Sediment Transport ◽  
Eddy Simulation ◽  
Large Eddy

scholarly journals LARGE-EDDY SIMULATION OF OSCILLATORY FLOW AND MORPHODYNAMICS OVER RIPPLES

2017 ◽  
pp. 23
Author(s):  
Georgios Leftheriotis ◽  
Athanassios Dimas
Keyword(s):  
Sediment Transport ◽  
Large Eddy Simulation ◽  
Oscillatory Flow ◽  
Three Dimensional ◽  
Immersed Boundary ◽  
Suspended Sediment Transport ◽  
Mean Flow ◽  
Eddy Simulation ◽  
Large Eddy ◽  
Bed Form

The objective of the present study was to study the morphodynamical development of ripples in a movable bed. The methodology is based on the coupling of fluid flow, sediment transport and morphodynamics. A well-resolved large-eddy simulation (LES) is employed for the simulation of the three-dimensional turbulent oscillatory flow and the corresponding bed and suspended sediment transport over a rippled bed. The evolution of the bed form is obtained by the numerical solution of the Exner equation based on the spanwise-mean flow and sediment transport conditions. The Immersed Boundary method is implemented for the imposition of fluid and sediment boundary conditions on the moving bed surface. Results are presented for ripple creation and propagation from a quasi-flat bed, as well as results of initially sinusoidal ripples adapting to water conditions, based on the mobility number, ψ. The numerical model demonstrates phenomena of ripple creation, propagation and migration, resulting in ripple lengths in agreement with those predicted by empirical equations. It was shown that under the same hydrodynamic forcing, the bed tends to reach the same equilibrium state, regardless of the initial bed form.

scholarly journals Large eddy simulation of sediment transport over rippled beds

2014 ◽  
Vol 1 (1) ◽  
pp. 755-801
Author(s):  
J. C. Harris ◽  
S. T. Grilli
Keyword(s):  
Sediment Transport ◽  
Large Eddy Simulation ◽  
Flow Model ◽  
Near Field ◽  
Ocean Engineering ◽  
Mean Flow ◽  
Eddy Simulation ◽  
Turbulent Statistics ◽  
Large Eddy ◽  
Wave Induced

Abstract. Wave-induced Boundary Layer (BL) flows over sandy rippled bottoms are studied using a numerical model that applies a one-way coupling of a "far-field" inviscid flow model to a "near-field" Large Eddy Simulation (LES) Navier–Stokes (NS) model. The incident inviscid velocity and pressure fields force the LES, in which near-field, wave-induced, turbulent bottom BL flows are simulated. A sediment suspension and transport model is embedded within the coupled flow model. The numerical implementation of the various models has been reported elsewhere, where we showed that the LES was able to accurately simulate both mean flow and turbulent statistics for oscillatory BL flows over a flat, rough bed. Here, we show that the model accurately predicts the mean velocity fields and suspended sediment concentration for oscillatory flows over full-scale vortex ripples. Tests show that surface roughness has a significant effect on the results. Beyond increasing our insight into wave-induced oscillatory bottom BL physics, models of sediment transport as sophisticated as the present coupled model have the potential to make quantitative predictions of sediment transport and erosion/accretion around partly buried objects in the bottom, which is important for a vast array of bottom deployed instrumentation and other practical ocean engineering problems.

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