Abstract: Roughness-based superhydrophobic and superhydrophilic surfaces have been
extensively studied for more than two decades. The early focus was to mimic nature,
e.g. lotus leaves, to produce low-drag and/or self-cleaning surfaces. Through the past
decade or more, the focus has also been on manipulating phases of (say) water on
surfaces. Specific interest has been in applications such as boiling and condensation heat
transfer, anti-icing/anti-frosting, water harvesting, among others. Through the years, we
have organized the interrogation of this area based on equilibrium and non-equilibrium
thermodynamic (and fluid dynamics) analyses corresponding to three pairs of phase
changes (with two permutations each) – liquid-vapor, solid-liquid, and vapor-solid. Using
such analyses, three foundational questions will be addressed in this talk:
1. How to eliminate Leidenfrost (vapor) film collapse and thus entirely change the boiling curve?
2.What non-dimensional number fundamentally characterizes Leidenfrost (vapor) film
collapse in boiling heat transfer (and liquid-film collapse in condensation heat transfer)?
3. What is the interface temperature during “far” from equilibrium phase change?

Bio: Neelesh Patankar received his BS (B.Tech.) in Mechanical Engineering from the
Indian Institute of Technology, Bombay (1993) and his doctorate in Mechanical
Engineering from the University of Pennsylvania (1997). Following his Ph.D., he was a
post-doctoral associate with Prof. Daniel D. Joseph at the University of Minnesota until
2000. He joined the Department of Mechanical Engineering at Northwestern University
in 2000 where is currently a Professor. Neelesh is a Fellow of the American Physical
Society. He has received the NSF CAREER award, the International Conference on
Multiphase Flow’s Junior Award, and has been selected to the Defense Science Study
Group. Neelesh has been on the Editorial Boards of the Journal of Computational
Physics, ASME Journal of Fluids Engineering, and Scientific Reports. He has also received
several university-wide teaching awards at Northwestern University including Charles
Deering McCormick Teaching Professorship.

Neelesh Patankar flyer