Study of the effect of elastic properties on non-Newtonian drop motion in inertia regime

In this paper, steady motion of non-Newtonian falling drop through a Newtonian fluid at low Reynolds number is investigated analytically. Here, the Upper Convected Maxwell model (UCM) is used for drop phase and Newtonian model is considered for external fluid. During the past few decades, studies relating to non-Newtonian instabilities especially those involving free surfaces are amongst the most striking. These types of studies can be used to optimize design processes in, for example, the petroleum and medicine related processes, metal extraction, and paint and power-plant related fields. Analytical solution is obtained using the perturbation method. Reynolds and Deborah numbers are used to linearize the equations governing the problem in analytical method. Deborah number indicates the elastic effect of drop. The drag force increases by the growth of the elastic effect of non-Newtonian Drop’s. The non-Newtonian drop loses its shape and exchanges to an oblate form. Increment in Deborah number enhances the dimple at the bottom of the drop and results in an increment in its drag force and as a consequence its terminal velocity decreases. A hole is created at the rear of the drop due to the presence of inertia force and focus of normal component of stress at the rear of the drop. The novelty of this study is to consider the convection (non-linear) term of the momentum equations which was neglected in the previous studies due to the creeping flow.