Simulation of particle deposition in bubbly flows using an Eulerian–Lagrangian framework

An Eulerian–Lagrangian simulation framework is developed to investigate particle deposition across gas–liquid interfaces in bubbly flows as relevant to pool scrubbing, i.e., the removal of aerosol particles by forcing a gas stream through a water pool. The carrier flow is resolved with a Volume-of-Fluid formulation of the incompressible Navier–Stokes equations, while dispersed particles are tracked in a Lagrangian manner including hydrodynamic and Brownian forces. Particular emphasis is placed on a newly developed capillary force model for finite-sized particles passing through a deformable interface at large bubble–particle scale separation. The model is based on a contact angle dependent capillary force formulation, and is embedded consistently in the mathematical description using the distance between the particle and the constructed interface. The methodology is applied to a single rising bubble and to a polydisperse bubbly flow subject to coalescence and breakup. Trajectory-averaged probability density functions of curvature, pressure gradient, and the coherent-structure function are evaluated separately for deposited and non-deposited particles. We found that deposition is most likely to occur in concave interface regions and in strain-dominated flow. Variations of bubble size and particle properties demonstrate that deposition efficiency increases with bubble diameter and particle inertia, while the favorable flow regions of deposition remain qualitatively unchanged. In the polydisperse bubbly flow, the interface morphology is modified by coalescence and breakup, but the tendency for particles to deposit in strain-dominated regions persists. • Eulerian-Lagrangian VOF-LPT framework for aerosol deposition in bubbly flows. • New geometrically motivated capillary force model for Lagrangian Point Particles. • Deposition analysis based on curvature, pressure gradient and coherent structures. • Deposition favored in concave/low-curvature regions and strain-dominated flow.