Finite-size Lagrangian coherent structures in a two-sided lid-driven cavity

Attractors for the motion of a finite-size particle in a two-sided lid-driven cavity

“…0.1 %. While fully resolving simulations of the fully coupled two-phase problem is computationally very expensive, attempts have been made to treat the near-wall motion of a particle or the particle-particle interaction supplementing the Maxey-Riley equation with force models (Breugem 2010;Romanò, Kunchi Kannan & Kuhlmann 2019a) based on asymptotic solutions, e.g. by Brenner (1961), dedicated numerical fits (Romanò, des Boscs & Kuhlmann 2020) or by an inelastic collision (Hofmann & Kuhlmann 2011).…”

“…Since this type of particle clustering is solely due to the particle size, Romanò, Wu & Kuhlmann (2019b) coined the term finite-size coherent structures (FSCS) for these attractors to distinguish them from the well-known Lagrangian coherent structures (LCS) which are caused by inertia (Haller 2015). Typically, FSCS form much more rapidly than inertial LCS, because the attraction rate to FSCS scales with the Reynolds number of the flow (Kuhlmann et al 2014;Muldoon & Kuhlmann 2016;Romanò et al 2019a), while the inertial attraction rate (inverse inertial time) is very small for small and nearly neutrally buoyant particles.…”

“…Here, we systematically investigate the attractors and establish accurate quantitative data on their existence range and their properties which should aid the development of improved particle-boundary interaction models like, e.g. those employed by Breugem (2010) and Romanò et al (2019a).…”

Particle accumulation in high‐Prandtl‐number liquid bridges

“…Therefore, the numerical resolution requirements are tighter, in particular, near the moving thermocapillary free surface. To avoid estimating ∆, we employ a more physically-based PBI model which makes use of the lubrication-induced drag acting on the particle in direction normal to the boundary [4]. For an accurate modeling, however, the only parameter ∆ of the collision model, depending on particle size, density and flow parameters, should be determined carefully [2].…”

Reconstructing the fluid flow by tracking of large particles

“…In fact, there are technological limitations in accurately tracking very small particles, and the smaller the particle, the harder and inaccurate the tracking. Thereafter, particleboundary interactions strongly inuence the particle trajectories at distance O(a p ) from the boundary [31,32]. As a result, near a wall or a free surface, the particle velocity remarkably deviates from the velocity of the uid.…”