Dynamic wetting of Boger fluids

Impact of fluid memory on wetting approaching the air entrainment limit

“…1(b) is an image at the highest Ca we have achieved and shows that the interface is approaching the point where air will be entrained. For lower Ca, they are virtually identical [2]. For Ca = 0.33, the Wi based on the capillary length for the Boger fluid is 1.2.…”

“…Details may be found in Refs. [1,2,23,24]. Images of the Boger fluid at two different values of Ca are shown in Fig.…”

“…The situation is less clear for fluids with memory. In an earlier paper, we showed that elasticity has little impact on dynamic wetting for capillary numbers (Ca = g 0 U/r, where g 0 is the viscosity, U is the contact line speed, and r is the surface tension) below 0.01 [2]. In this note, we extend those measurements to higher Ca and Weissenberg numbers (Wi = k B U/a, where k B is the relaxation time of fluid and a is an appropriate length scale, often chosen as the capillary length a ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ffi r=ðqgÞ p in wetting problems) where we approach air entrainment [17].…”

“…Thus, one might expect non-Newtonian fluids to have dynamic wetting properties different from those of Newtonian fluids. We [1,2] and others [3][4][5][6][7][8][9][10][11][12][13][14][15][16] have considered such effects. For shear thinning fluids, the situation is rather clear: shear thinning reduces the viscous drag of the solid on the fluid near the contact line and therefore decreases viscous effects on wetting [1].…”

Wetting kinetics of polymer solutions and force‐based contact angles

“…Barone 10 and Rafa€ ı et al 11 verified both these results experimentally but in a later article Rafa€ ı and Bonn 12 suggested that the elasticity had some role. Wei et al 13,14 found little effect of elasticity on dynamic contact angles.…”