Lift and drag forces acting on a particle moving with zero slip in a linear shear flow near a wall

Abstract

Abstract

Lift and drag forces acting on a particle moving in the presence of slip and shear near a wall

“…with the lift normalised by the slip Reynolds number. The outer-region-based lift model given by (2.16) performs well for small and intermediate 1 Shi & Rzehak 2020), however, it is worth noting that this model predicts a zero lift force in the absence of slip which is not the case for non-zero shear rates (Ekanayake et al 2020).…”

“…Asymptotic studies for Re γ 1 (Asmolov 1999) and DNS studies for 10 −3 < Re γ < 10 −1 (Ekanayake et al 2020) find a lift force that decays rapidly to zero with increasing separation distance. Based on numerical lift results, Ekanayake et al (2020) proposed an outer-region-based lift model accounting for both shear and wall effects…”

“…The available correlations for C wb,in L,2 and C wb,in L,3 are summarised in table 4. Correlations available for C wb,in L,1 are tabulated in our previous study (Ekanayake et al 2020) and hence not detailed further here.…”

“…In this study, we are particularly interested in the lift forces acting on smooth, rigid spherical particles that are moving with a finite slip velocity and at low particle Reynolds numbers. Note that this study is an extension of our previous work, which investigates the lift and drag force in the presence of shear, but without slip velocity (Ekanayake et al 2020). In dilute systems, particle slip velocities can originate from a variety of forces, including fluid drag or buoyancy.…”

“…These forces are often much higher in magnitude than the lift forces. For example, freely translating neutrally buoyant particles experience a finite but relatively small slip velocity due to the wall-shear fluid drag force (Ekanayake et al 2020). In contrast, heavy particles sedimenting in vertical flows can experience much larger slip velocities due to strong buoyancy forces, which are further affected by wall-bounded fluid drag forces when particles are moving in close proximity to a wall.…”