FLOW Paper published in PRL (August 2017)
The paper ‘Bifurcation Dynamics of a Particle-Encapsulating Droplet in Shear Flow’ by Lailai Zhu and François Gallaire has been published in Physical Review Letters. The research numerically investigates the dynamics of a model system (in creeping flow) mimicking nucleated cells and double-emulsions, etc. Despite the inertialess regime, instabilities and bifurcations were observed, and interpreted by a dynamic system approach commonly used for hydrodynamic instabilities. The work was initiated by Lailai as a postdoc in the LFMI group at EPFL and finalized as a KTH employee visiting Princeton University.
To understand the behavior of composite fluid particles such as nucleated cells and double emulsions in flow, we study a finite-size particle encapsulated in a deforming droplet under shear flow as a model system. In addition to its concentric particle-droplet configuration, we numerically explore other eccentric and time-periodic equilibrium solutions, which emerge spontaneously via supercritical pitchfork and Hopf bifurcations. We present the loci of these solutions around the codimension-two point. We adopt a dynamic system approach to model and characterize the coupled behavior of the two bifurcations. By exploring the flow fields and hydrodynamic forces in detail, we identify the role of hydrodynamic particle-droplet interaction which gives rise to these bifurcations.