Droplet deformation under simple shear investigated by experiment, numerical simulation and modeling

The deformation and break-up of droplets in complex flow fields is encountered in many engineering applications such as mixing and dispersing processes. To manipulate and control such operations, rheological, interfacial and dynamical properties of the multiphase fluid as well as their interaction have to be known. In the present work, the deformation of droplets is studied experimentally in simple shear flow and compared with numerical calculations and modeling. For this purpose, a computer-controlled parallel band apparatus equipped with a digital camera records the time evolution of the sheared droplet and thus, analyzes digitally its shape. Numerical simulations are performed to calculate the drop deformation in three-dimensional space, although only two dimensions available experimentally (plane of shear) are considered for comparison. The simulations use a boundary integral method to determine drop deformation from the mass and momentum balance equations. Furthermore, a simple phenomenological model in terms of a droplet shape tensor is proposed to describe droplet deformation in homogeneous flow.