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

Area of Science:

• Fluid dynamics
• Rheology
• Materials science

Background:

• Non-Newtonian fluids exhibit complex behaviors like shear thickening and thinning.
• Understanding the deceleration of impacting objects in these fluids is critical for various applications.

Purpose of the Study:

• To determine the primary property responsible for decelerating high-speed objects impacting non-Newtonian fluids.
• To compare the effectiveness of fluid inertia, shear thickening, and viscoelasticity models in explaining kinetic energy loss.

Main Methods:

• High-speed impact experiments using a spherical object.
• Comparison of fluid behavior in water (Newtonian), cornstarch (shear thickening), and polymer gel (shear thinning viscoelastic).
• Analysis of object velocity decrease and fitting of kinetic energy loss models.

Main Results:

• Viscoelasticity was found to be the dominant factor in object deceleration for both cornstarch and polymer gel.
• The viscoelastic model provided the best fit to experimental data for complex fluids.
• Cornstarch, despite being shear thickening, demonstrated behavior primarily governed by viscoelasticity.

Conclusions:

• Viscoelasticity, rather than shear thickening or thinning, dictates the stopping power of complex non-Newtonian fluids for impacting objects.
• This research clarifies the dominant rheological property governing impact dynamics in non-Newtonian fluids.