HydroGym: A Reinforcement Learning Platform for Flow Control

License: MIT (code) / Nature paper · Updated 2026-09-18

HydroGym provides a Gymnasium-compatible interface for training reinforcement learning agents on CFD problems, developed by a collaboration spanning the University of Washington, RWTH Aachen, TU Munich and others, and published in Nature.

What it offers: Dozens of pre-configured flow environments (cylinder, fluidic pinball, open cavity, NACA 0012 airfoil, turbulent channel, Kolmogorov flow, turbulent boundary layer) backed by finite-element (Firedrake), lattice-Boltzmann and finite-volume (MAIA), spectral-element (NEK5000) and fully differentiable (JAX) solvers. It runs from a laptop to exascale HPC and works with Stable-Baselines3 or RLlib.

Reported results: A policy trained on a turbulent channel flow at a friction Reynolds number of about 206 was deployed zero-shot onto 3D NACA 0012 wing sections, reducing surface skin friction by roughly 38% and overall drag by about 11%, at an estimated four orders of magnitude lower core-hour cost than training directly on the wing.

Industrial relevance: Turbulent drag accounts for a large share of energy loss in transport and pipeline flow. HydroGym turns flow control from bespoke one-off studies into a benchmarked, reproducible workflow.

Tags: Flow ControlReinforcement LearningDrag ReductionTurbulenceOpen Platform
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