The Warren K. Lewis Lectureship in Chemical Engineering – 2021

Short Stories in Fluid Dynamics at Different Length Scales

(1) Speech and Spreading of a Pathogen, (2) Thin Films and a Novel Similarity Solution, and (3) Nanoscale Capillary Instabilities and Molecular Biology

Howard A. Stone, Ph.D.
Department Chair and Donald R. Dixon ’69 and Elizabeth W. Dixon Professor in Mechanical and Aerospace Engineering
Princeton University

Thursday, May 6, 2021
12:00 p.m.

Virtual Event – Zoom Link



Many modern research themes in science and engineering introduce new questions, some of which can be at least partially understood using fundamental concepts. We will provide several examples of our recent research combining experiments and theory at different length scales, from large to small.

In the first example, we will illustrate how features of speech create flow structures capable of efficient transport of a pathogen, e.g., a virus, over distances exceeding 1-2 m. This situation is relevant to airborne disease transmission by asymptotic individuals.

In a second example at the scale of centimeters and smaller, we will document experimentally the time and (three-dimensional) space variations of the shape of a falling film near the edge of a vertical plate and rationalize the quantitative features using a similarity solution. This example seems particularly unusual since we are able to theoretically show that the shape is described by a nonlinear partial differential equation, involving three independent variables, yet the equation can be reduced by a similarity transformation to a nonlinear ordinary differential equation.

As a final example, but now at the nanoscale, we discuss the formation of the spindle in a dividing cell, and report experiments documenting a condensed protein phase on growing microtubules, which is followed by the Rayleigh-Plateau instability. The discrete droplets along a microtubule then drive branching nucleation, which we rationalize mechanistically using kinetic simulations


Professor Howard Stone received the B.S. Degree in Chemical Engineering from UC Davis in 1982 and the PhD in Chemical Engineering from Caltech in 1988. Following a postdoctoral fellowship at the University of Cambridge, in 1989 Howard joined the faculty of the (now) School of Engineering and Applied Sciences at Harvard University, where he eventually became the Vicky Joseph Professor of Engineering and Applied Mathematics. In July 2009 Howard moved to Princeton University where he is Department Chair and Donald R. Dixon ’69 and Elizabeth W. Dixon Professor in Mechanical and Aerospace Engineering.

Professor Stone’s research interests are in fluid dynamics, especially as they arise in research and applications at the interface of engineering, chemistry, physics, and biology. He is a Fellow of the American Physical Society (APS), and is past Chair of the Division of Fluid Dynamics of the APS. Currently he is on the editorial or advisory boards of Physical Review Fluids, Langmuir, and Soft Matter, and is co-editor of the Soft Matter Book Series. He received the 2016 Fluid Dynamics Prize given by the APS and is the first recipient of the G.K. Batchelor Prize in Fluid Dynamics (2008). He was elected to the National Academy of Engineering in 2009, the American Academy of Arts and Sciences in 2011, and the National Academy of Sciences in 2014.