Project and Generate: Divergence-Free Neural Operators for Incompressible Flows

Fuente: arXiv
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Autores principales: Li, Xigui, Zhang, Hongwei, Jiang, Ruoxi, Chen, Deshu, Lin, Chensen, Han, Limei, Qi, Yuan, Guo, Xin, Cheng, Yuan
Formato: Preprint
Publicado: 2026
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author Li, Xigui
Zhang, Hongwei
Jiang, Ruoxi
Chen, Deshu
Lin, Chensen
Han, Limei
Qi, Yuan
Guo, Xin
Cheng, Yuan
author_facet Li, Xigui
Zhang, Hongwei
Jiang, Ruoxi
Chen, Deshu
Lin, Chensen
Han, Limei
Qi, Yuan
Guo, Xin
Cheng, Yuan
contents Learning-based models for fluid dynamics often operate in unconstrained function spaces, leading to physically inadmissible, unstable simulations. While penalty-based methods offer soft regularization, they provide no structural guarantees, resulting in spurious divergence and long-term collapse. In this work, we introduce a unified framework that enforces the incompressible continuity equation as a hard, intrinsic constraint for both deterministic and generative modeling. First, to project deterministic models onto the divergence-free subspace, we integrate a differentiable spectral Leray projection grounded in the Helmholtz-Hodge decomposition, which restricts the regression hypothesis space to physically admissible velocity fields. Second, to generate physically consistent distributions, we show that simply projecting model outputs is insufficient when the prior is incompatible. To address this, we construct a divergence-free Gaussian reference measure via a curl-based pushforward, ensuring the entire probability flow remains subspace-consistent by construction. Experiments on 2D Navier-Stokes equations demonstrate exact incompressibility up to discretization error and substantially improved stability and physical consistency.
format Preprint
id arxiv_https___arxiv_org_abs_2603_24500
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Project and Generate: Divergence-Free Neural Operators for Incompressible Flows
Li, Xigui
Zhang, Hongwei
Jiang, Ruoxi
Chen, Deshu
Lin, Chensen
Han, Limei
Qi, Yuan
Guo, Xin
Cheng, Yuan
Machine Learning
Fluid Dynamics
Learning-based models for fluid dynamics often operate in unconstrained function spaces, leading to physically inadmissible, unstable simulations. While penalty-based methods offer soft regularization, they provide no structural guarantees, resulting in spurious divergence and long-term collapse. In this work, we introduce a unified framework that enforces the incompressible continuity equation as a hard, intrinsic constraint for both deterministic and generative modeling. First, to project deterministic models onto the divergence-free subspace, we integrate a differentiable spectral Leray projection grounded in the Helmholtz-Hodge decomposition, which restricts the regression hypothesis space to physically admissible velocity fields. Second, to generate physically consistent distributions, we show that simply projecting model outputs is insufficient when the prior is incompatible. To address this, we construct a divergence-free Gaussian reference measure via a curl-based pushforward, ensuring the entire probability flow remains subspace-consistent by construction. Experiments on 2D Navier-Stokes equations demonstrate exact incompressibility up to discretization error and substantially improved stability and physical consistency.
title Project and Generate: Divergence-Free Neural Operators for Incompressible Flows
topic Machine Learning
Fluid Dynamics
url https://arxiv.org/abs/2603.24500