Effects of viscoelasticity on drop impact and spreading on a solid surface

Abstract

The effects of viscoelasticity on drop impact and spreading on a flat solid surface are studied computationally using a finite-difference-front-tracking method. The finitely extensible nonlinear elastic-Chilcott-Rallison model is used to account for the fluid viscoelasticity. It is found that viscoelasticity favors advancement of contact line during the spreading phase, leading to a slight increase in the maximum spreading, in agreement with experimental observations [Huh, Jung, Seo, and Lee, Microfluid. Nanofluid. 18, 1221 (2015)]. However, in contrast with the well-known antirebound effects of polymeric additives, the viscoelasticity is found to enhance the tendency of the drop rebound in the receding phase. These results suggest that the antirebound effects are mainly due to the polymer-induced modification of wetting properties of the substrate rather than the change in the material properties of the drop fluid. A model is proposed to test this hypothesis. It is found that the model results in good qualitative agreement with the experimental observations and the antirebound behavior can be captured by the modification of surface wetting properties in the receding phase.

Interfacial dynamics of thin viscoelastic films and drops

“…In particular, Seemann et al [52] also show that viscoelastic effects tend to stabilize the observed undulations, in agreement with our results. In addition, our simulations suggest that viscoelasticity enhances spreading, consistently with findings in [35,51]. We note that, Spaid and Homsy [51] observe that the viscoelastic fluid interface tends to be stabilized primarily because of changes of transport of momentum in the spreading direction, and finite restoring forces that are present when a viscoelastic fluid is stretched.…”

“…Our numerical results show that viscoelasticity enhances the spreading in the early stage of wetting by smoothing the interface in the contact line region. Similar considerations are drawn by Wang et al [34], and Izbassarov and Muradoglu [35]. Finally, the study of the advancing dynamic contact angle allows us to determine that the Cox-Voinov law [36,37] holds for the viscous Newtonian fluid, but not for the viscoelastic counterpart.…”

“…We note that, Spaid and Homsy [51] observe that the viscoelastic fluid interface tends to be stabilized primarily because of changes of transport of momentum in the spreading direction, and finite restoring forces that are present when a viscoelastic fluid is stretched. More recently, Izbassarov and Muradoglu [35] consistently demonstrate that the enhancement of the spreading of viscoelastic drops is mainly due to the stretched polymer chains that exert an extensional stress, pushing the contact line, and thus increasing the spreading rate.…”

Computational modeling of multiphase viscoelastic and elastoviscoplastic flows

“…Multiphase viscoelastic (EV) fluid flows have been studied much more than EVP flows, and indeed some of the results in literature will be used to validate our numerical implementation. To give a few examples of such studies, we list 2D and 3D direct numerical simulations of the dynamics of a rigid single particle, [31][32][33][34][35] two particles, [36][37][38][39] multiple particles, [40][41][42][43] as well as droplets in viscoelastic two-phase flow systems in which one or both phases could be viscoelastic, [44][45][46] including the case of soft particles modeled as a neo-Hookean solid (ie, a deformable particle is assumed to be a viscoelastic fluid with an infinite relaxation time). 47,48 In the case of a pure visco-plastic (VP) suspending fluid, there is an abundance of computational studies of single and multiple particles.…”

An adaptive solver for viscoelastic incompressible two-phase problems applied to the study of the splashing of weakly viscoelastic droplets

“…This numerical result agrees well with the experimental results of [60] where the wettability of the fluids (with and without polymers) is so high that the contact angle is not longer a relevant parameter and the spreading of the droplet is unaffected by the presence of polymers. This is not the general case since the substrate will play a relevant (non simple) role in the spreading and receding stages as the dynamic contact angle will vary in the process [50,49].…”