High-velocity impact of solid objects on Non-Newtonian Fluids

We investigate which property of non-Newtonian fluids determines the deceleration of a high-speed impacting object. Using high-speed camera footage, we measure the velocity decrease of a high-speed spherical object impacting a typical Newtonian fluid (water) as a reference and compare it with a shear thickening fluid (cornstarch) and a shear thinning viscoelastic fluid (a weakly cross-linked polymer gel). Three models describing the kinetic energy loss of the object are considered: fluid inertia, shear thickening and viscoelasticity. By fitting the three models to the experimental data, we conclude that the viscoelastic model works best for both the cornstarch and the polymer gel. Since the cornstarch is also viscoelastic, we conclude that the ability to stop objects of these complex fluids is given by their viscoelasticity rather than shear thickening or shear thinning.