arXiv Machine Learning

A Variational Optimal Transport Operator on Incompressible Flow

The paper introduces the Variational Incompressible Optimal Transport (VIOT) operator, a generative neural operator that predicts divergence‑free velocity fields for incompressible density transport. VIOT combines a stream‑function representation, a regularized transport objective, and a Fourier Neural Operator backbone to amortize the solve across new source‑target pairs and grid resolutions. Experiments on 2D and 3D benchmarks show that VIOT produces full transport trajectories in seconds, achieving roughly a $10^4 imes$ speedup over per‑instance baselines that require hours of optimization.

arXiv Machine Learning
Aug 28

COFM: Consistent Optimal Transport Flow Matching via Partially Input Convex Neural Networks

The paper introduces COFM, a framework for consistent optimal transport flow matching that uses partially input convex neural networks (PICNN) to parameterize the transport potential. By adding a Hamilton‑Jacobi residual to the training objective, COFM enforces dynamical consistency and supports both one‑step transport and multi‑step ODE sampling without costly inner optimization. Experiments on benchmark datasets show that COFM achieves competitive performance while reducing L^2‑UVP by over 2× and cutting computational time by about 9× compared to state‑of‑the‑art models.

By Fanghui Song, Zhongjian Wang, Jiebao Sun
arXiv Machine Learning
4d ago

Coarse-Graining Optimal Transport for Rollout-Free Post-Training of Flow Matching

The paper introduces ReCouple, a framework that constructs coarse-grained optimal transport (OT) couplings to improve flow matching without requiring rollouts. Extensions ReCouple+ and ReCouple++ address continuous-source settings and add spatial regularization, respectively. Experiments show that these methods balance coupling optimality, neural network realizability, and generation quality, especially in low NFE regimes.

By Soon Hoe Lim, Aditi Gupta, Michael W. Mahoney, N. Benjamin Erichson
arXiv AI
Sep 2

Training-Free Refinement of Flow Matching with Divergence-based Sampling

The paper introduces Flow Divergence Sampler (FDS), a training‑free method that refines intermediate states in flow‑matching models by using the divergence of the marginal velocity field to detect and correct misguidance toward low‑density regions. FDS operates during inference, requires no additional training, and can be applied as a plug‑and‑play module with standard solvers and existing flow backbones. Experiments show that FDS consistently improves fidelity in tasks such as text‑to‑image synthesis and inverse problems.

By Yeonwoo Cha, Jaehoon Yoo, Semin Kim, Yunseo Park, Jinhyeon Kwon, Seunghoon Hong
arXiv Machine Learning
Oct 22

Density-Level Backward Error for Low-NFE Generative Flows

The paper introduces a density‑level backward‑error framework for low‑NFE generative ODE sampling, identifying the part of a solver’s modified‑equation defect that alters the evolving marginal while ignoring solenoidal trajectory distortion. This leads to a solver‑order‑aware compute‑allocation rule and an objective for choosing numerically favorable velocity representatives, distinct from schedule search or higher‑order solver design. Experiments on Gaussian, mixture models, and a pretrained CIFAR‑10 EDM probability‑flow ODE show that density‑aware allocation consistently improves fixed‑update Euler sampling in the low‑NFE regime and accelerates convergence to a dense Euler reference.

By Ewsey Obzherin, Valentin Khrulkov
arXiv Machine Learning
Sep 2

Efficient Adaptation of ROMs for Unsteady Flows Using Data Assimilation

The paper presents a lightweight retraining strategy for a parameterized Reduced Order Model (ROM) that achieves full‑model accuracy using only a fraction of the computational effort and sparse observations. The ROM architecture combines a Variational Autoencoder for dimensionality reduction with a transformer network that evolves latent states while accounting for the Reynolds number as an external control variable. By leveraging the probabilistic VAE, the method generates trajectory ensembles and uncertainty estimates, and adapts to out‑of‑sample parameters through sparse data assimilation with an ensemble Kalman filter, focusing retraining on the autoencoder to correct latent manifold distortions.

By Isma\"el Zighed, Andrea N\'ovoa, Luca Magri, Taraneh Sayadi
Hugging Face Trending Papers
Jul 13

Self-Consistent Flow: Unifying Velocity and Endpoint Prediction for Rectified Flow Models

In rectified-flow-based generative models, the neural network can be trained to predict two different targets, such as the instantaneous velocity or the data endpoint, to perform denoising. Although prior work shows that these parameterizations lead to different empirical behaviors, the mechanisms underlying their respective advantages remain to be underexplored, and how to combine them effectively is still unclear.