The OpenFOAM Foundation is pleased to announce the release of version 9 of the OpenFOAM open source CFD toolbox. Version 9 is a snapshot of the OpenFOAM development version which, through sustainable development, is always-releasable. It provides new functionality and major improvements to existing code, with strict demands on usability, robustness and extensibility. OpenFOAM 9 includes the following key developments:

• Multiphase: improved the performance, numerics and robustness of multiphase solvers.
• Transport: significant redesign of thermophysical transport models.
• Thermophysical: automatic compilation of model packages, mixing rules, tabulated input.
• Heat transfer: made calculations consistent between solvers, BCs and post-processing.
• Particle tracking: cloud types selected by user, not hard-coded into solvers.
• Reactions: improved robustness of numerics and chemistry and added general controls.
• Mesh: refactored parts of snappyHexMesh, decomposition and manipulation tools.
• Surface Film: introduced standard thermophysical modelling.
• Function Objects: overhaul of packaged function objects for improved usability.
• Models and Constraints: fvOptions replaced by more flexible fvModels and fvConstraints.
• Case Configuration: enhanced scripts and added new Function2 functions of 2 variables.
• Computation: improved robustness and performance of I/O, compilation, numerics.