Abstract
A gravity current in a channel at the presence of a triangular obstacle was investigated using LES simulation and the Eulerian approach. The Saffman–Mei equation was also applied to examine the effect of shear-induced lift force on particle deposition. To this end, particles were considered as Lagrangian markers and injected into gravity current. It is important to keep in mind that the interaction between the gravity current and particles was treated as a one-way coupling. The results show that shear-induced lift force prevents particles to deposit at the entrance of channel, where the velocity gradient is high. Furthermore, a reduction in the rate of sediment deposition can be seen again in the vicinity of obstacle due to high velocity gradient. The important result is that the shear-induced lift force has an important role in the cases with considerable velocity gradient in quasi-steady flows and this force can affect the pattern of sedimentation over time. Q criterion is utilized to depict the vortical structures of flow. Vortical structures with larger diameter, that indicate stronger vortexes, has been seen in various sections of channel, especially in the region near the obstacle due to the presence of obstacle.
Highlights
A gravity current in a channel at the presence of a triangular obstacle was investigated using Large Eddy Simulation (LES) simulation and the Eulerian approach
The Eulerian approach and LES model were employed to simulate turbulent gravity current, and Lagrangian markers were injected into the flow to explore the behavior of particles in the deposition process and to investigate the effect of shear-induced lift force on the sedimentation
The results showed that shear-induced lift force prevented particles from depositing at the channel entrance, in high-vorticity regions
Summary
A gravity current in a channel at the presence of a triangular obstacle was investigated using LES simulation and the Eulerian approach. The Saffman–Mei equation was applied to examine the effect of shear-induced lift force on particle deposition To this end, particles were considered as Lagrangian markers and injected into gravity current. The results show that shear-induced lift force prevents particles to deposit at the entrance of channel, where the velocity gradient is high. Continuous particle-driven gravity currents frequently occur in natural settings for instance, seafloor turbidity currents, discharge of particles to the ocean by particle-laden rivers and lava flows[5,6,7,8,9,10] and in industrial settings for example in the oil and gas industry and water treatment facilities[11] They play an important role in the transport of sediments in oceans or lakes[12]. It is worth noting that a stochastic dispersion method was adopted for applying velocity fluctuations generated by small eddies (unresolved turbulence) on the particles to better predict the particle dispersion in LES of a turbulent flow
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