ReMKiT1D

Overview

ReMKiT1D is a flexible framework for building 1D fluid models with built-in support for coupled electron kinetics. It allows for the rapid construction of simplified models, particularly in the context of Scrape-Off Layer physics, and comes with a Python support module offering Domain-Specific Language features.

The code numerically solves custom systems of ODEs, 1D PDEs arising in fluid modelling, as well as the Vlasov-Fokker-Planck-Boltzmann equation for electrons. These can be specified through a Python interface that acts as a Domain-Specific Language (DSL) and provides data analysis and visualisation using tools such as xarray and holoviews. 

The framework is designed for both model developers and modellers.

Key benefits

Benefits of using ReMKiT1D include:

• capable of handling both reactive fluid equations and electron kinetics 
• flexible and extensible  
• designed to be user-friendly with Python interface 
• domain-specific language features  
• performant Fortran back-end capable of running well on HPC machines 

ReMKiT1D details

Technical specification

The framework consists of two components: 

• the Fortran backend, which ingests a config.json file specifying the simulation setup and produces hdf5 output files  
• the Python interface, which abstracts the construction of the config.json file and provides analysis and visualisation utilities 

Programming language

Fortran, Python

Compatible platforms / systems

Linux (recommended), Windows (via WSL), macOS

Dependencies

For the Fortran backend:

• MPI – tested with mpich-3.4.1
• HDF5
• pFUnit – only if unit testing required
• PETSc – tested with versions 3.16 and 3.17 (3.18 not compatible) – requires hypre
• json-fortran – currently using version 8.2.5
• sundials (as of v.1.2.0)

For the Python library:

• numpy
• xarray
• holoviews
• panel
• matplotlib
• h5py
• scipy
• pylatex

System requirements

• For the Python configuration interface – recent basic laptop
• For running fluid simulation – workstation class laptop not older than 5 years
• For running kinetic simulations (in production) – access to HPC facilities

Key features

The key features of ReMKiT1D are:

• support for solving 1D fluid and electron kinetic equations with a fully implicit method
• built-in support for defining custom equations and terms using DSL features
• built-in support for dealing with reactive/collisional-radiative models
• visualisation and analysis support through built-in dashboard

Use cases

Use cases for ReMKiT1D include:

• fluid and kinetic modelling of ELM burn-through
• exploration of reduced models through rapid model iteration
• calibration of kinetic effects for higher dimensionality codes

Licence information

ReMKiT1D is available under the GPL-3.0 open source licence.

Support

Documentation

• Get the Python interface and general documentation on GitHub.
• Get the Fortran backend documentation on GitHub.

Community support

Go to the ReMKiT1D GitHub issues for:

Fortran

Python

Technical support

For support using ReMKiT1D, contact us.

Collaboration opportunities

We welcome collaborations to:

• use ReMKiT1D models or construct your own for fusion research
• contribute to development of framework features

Code paper

Read the code paper for ReMKiT1D on ScienceDirect:

ReMKiT1D – A framework for building reactive multi-fluid models of the tokamak scrape-off layer with coupled electron kinetics in 1D

Development status

Active

Version information

• Fortran: v1.3.0 (Aug 29^th 2025)
• Python: v2.0.0 (Aug 29^th 2025)

Contributors

• Stefan Mijin
• Sid Leigh