An Experimental Study on the Impact of Wormlike Micellar Droplets onto Solid Surfaces

The present study investigates the impact of wormlike micellar droplets on dry solid horizontal surfaces experimentally. Here, the wormlike micellar sample is an aqueous solution of Cetyltrimethylammonium bromide (CTAB) and Potassium bromide (KBr). The effects of impact speed, surface roughness, and the viscosity and elasticity of the liquid phase on the spreading and receding of the droplet are studied in detail. The droplets are formed via 14G and 16G needles and the speed of impact is in the range of 2–3 m/s. The solid surfaces are plates of plexiglass and stainless steel. The results are compared with the impact of equivalent Newtonian droplets to investigate the effect of rheological properties. It is found that fluid elasticity causes a decrease in the spreading and an increase in the receding of droplets. The stress analysis suggests that this normal force is primarily a result of elongational viscosity, while the influence of the first normal stress difference on these dynamics is minimal.