Seminars and Colloquia
Physics
Patterned Flows: from Thin Films to Turbulence
Mon, Feb 04, 2019,
11:00 AM
at Seminar Hall 31, 2nd Floor, Main Building
Dr. Jason Picardo
ICTS, Bangalore
Abstract :
Many fluid dynamic problems in nature and industry are nonlinear and give rise
to spatio-temporal patterns. Indeed, these patterns contribute to the beauty and
fascination of the subject; they also impact transport rates and other macroscopic physical properties. In the course of this talk, we will encounter two very different kinds of patterns: (a) interfacial patterns that arise from the instability of thin liquid films, and (b) vortical flow structures that characterise the small-scales of turbulent flows. In the first part of the talk, I shall revisit the oldest paradigm of pattern formation, first propounded by Rayleigh, which asserts that the length-scale of an interfacial pattern is determined by the fastest growing linear instability mode. By way of a model problem, I will demonstrate a clear counter-example to this paradigm and shed light on the role of nonlinearity in patterning fluid interfaces. The second half of the talk will focus on the transport of model elastic filaments (bead-spring chains) by a turbulent flow. Here, we shall see that contrary to our expectation of uniform mixing, the filaments actually show a preferential sampling of vortical regions in the flow. Some exciting new questions raised by these results will also be discussed.
