Water and honey are Newtonian fluids; that means their viscosity (resistance to flow) is independent of the applied force. However, this is not true for many fluids we interact with daily such as toothpaste, ketchup and hair gel. These fluids are called non-Newtonian because their viscosity varies greatly with applied force, and this can lead to dramatic changes in their flow behavior. We study drops of non-Newtonian fluid impacting solid surfaces at high speeds thus experiencing high forces. A drop impact lasts only a few milliseconds, so to capture this behavior we use high-speed cameras that can film the impact at over 100,000 frames per second. We observe a multitude of flow behaviors depending on the speed that the drop hits the surface: smooth spreading, bouncing like a ball, and everything in between. Looking at these impacting drops, one can learn about the flow behavior at very high flow rates.
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