Droplet dynamics in sub-critical eccentric flows

In this study single droplet dynamics for a Newtonian droplet in a Newtonian matrix have been observed in a controlled complex flow field. The mixed flow conditions, i.e. a combination of shear and extension, were applied using a newly designed eccentric cylinder device, and deforming droplets were visualised using optical microscopy. The experimental results on droplet deformation and orientation are compared with the predictions of the phenomenological Maffetone-Minale model. The model predictions are obtained by using the transient form of the model and incorporating a flow type parameter that accounts for the relative amount of shear and elongational effects. For all the sub-critical flows considered here, good agreement was found between the model predictions and the experimental data.