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Upcoming Colloquia & Seminars

  1. Model problems in fluid dynamics: Profile decompositions method: a common thread of many works arising from geometry, physics and fluid mechanics

    Location: MSRI: Online/Virtual
    Speakers: Hajer Bahouri (Laboratoire Jacques-Louis Lions; Centre National de la Recherche Scientifique (CNRS))

    To participate in this seminar, please register here: https://www.msri.org/seminars/25657

    Abstract:

    In this talk, we survey the main ideas of profile decompositions techniques. Then we showcase their wide range of applications from the geometric and PDE viewpoints, emphasising their contributions in fluid mechanics.

    Updated on May 12, 2021 12:08 PM PDT
  2. Water waves and other interface problems (Part 1): Entropies of free surface flows in fluid dynamics

    Location: MSRI: Online/Virtual
    Speakers: Thomas Alazard (Ecole Normale Supérieure Paris-Saclay; Centre National de la Recherche Scientifique (CNRS))

    To participate in this seminar, please register here: https://www.msri.org/seminars/25657

    Abstract: 

    I will discuss recent works with Didier Bresch, Nicolas Meunier and Didier Smets about the dynamics of a free surface transported by an incompressible flow obeying Darcy’s law. I will consider the Hele-Shaw and Mullins-Sekerka equations, as well as the thin-film and Boussinesq equations. For these equations, I will present monotonicity properties of different natures : maximum principles, Lyapunov functionals and entropies. The analysis is based on exact identities which in turn allow to study the Cauchy problem for classical solutions in any subcritical Sobolev spaces. 

    Updated on May 14, 2021 07:21 AM PDT
  3. Water waves and other interface problems (Part 2): Flexural-gravity waves generated by moving loads on ice plates

    Location: MSRI: Online/Virtual
    Speakers: Emilian Parau (University of East Anglia)

    To participate in this seminar, please register here: https://www.msri.org/seminars/25657

     

    Three-dimensional waves generated by moving loads on top of floating ice plates are investigated. The ice plates are modelled using the thin plate theory. Different viscoelastic models for the ice will be presented and wave patterns will be calculated. Nonlinear steady waves will be computed using boundary integral methods. Fully dispersive weakly nonlinear equations will also be derived and comparisons of solutions with field observations will be provided. Other related flows will be discussed.

    Updated on May 14, 2021 07:22 AM PDT
  4. Graduate Student Working Group: Ocean boundary layer formation: the quasi-geostrophic model & TBA

    Location: MSRI: Online/Virtual
    Speakers: Mostafa Hassan (Johns Hopkins University), Gabriela Lopez-Ruiz (Sorbonne University)

    To participate in this seminar, please register here: https://www.msri.org/seminars/25657

    1st Speaker: Gabriela López Ruiz (Sorbonne Université)
    Title: Ocean boundary layer formation: the quasi-geostrophic model
    Abstract: We will talk about the impact of small-scale irregularities on the coasts on oceanic circulation at the mesoscale. We study a singular perturbation problem from meteorology known as the quasi-geostrophic model. A complete asymptotic analysis is performed assuming rough coasts do not present a particular structure. In particular, we establish the well-posedness of the boundary layer system and the asymptotic behavior of the solution far from the boundary. We investigate the action of pseudodifferential operators in nonlocalized Sobolev spaces and use ergodic properties to deal with the singular behavior of the eastern boundary layer profiles. These results generalize the ones of Bresch and Gérard-Varet (Commun. Math. Phys. 253, 81–119 (2005)) for periodic roughness.

    2nd Speaker : Mostafa Hassan (University of Wisconsin Madison)
    Title: TBA

    Abstract: The goal of our work is to prove global well-posedness for quasilinear wave equations with as few  assumptions on the initial data as possible. Current partial results, including almost-global well-posedness and  globalwell-posedness with sub-optimal but reduced regularity assumptions will be presented, as well as the general idea we believe can yield a more optimal result. The proofs utilize the ghost weight method, localization  in time and space adapted to the light cone geometry, and careful Sobolev-type embeddings that require as few vector fields as possible.

    Updated on May 14, 2021 07:14 AM PDT
  5. Euler/Navier Stokes (Part 1): Recent results on the instability of boundary layer models

    Location: MSRI: Online/Virtual
    Speakers: David Gerard-Varet (Université de Paris XI)

    To participate in this seminar, please register here: https://www.msri.org/seminars/25657

    Many hydrodynamic instabilities take place near a solid boundary at high Reynolds number. This reflects into the mathematical theory of the classical Prandtl model for the boundary layer: it exhibits high frequency instabilities, limiting its well-posedness to infinite regularity (Gevrey) spaces. After reviewing shortly this fact, we will turn to the Triple Deck model, an improvement of the Prandtl system that is commonly accepted to be more stable. We will show that this is actually wrong, and that the recent result of analytic well-posedness by Iyer and Vicol is more or less optimal.

    This is based on joint work with Helge Dietert.

    Updated on May 11, 2021 04:49 PM PDT
  6. Euler/Navier Stokes (Part 2): Incompressible Euler limit from the Boltzmann equation with diffuse boundary

    Location: MSRI: Online/Virtual
    Speakers: Juhi Jang (University of Southern California)

    To participate in this seminar, please register here: https://www.msri.org/seminars/25657

    Abstract:

    In this talk, we discuss the derivation of the incompressible Euler equations with the no-penetration boundary condition from the Boltzmann equation with the diffuse reflection boundary condition. The main difficulty lies in the boundary mismatch in the limit, as the no-penetration boundary condition of Euler flows does not honor the diffuse reflection boundary condition at the leading order. To overcome this, we study the Euler limit through the Navier Stokes flows of large Reynolds numbers satisfying the no-slip boundary condition as intermediary approximations via a new Hilbert type expansion. The talk is based on a joint work with Chanwoo Kim. 

     

     

    Updated on May 14, 2021 06:53 AM PDT
  7. Fellowship of the Ring, National Seminar:

    Location: MSRI: Online/Virtual

    To attend this seminar, you must register in advance, by clicking HERE.

    Updated on Jan 11, 2021 04:37 PM PST
  8. Applied fluids: Modelling Compressible Two-Phase Flow across Scales using Sharp and Diffuse Interface Ideas

    Location: MSRI: Online/Virtual
    Speakers: Christian Rohde (Universität Stuttgart)

    To participate in this seminar, please register here: https://www.msri.org/seminars/25657

    Abstract: In the lecture we will consider the multi-scale modeling and  numerics for compressible two-phase flow. A sharp-interface approach appears to be adequate on a continuum scale where phase boundaries are fully resolved. This results in a concept using the compressible Euler equations in the bulk domains and understanding the phase boundary as a  discontinuous (shock) wave. We propose a numerical algorithm that relies on new exact solutions of special Riemann problems accounting for molecular-scale information to determine the phase dynamics.  
    Two-phase flow with topological changes can hardly be accessed by the  sharp-interface ansatz. In the second part of the lecture we will therefore present a class of diffuse-interface models that build on the  classical compressible Navier-Stokes-Korteweg model. We will show that these models can provide the basis for reliable computations of  convection-dominated  processes (e.g. droplet collision). Moreover, this diffuse-interface ansatz is compatible with homogenization techniques. Therefore we will conclude the lecture with a discussion of up-scaling compressible two-phase flow in porous media.

    Updated on May 10, 2021 02:48 PM PDT
  9. Fluid Dynamics Farewell Tea

    Location: MSRI: Online/Virtual
    Updated on Apr 22, 2021 10:28 AM PDT
  1. 2021 African Diaspora Joint Mathematics Workshop

    The African Diaspora Joint Mathematics Workshop (ADJOINT) will take place at the Mathematical Sciences Research Institute in Berkeley, CA from June 21 to July 2, 2021.

    ADJOINT is a two-week summer activity designed for researchers with a Ph.D. degree in the mathematical sciences who are interested in conducting research in a collegial environment.  

    The main objective of ADJOINT is to provide opportunities for in-person research collaboration to U.S. mathematicians, especially those from the African Diaspora, who will work in small groups with research leaders on various research projects. 

    Through this effort, MSRI aims to establish and promote research communities that will foster and strengthen research productivity and career development among its participants. The ADJOINT workshops are designed to catalyze research collaborations, provide support for conferences to increase the visibility of the researchers, and to develop a sense of community among the mathematicians who attend. 

    The end goal of this program is to enhance the mathematical sciences and its community by positively affecting the research and careers of African-American mathematicians and supporting their efforts to achieve full access and engagement in the broader research community. 

    Each summer, three to five research leaders will each propose a research topic to be studied during a two-week workshop.

    During the workshop, each participant will: 

    • conduct research at MSRI within a group of four to five mathematicians under the direction of one of the research leaders 
    • participate in professional enhancement activities provided by the onsite ADJOINT Director 
    • receive funding for two weeks of lodging, meals and incidentals, and one round-trip travel to Berkeley, CA 

    After the two-week workshop, each participant will:

    • have the opportunity to further their research project with the team members including the research leader 
    • have access to funding to attend conference(s) or to meet with other team members to pursue the research project, or to present results 
    • become part of a network of research and career mentors

    Updated on Mar 11, 2021 01:48 PM PST