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Fluid mechanics in phase change and liquid impact on nanoengineered surfaces

Manish K Tiwari

Nanoengineered Systems Laboratory, UCL Mechanical Engineering, London, WC1E 7JE, UK

Drop-solid interactions play an important role in nature and in a large number of technological applications. In this presentation, I will aim at illustrating the role of solid surface morphology and wettability in these interactions. To start with, I will discuss how surface nanotexture plays an important role in helping to alter and engineer surface wettability to extremes and to achieve superhydrophobic surfaces. Next, I will share some insights into potential applications of such surfaces in altering and manipulating phase change of water, with a specific example of freezing of water droplets on surfaces in so called supercooled conditions. Next, I will share some insights into how to design the superhydrophobic surfaces to sustain impalement by impacting liquid droplets both at room temperature and under supercooled conditions. Finally, I will show some results on new designs of superhydrophobic surfaces which also exploit material flexibility to enhance the liquid impalement resistance. Recent results on impact of high-Weber number (>10,000), turbulent jets will be used to discuss the potential use of such surfaces as coatings in applications ranging from aerospace industry to infrastructure components.

Selected relevant publications

1. C. Peng, Z. Chen, M. K. Tiwari, “All-organic superhydrophobic coatings with mechanochemical robustness and liquid impalement resistance,” 17:355–360, Nature Materials, 2018.

2. T. Maitra, M. K. Tiwari, C. Antonini, P. Schoch, S. Jung., P. Eberle, Poulikakos, D. “On the Nanoengineering of Superhydrophobic and Impalement Resistant Surface Textures below the Freezing Temperature,” 14:172-182, Nano Letters, 2014.

3. D. Torresin, M. K. Tiwari, D. Del Col, D. Poulikakos, “Flow condensation on copper based nanotextured superhydrophobic surfaces,” 29 (2): 840–848, Langmuir, 2013.

4. S. Jung, M. K. Tiwari, N. V. Doan and D. Poulikakos, “Mechanism of supercooled droplet freezing on surfaces,” 3:615, DOI:10.1038/ncomms1630, Nature Communications, 2012.