Mechanical and Civil Engineering Seminar

Mechanical and Civil Engineering Seminar Series

Title: How "to see a world in a grain of sand"?

Abstract: To illustrate this William Blake's quote from Auguries of Innocence, I will discuss granular media and water near the contact line – two states of matter that are largely misunderstood due to ad hoc modeling, but nevertheless admitting a systematic analysis with theoretical physics tools.

First, building on a problem offered at one of physics olympiads, we develop thermodynamics and rheology of a granular pile in the gravity field, which proves to be anything but ordinary. In particular, we show that a pile is characterized by three temperatures: one is infinite, the other is negative, and the third is of second order rarely encountered in physical systems. Also, an adequate rheological description turned out to be instrumental for coherent understanding of granular media thermodynamics.

Second, in an effort to rigorously resolve the Huh-Scriven paradox of singular stresses at the moving contact line, we apply the Lifshitz theory of van der Waals forces to a wedge of a dielectric material. We demonstrate that near the contact line, due to increasingly dominant effects of vacuum polarization, the quantum fluctuations make water behave very differently from its normal state assumed in the traditional fluid-mechanics treatment of the problem and, instead, act more like a grain of sand.

Bio: Dr. Rouslan Krechetnikov (Ph.D. 2004, Moscow Institute of Physics and Technology) is a Professor of Mathematics. Prior to rejoining the University of Alberta as a tenured Associate Professor, he was an Assistant Professor of Mechanical Engineering at UCSB (2009-2013), and spent a year (2007-2008) as an Assistant Professor of Mathematics at the University of Alberta (Edmonton, Canada) and a year (2006-2007) at Carleton University (Ottawa, Canada). Dr. Krechetnikov was also a Postdoctoral Fellow at Caltech (2004-2006) with Jerry Marsden and UCSB (2002-2004) with Bud Homsy. Visiting positions were held at UCSB (2013-2015) and Caltech (2008-2009, 2023-present).

Dr. Krechetnikov combines theory and experiment in studying problems of mechanics and fluid dynamics at all scales. His work has been recognized by a number of honors and awards, among which are NSF CAREER (2011), DARPA Young Faculty Award (2011), Ig Nobel (2012), Presidential Early Career Award for Scientists and Engineers (2014), and Research Fellowship at the University of Alberta (2015-2020).

NOTE: At this time, in-person Mechanical and Civil Engineering Lectures are open to all Caltech students/staff/faculty/visitors.