Abstract
The capture of neutrally buoyant, sub-Kolmogorov particles at the interface of deformable drops in turbulent flow and the subsequent evolution of particle surface distribution are investigated. Direct numerical simulation of turbulence, phase-field modelling of the drop interface dynamics and Lagrangian particle tracking are used. Particle distribution is obtained considering excluded-volume interactions, i.e. by enforcing particle collisions. Particles are initially dispersed in the carrier flow and are driven in time towards the surface of the drops by jet-like turbulent fluid motions. Once captured by the interfacial forces, particles disperse on the surface. Excluded-volume interactions bring particles into long-term trapping regions where the average surface velocity divergence sampled by the particles is zero. These regions correlate well with portions of the interface characterized by higher-than-mean curvature, indicating that modifications of the surface tension induced by the presence of very small particles will be stronger in the highly convex regions of the interface.
Highlights
The process of particle capture and subsequent trapping on the surface of deformable drops in turbulence may have important consequences on surface properties
In this work, we examine the dynamics of small neutrally buoyant particles trapped at the interface of large deformable drops in turbulent channel flow
The inset shows the p.d.f.s computed at study is to pave the way for accurate simulations of three-phase flows, in which local modifications of the interface surface tension produced by concentrated particle patterns can be accurately accounted for
Summary
The process of particle capture and subsequent trapping on the surface of deformable drops in turbulence may have important consequences on surface properties. Particles are expected to act in a way similar to soluble surfactant molecules, affecting surface tension in particular (Binks 2002; Soligo, Roccon & Soldati 2019b; Wang & Brito-Parada 2021). This has important consequences at the macroscale, influencing drop deformability and coalescence and breakup processes. We investigated recently the process of particle removal by deformable drops (Hajisharifi, Marchioli & Soldati 2021), showing that particles are transported towards the interface by jet-like turbulent motions and, once close enough, are captured by interfacial forces in regions of local flow expansion characterized by positive velocity divergence. We correlate particle clusters with the local interface curvature, in view of the potential modulation that trapped particles may produce on the surface tension and, on the drop deformability
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
