The Multiphase Code Repository by HZDR provides research code based on OpenFOAM Foundation Software for simulating multiphase flows. Its focus is MultiMorph, an morphology-adaptive Euler-Euler model, supported by validation cases and workflows for robust industrial applications.
The Multiphase Code Repository by HZDR provides research-focused source code for the numerical simulation of multiphase flows, mainly using the Euler-Euler model, also known as two-fluid model or multi-field approach. Developments are focused on the Morphology-Adaptive Multifield Euler-Euler Model (MultiMorph), which combines resolved and unresolved morphologies in a single simulation framework. In addition, a variety of closure models for predictive Eulerian multiphase flow simulations are provided. The repository is based on the OpenFOAM Foundation development line and is continuously updated to include recent changes.
We maintain an active partnership with the core developers from the OpenFOAM Foundation and CFD Direct, who provide frequent, high-quality improvements to the upstream code base and maintain long-term technical excellence. By design, this is a research repository intended to support rapid prototyping of methods in a collaborative environment. However, a strong focus is placed on the sustainability and long-term availability of developments, so they can be pushed upstream when there is a demonstrated demand and sufficient technical maturity. In order to avoid version lock-in, code and case setups are kept aligned with upstream changes and a wide range of test and application cases is provided for continuous verification and validation.
The long-term goal is to deliver generally applicable, robust and efficient Eulerian multiphase simulation methods for industrial scale applications and to develop a reliable and comprehensive validation database. Industry transfer is fostered by providing portable simulation workflows and a collaboration-friendly infrastructure.
This repository is complemented by two additional projects: the Multiphase Case Repository by HZDR, which provides an extensive and regularly used validation database, and the Multiphase Python Repository by HZDR, which offers tools for reproducible multiphase Computational Fluid Dynamics (CFD) workflows.
The Morphology-Adaptive Multifield Euler-Euler Model (MultiMorph) is a separated morphology-adaptive Eulerian method in which each morphology is represented by its own numerical phase, i.e., without blending between morphologies. Interfacial closures are selected according to local morphology, and the coupling strategy adapts to local mesh resolution: for resolved morphologies, Volume-of-Fluid-like treatment is achieved via tight interfacial momentum exchange coupling, unresolved morphologies follow a Euler-Euler strategy, and partially resolved states are handled adaptively. This enables resolution-dependent morphology transfers in both directions and relaxes strict resolution requirements while preserving physical consistency.
MultiMorph has already been used in canonical validation cases (e.g., rising bubbles, stratified flows, and plunging jets) as well as in more complex engineering applications such as swirl separators, droplet separators, distillation column tray, hydroprocessors, and air-lubrication scenarios. Application and demonstration cases can be found in the Multiphase Case Repository by HZDR.
For more information on the theory and background of morphology-adaptive Eulerian methods refer to Krull et al. (2026), Krull et al. (2024), Meller et al. (2024), Meller et al. (2023), Meller et al. (2021), Schlegel et al. (2026), Schlegel et al. (2023), and Tekavcic et al. (2021).
When using the Multiphase Code Repository by HZDR for OpenFOAM Foundation Software cite as
Schlegel et al. (2026). Multiphase Code Repository by HZDR for OpenFOAM
Foundation Software. Rodare. <https://doi.org/10.14278/rodare.767>.
OpenFOAM(R) is a registered trade mark of OpenCFD Limited, producer and distributor of the OpenFOAM(R) software via www.openfoam.com. The Multiphase Code Repository by HZDR for OpenFOAM Foundation Software is not compatible with the software released by OpenCFD Limited, but is developed for the software released by the OpenFOAM Foundation via www.openfoam.org.
This repository contains simulation setups for Multiphase Code Repository by HZDR. The simulation setups are divided into mono- and polydisperse bubbly flows utilizing the set of Baseline models of HZDR, setups using the morphology-adaptive multifield two-fluid model and miscellaneous cases.
Toolkit for reproducible multiphase CFD workflows.