Fast Imaging Technique to Study Drop Impact Dynamics of Non-Newtonian Fluids |
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Authors: | Qin Xu Ivo Peters Sam Wilken Eric Brown Heinrich Jaeger |
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Institution: | 1.Department of Physics, The University of Chicago;2.James Franck Institute, The University of Chicago;3.Department of Mechanical Engineering and Materials Science, Yale University |
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Abstract: | In the field of fluid mechanics, many dynamical processes not only occur over a very short time interval but also require high spatial resolution for detailed observation, scenarios that make it challenging to observe with conventional imaging systems. One of these is the drop impact of liquids, which usually happens within one tenth of millisecond. To tackle this challenge, a fast imaging technique is introduced that combines a high-speed camera (capable of up to one million frames per second) with a macro lens with long working distance to bring the spatial resolution of the image down to 10 µm/pixel. The imaging technique enables precise measurement of relevant fluid dynamic quantities, such as the flow field, the spreading distance and the splashing speed, from analysis of the recorded video. To demonstrate the capabilities of this visualization system, the impact dynamics when droplets of non-Newtonian fluids impinge on a flat hard surface are characterized. Two situations are considered: for oxidized liquid metal droplets we focus on the spreading behavior, and for densely packed suspensions we determine the onset of splashing. More generally, the combination of high temporal and spatial imaging resolution introduced here offers advantages for studying fast dynamics across a wide range of microscale phenomena. |
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Keywords: | Physics Issue 85 fluid mechanics fast camera dense suspension liquid metal drop impact splashing |
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