Flow of elastic networks
Final Report Abstract
Networks and flow of networks arise naturally in the study of multiphase systems and of the dynamics of their interfaces. Here, the word network refers to a set of curves “glued” together at their end-points. Each junction point is free to move in a more favorable energy configuration with the condition that the topology of the system has to be conserved. One of the main contributions of this project is the understanding of the evolution of networks that are driven by energy steepest descent and that describe elastic objects. The energy leading the evolution is the elastic energy which is quadratic in the curvature of the curves. As a consequence, the resulting system of evolution equations is quasi-linear and of higher order. The novelty of the project lies in the combination of the study of networks with fourth order geometric partial differential equations. The main challenges are the higher order nature of the equations, the modelling and control of the junction points as well as the geometric nature of the problem. Thanks to a good understanding of the geometry involved and capturing many information from this, we establish a well-posedness result for the problem and discover sufficient conditions for the existence of a global solution for a large class of initial data. Our further investigations are motivated either by the study of networks, or by the study of variational problems (such as obstacle problems, problems in an anisotropic ambient space, etc.) and their associated evolution problems involving the elastic energy or some generalization thereof. Besides some numerical features, in the project we consider mainly analytical aspects with two main objectives. The first is the study of the asymptotic behavior of solutions and in establishing new techniques to reach this goal (like the Løjasiewicz-Simon inequality for constrained problem or a detailed study of the possible critical points). The second is the study of qualitative properties of solutions like regularity, preservation of convexity or embeddedness. Due to the higher order nature of the problems, such questions lead to interesting new theories and results.
Publications
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An obstacle problem for elastic curves: Existence results. Interfaces and Free Boundaries, Mathematical Analysis, Computation and Applications, 21(1), 87-129.
Müller, Marius
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Elastic flow of networks: long-time existence result. Geometric Flows, 4(1), 83-136.
Dall’Acqua, Anna; Lin, Chun-Chi & Pozzi, Paola
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A Second Order Gradient Flow of p-Elastic Planar Networks. SIAM Journal on Mathematical Analysis, 52(1), 682-708.
Novaga, Matteo & Pozzi, Paola
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Elastic flow of networks: short-time existence result. Journal of Evolution Equations, 21(2), 1299-1344.
Dall’Acqua, Anna; Lin, Chun-Chi & Pozzi, Paola
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On gradient flows with obstacles and Euler’s elastica. Nonlinear Analysis, 192, 111676.
Müller, Marius
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On the Convergence of the Elastic Flow in the Hyperbolic Plane. Geometric Flows, 5(1), 40-77.
Müller, Marius & Spener, Adrian
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On the Łojasiewicz–Simon gradient inequality on submanifolds. Journal of Functional Analysis, 279(8), 108708.
Rupp, Fabian
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Stability analysis for the anisotropic curve shortening flow of planar networks
Gößwein, M., Novaga, M. & Pozzi, P.
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Uniqueness for a Second Order Gradient Flow of Elastic Networks. Lecture Notes in Computational Science and Engineering, 785-792. Springer International Publishing.
Novaga, Matteo & Pozzi, Paola
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A Li–Yau inequality for the 1-dimensional Willmore energy. Advances in Calculus of Variations, 16(2), 337-362.
Müller, Marius & Rupp, Fabian
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Anisotropic Curvature Flow of Immersed Networks. Milan Journal of Mathematics, 89(1), 147-186.
Kröner, Heiko; Novaga, Matteo & Pozzi, Paola
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On motion by curvature of a network with a triple junction. The SMAI Journal of computational mathematics, 7, 27-55.
Pozzi, Paola & Stinner, Björn
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The Willmore flow with prescribed isoperimetric ratio
Rupp, F.
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The biharmonic Alt–Caffarelli problem in 2D. Annali di Matematica Pura ed Applicata (1923 -), 201(4), 1753-1799.
Müller, Marius
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Convergence of a scheme for an elastic flow with tangential mesh movement. ESAIM: Mathematical Modelling and Numerical Analysis, 57(2), 445-466.
Pozzi, Paola & Stinner, Björn
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Elastic graphs with clamped boundary and length constraints. Annali Di Matematica Pura Ed Applicata (1923 -), 203(3), 1137–1158.
Dall’Acqua, Anna & Deckelnick, Klaus
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On an elastic flow for parametrized curves in R n suitable for numerical purposes. Annali di Matematica Pura ed Applicata (1923 -), 202(5), 2541-2560.
Pozzi, Paola
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The volume-preserving Willmore flow. Nonlinear Analysis, 230, 113220.
Rupp, Fabian
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A dynamic approach to heterogeneous elastic wires. Journal of Differential Equations, 392, 1-42.
Dall'Acqua, Anna; Langer, Leonie & Rupp, Fabian
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An obstacle problem for the p-elastic energy. Calculus of Variations and Partial Differential Equations, 63(6).
Dall’Acqua, Anna; Müller, Marius; Okabe, Shinya & Yoshizawa, Kensuke
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Conservation, Convergence, and Computation for Evolving Heterogeneous Elastic Wires. SIAM Journal on Mathematical Analysis, 56(4), 4494-4529.
Dall’Acqua, Anna; Jankowiak, Gaspard; Langer, Leonie & Rupp, Fabian
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Existence and convergence of the length-preserving elastic flow of clamped curves. Journal of Evolution Equations, 24(3).
Rupp, Fabian & Spener, Adrian
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On the convergence of the Willmore flow with Dirichlet boundary conditions. Nonlinear Analysis, 241, 113475.
Schlierf, Manuel
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The Willmore flow of tori of revolution. Analysis & PDE, 17(9), 3079-3124.
Dall’Acqua, Anna; Müller, Marius; Schätzle, Reiner & Spener, Adrian
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Optimal thresholds for preserving embeddedness of elastic flows. American Journal of Mathematics, 147(1), 33-80.
Miura, Tatsuya; Müller, Marius & Rupp, Fabian
