Single Drop Impacts of Complex Fluids: A Review - Drops and Bubbles in Contact with Solid Surfaces - page 282

Figure 12. Comparison between the fluid velocity measured inside liquid droplets impacting on hy-
drophobic surfaces and the contact line velocity during the recoil phase [44].
Figure 13. Tentative model for the dissipative force arising at the contact line during drop retraction: as
the meniscus recedes, polymer molecules accumulating in the liquid wedge are stretched by molecular
combing.
the horizontal component of the surface force driving the droplet retraction must be
larger than in a Newtonian fluid, therefore the apparent dynamic contact angle must
be smaller.