Prediction of particles deposition in a dilute quasi-steady gravity current by Lagrangian markers: effect of shear-induced lift force

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.

Turbidity currents propagating down an inclined slope: particle auto-suspension

“…At t > 6 (figure 7c-f ), the small vortex structures in the near-wall region behind the current gradually decline and disappear as a result of dissipation. In addition, the streamwise development of the coherent vortical structures here is limited due to the small Re, and the flow is mainly engaged by the transverse vortical structures, agreeing with the understandings of Nasr-Azadani & Meiburg (2014) and Koohandaz et al (2020).…”

“…The fragmented vortical structures are found in the near-wall region and the mixing layer inside the front vortex. These vortical structures are a manifestation of the combined effects of a complex fluid dynamics with the no-slip condition on the bed (Koohandaz et al 2020) and the interaction of particle groups with fluids. In the near-wall region, the height of this vortex structure is generally limited to approximately 0.5 dimensionless lengths due to the particle transport along the way in the middle layers, and is limited by the upper interface of the TC.…”

“…2020; Koohandaz et al. 2020; Pelmard, Norris & Friedrich 2018). In recent years, the coupled model of solving individual particle motion with the discrete element method (DEM) and fluid motion has been widely used to simulate two-phase flows, such as Schmeeckle (2014), Sun & Xiao (2016), Jing et al.…”

“…The advantage of DNS is that it can provide more accurate results prior to the other two methods, but it requires a lot of computational resources. By comparison, LES gives relatively satisfactory results with less computational cost, which makes it widely adopted (Kyrousi et al 2018;Goodarzi et al 2020;Koohandaz et al 2020;Pelmard, Norris & Friedrich 2018). In recent years, the coupled model of solving individual particle motion with the discrete element method (DEM) and fluid motion has been widely used to simulate two-phase flows, such as Schmeeckle (2014), Sun & Xiao (2016), Jing et al (2016), Maurin, Chauchat & Frey (2018), Pähtz & Durán (2018a), Pähtz & Durán (2018b), Pähtz & Durán (2020) and Zhu et al (2020).…”

Emission Characteristics of Formaldehyde and Particulate Matter in Side-Stream Smoke Emitted from Cigarettes in an Environmental Chamber

“…In addition, the fitting result of particulate matter is worse than that of formaldehyde, especially during the rise period. This reason is that the burning of cigarettes causes drastic changes in the temperature and humidity of the surrounding environment affecting the diffusion and condensation of particulate matter [30][31][32].…”