Cellular mixing with bounded palenstrophy

Crippa, Gianluca and Schulze, Christian. (2017) Cellular mixing with bounded palenstrophy. Mathematical Models and Methods in Applied Sciences, 27 (12). pp. 2297-2320.

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Official URL: http://edoc.unibas.ch/58739/

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We study the problem of optimal mixing of a passive scalar ρ advected by an incom- pressible flow on the two dimensional unit square. The scalar ρ solves the continuity equation with a divergence-free velocity field u with uniform-in-time bounds on the homogeneous Sobolev semi-norm W ̇ s,p , where s > 1 and 1 < p ≤ ∞ . We measure the degree of mixedness of the tracer ρ via the two different notions of mixing scale commonly used in this setting, namely the functional and the geometric mixing scale. For velocity fields with the above constraint, it is known that the decay of both mixing scales cannot be faster than exponential . Numerical simulations suggest that this exponential lower bound is in fact sharp, but so far there is no explicit analytical example which matches this result. We analyze velocity fields of cellular type , which is a special localized structure often used in constructions of explicit analytical examples of mixing flows and can be viewed as a generalization of the self-similar construction by Alberti, Crippa and Mazzucato [2]. We show that for any velocity field of cellular type both mixing scales cannot decay faster than polynomially .
Faculties and Departments:05 Faculty of Science > Departement Mathematik und Informatik > Mathematik > Analysis (Crippa)
UniBasel Contributors:Crippa, Gianluca and Schulze, Christian
Item Type:Article, refereed
Article Subtype:Research Article
Publisher:World Scientific Publishing
Note:Publication type according to Uni Basel Research Database: Journal article -- The final publication is available at World Scientific Publishing, see DOI link
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Last Modified:08 Feb 2020 14:47
Deposited On:26 Jan 2018 15:23

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