An Analytical and AI-discovered Stable, Accurate, and Generalizable Subgrid-scale Closure for Geophysical Turbulence

• URL: http://arxiv.org/abs/2509.20365v2
• Date: Wed, 01 Oct 2025 00:32:31 GMT
• Title: An Analytical and AI-discovered Stable, Accurate, and Generalizable Subgrid-scale Closure for Geophysical Turbulence
• Abstract summary: Large-eddy simulation (LES) with this closure is accurate and stable, reproducing DNS statistics including those of extremes.<n>We also show that the new closure could be derived from a 4th-order truncated Taylor expansion.
• Score: 0.0
• License: http://creativecommons.org/licenses/by/4.0/
• Abstract: By combining AI and fluid physics, we discover a closed-form closure for 2D turbulence from small direct numerical simulation (DNS) data. Large-eddy simulation (LES) with this closure is accurate and stable, reproducing DNS statistics including those of extremes. We also show that the new closure could be derived from a 4th-order truncated Taylor expansion. Prior analytical and AI-based work only found the 2nd-order expansion, which led to unstable LES. The additional terms emerge only when inter-scale energy transfer is considered alongside standard reconstruction criterion in the sparse-equation discovery.

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