On non-isothermal flows of dilute incompressible polymeric fluids
Abstract
In the first part of the talk, after revisiting some classical models for dilute polymeric fluids, we show that thermodynamically
consistent models for non-isothermal flows of such fluids can be derived in a very elementary manner. Our approach is based on identifying the
energy storage mechanisms and entropy production mechanisms in the fluid of interest, which in turn leads to explicit formulae for the Cauchy
stress tensor and for all the fluxes involved. Having identified these mechanisms, we first derive the governing system of nonlinear partial
differential equations coupling the unsteady incompressible temperature-dependent Navier–Stokes equations with a
temperature-dependent generalization of the classical Fokker–Planck equation and an evolution equation for the internal energy. We then
illustrate the potential use of the thermodynamic basis on a rudimentary stability analysis—specifically, the finite-amplitude (nonlinear)
stability of a stationary spatially homogeneous state in a thermodynamically isolated system.
In the second part of the talk, we show that sequences of smooth solutions to the initial–boundary-value problem, which satisfy the
underlying energy/entropy estimates (and their consequences in connection with the governing system of PDEs), converge to weak
solutions that satisfy a renormalized entropy inequality. The talk is based on joint results with Miroslav Bulíček, Mark Dostalík, Vít Průša
and Endré Süli.
Local L^\infty estimates for optimal transport problems
Abstract
I will explain how to obtain local L^\infty estimates for optimal transport problems. Considering entropic optimal transport and optimal transport with p-cost, I will show how such estimates, in combination with a geometric linearisation argument, can be used in order to obtain ε-regularity statements. This is based on recent work in collaboration with M. Goldman (École Polytechnique) and R. Gvalani (ETH Zurich).
11:00
Free information geometry and the large-n limit of random matrices
Abstract
I will describe recent developments in information geometry (the study of optimal transport and entropy) for the setting of free probability. One of the main goals of free probability is to model the large-n behavior of several $n \times n$ matrices $(X_1^{(n)},\dots,X_m^{(n)})$ chosen according to a sufficiently nice joint distribution that has a similar formula for each n (for instance, a density of the form constant times $e^{-n^2 \tr_n(p(x))}$ where $p$ is a non-commutative polynomial). The limiting object is a tuple $(X_1,\dots,X_m)$ of operators from a von Neumann algebra. We want the entropy and the optimal transportation distance of the probability distributions on $n \times n$ matrix tuples converge in some sense to their free probabilistic analogs, and so to obtain a theory of Wasserstein information geometry for the free setting. I will present both negative results showing unavoidable difficulties in the free setting, and positive results showing that nonetheless several crucial aspects of information geometry do adapt.