Interaction between particle clusters and particle-induced turbulence

Performance of Various Fluid-Solid Coupling Methods for DNS of Particulate Flow

“…From figure 5 we can see that during the initial phase the average sedimentation velocity reaches a minimum (wherew/u ref ≈ 2.6) and then levels out to approximatelyw/u ref = 2. This is a manifestation of a strong wake-sheltering effect as already observed in [5]. Obviously, the minimum is not observed in the case of a single sedimenting sphere.…”

“…The boundary conditions are: uniform velocity at the inflow and along the top and bottom boundaries; convective condition at the outflow. [5], implemented into the present solver as described in [2]. Figure 1 shows that the temporal variation of the drag follows a reasonably smooth periodic curve when using the current scheme.…”

“…The same goes for the lift force which has been omitted. On the other hand, the method of Kajishima and Takiguchi [5], implemented as shown in [2], yields significant oscillations on the time-scale of the mesh-width divided by the cylinder velocity. In other words, the smoothing provided by the present method proves more efficient in hiding the influence of the fixed grid.…”

“…Here we consider a similar case as the one studied in reference [5]. A large number of particles are sedimenting in a tri-periodic domain.…”

“…In reference [5] the artificial force term is instead weighted by the solid fraction of the surrounding grid cell, providing some amount of smoothing. However, the resulting drag/lift variation obtained in our computations with this method still shows substantial grid-induced oscillations (see results in § 3.1).…”