Self-similar singularity profiles for CCF

Which self-similar blow-up profiles exist for the Córdoba–Córdoba–Fontelos equation, and how many unstable modes do they have? A stable profile and the first unstable profile were known before searches for further branches.

Why it matters and what counts as progress

Why it matters: Additional unstable CCF profiles extend the blow-up landscape beyond the stable branch and first unstable solution.

What counts as progress: Find a new unstable branch with controlled numerical residuals and modes, or prove existence and instability of a computed profile.

How the problem developed

  1. 2023 · Numerical candidate [1]

    Jiajie Wang, Ke Chen, Thomas Y. Hou and Zhen Lei Reported numerical discovery of the first unstable self-similar profile for the Córdoba–Córdoba–Fontelos equation, alongside stable profiles for related fluid models.

  2. 17 Sept 2025 · Numerical candidates [2]

    Jiajie Wang and collaborators Reported a second unstable CCF profile and multiple stable or unstable profiles for IPM and 2D Boussinesq equations, with dense-grid residual and linearized-mode tests.

AI contribution

Discovery of Unstable Singularities

Yongji Wang, Mehdi Bennani, James Martens, Sébastien Racanière, Sam Blackwell, Alex Matthews, Stanislav Nikolov, Gonzalo Cao-Labora, Daniel S. Park, Martin Arjovsky, Daniel Worrall, Chongli Qin, Ferran Alet, Borislav Kozlovskii, Nenad Tomašev, Alex Davies, Pushmeet Kohli, Tristan Buckmaster, Bogdan Georgiev, Javier Gómez-Serrano, Ray Jiang, Ching-Yao Lai

Wang and collaborators report a second unstable self-similar Córdoba–Córdoba–Fontelos (CCF) profile, stable and three unstable incompressible porous media (IPM) profiles, and stable and three unstable 2D Boussinesq profiles. They test residuals and linearized modes on dense grids. A fourth Boussinesq profile remains an unvalidated candidate.

AI involvementAI-centered
ImportanceNotable
Technical verificationPartial
Human understandingFull
Paper date:

Sources

  1. Wang, Lai, Gómez-Serrano and Buckmaster, On the stability of singularity formation for the Córdoba–Córdoba–Fontelos equation
  2. Wang et al., Neural networks find numerical candidates for unstable fluid singularities
  3. Wang and collaborators’ unstable-singularity study
  4. Follow-up numerical refinements
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