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Fluid mixing usually involves the interplay between advection and diffusion, which together cause any initial distribution of passive scalar to homogenize and ultimately reach a uniform state. However, this scenario only holds when the…

Fluid Dynamics · Physics 2021-09-14 Jean-Luc Thiffeault

Numerical simulations for flow and transport in subsurface porous media often prove computationally prohibitive due to property data availability at multiple spatial scales that can vary by orders of magnitude. A number of model order…

Numerical Analysis · Mathematics 2018-03-13 Gurpreet Singh , Wingtat Leung , Mary F. Wheeler

We investigate the role of the correlation between a scalar quantity and the vorticity in two-dimensional mixing at infinite P\'eclet number. We assess, using a diffusivity independent mixing-norm, the dynamics of both Galerkin-truncated…

Fluid Dynamics · Physics 2024-02-27 Xi-Yuan Yin , Wesley Agoua , Tong Wu , Wouter J. T. Bos

Assortative mixing in networks is the tendency for nodes with the same attributes, or metadata, to link to each other. It is a property often found in social networks manifesting as a higher tendency of links occurring between people with…

Social and Information Networks · Computer Science 2018-04-19 Leto Peel , Jean-Charles Delvenne , Renaud Lambiotte

Diffusiophoresis, a ubiquitous phenomenon that induces particle transport whenever solute concentration gradients are present, was recently observed in the context of microsystems and shown to strongly impact colloidal transport (patterning…

The mixing effectiveness, i.e., the enhancement of molecular diffusion, of a flow can be quantified in terms of the suppression of concentration variance of a passive scalar sustained by steady sources and sinks. The mixing enhancement…

Fluid Dynamics · Physics 2009-11-13 Takahide Okabe , Bruno Eckhardt , Jean-Luc Thiffeault , Charles R. Doering

The mixing of an impurity into a flowing fluid is an important process in many areas of science, including geophysical processes, chemical reactors, and microfluidic devices. In some cases, for example periodic flows, the concepts of…

Chaotic Dynamics · Physics 2016-02-29 G. Voth , G. Haller , J. P. Gollub

We study mixing and diffusion properties of passive scalars driven by $generic$ rough shear flows. Genericity is here understood in the sense of prevalence and (ir)regularity is measured in the Besov-Nikolskii scale $B^{\alpha}_{1,…

Analysis of PDEs · Mathematics 2023-06-22 Lucio Galeati , Massimiliano Gubinelli

This paper focuses on multi-block optimization problems over transport polytopes, which underlie various applications including strongly correlated quantum physics and machine learning. Conventional block coordinate descent-type methods for…

Optimization and Control · Mathematics 2024-08-27 Yukuan Hu , Mengyu Li , Xin Liu , Cheng Meng

The need to blend observational data and mathematical models arises in many applications and leads naturally to inverse problems. Parameters appearing in the model, such as constitutive tensors, initial conditions, boundary conditions, and…

Statistics Theory · Mathematics 2010-09-16 J. Nolen , G. A. Pavliotis , A. M. Stuart

The mixing of passive scalars of decreasing diffusivity, advected in each case by the same three-dimensional Navier-Stokes turbulence, is studied. The mixing becomes more isotropic with decreasing diffusivity. The local flow in the vicinity…

Chaotic Dynamics · Physics 2009-11-10 Joerg Schumacher , Katepalli R. Sreenivasan

Numerous complex systems, both natural and artificial, are characterized by the presence of intertwined supply and/or drainage networks. Here we present a minimalist model of such co-evolving networks in a spatially continuous domain, where…

Adaptation and Self-Organizing Systems · Physics 2021-07-08 Shashank Kumar Anand , Milad Hooshyar , Jan Martin Nordbotten , Amilcare Porporato

This article introduces a new class of fast algorithms to approximate variational problems involving unbalanced optimal transport. While classical optimal transport considers only normalized probability distributions, it is important for…

Optimization and Control · Mathematics 2017-05-23 Lenaic Chizat , Gabriel Peyré , Bernhard Schmitzer , François-Xavier Vialard

The study of passive scalar transport in a turbulent velocity field leads naturally to the notion of generalized flows which are families of probability distributions on the space of solutions to the associated ODEs, which no longer satisfy…

Chaotic Dynamics · Physics 2009-10-31 Weinan E , Eric Vanden Eijnden

Recent advances in machine learning have led to the development of new methods for enhancing Monte Carlo methods such as Markov chain Monte Carlo (MCMC) and importance sampling (IS). One such method is normalizing flows, which use a neural…

Computation · Statistics 2024-01-12 Charly Andral

We consider the statistical inverse problem of estimating a background flow field (e.g., of air or water) from the partial and noisy observation of a passive scalar (e.g., the concentration of a solute), a common experimental approach to…

Numerical Analysis · Mathematics 2019-06-12 Jeff Borggaard , Nathan E. Glatt-Holtz , Justin A. Krometis

Understanding how turbulence enhances irreversible scalar mixing in density-stratified fluids is a central problem in geophysical fluid dynamics. While isotropic overturning regions are commonly the focus of mixing analyses, we here…

Fluid Dynamics · Physics 2023-04-20 Miles M. P. Couchman , Stephen M. de Bruyn Kops , Colm-cille P. Caulfield

We prove trace theorems for weighted mixed norm Sobolev spaces in the upper-half space where the weight is a power function of the vertical variable. The results show the differentiability order of the trace functions depends only on the…

Analysis of PDEs · Mathematics 2022-05-11 Tuoc Phan

We revisit the well-known problem of multiscaling in substances passively advected by homogeneous and isotropic turbulent flows or passive scalar turbulence. To that end we propose a two-parameter continuum hydrodynamic model for an…

Statistical Mechanics · Physics 2018-05-23 Tirthankar Banerjee , Abhik Basu

We consider decentralized optimization problems in which a number of agents collaborate to minimize the average of their local functions by exchanging over an underlying communication graph. Specifically, we place ourselves in an…

Optimization and Control · Mathematics 2023-03-20 Yu-Guan Hsieh , Yassine Laguel , Franck Iutzeler , Jérôme Malick