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A lattice Boltzmann code for complex fluids

Build Status CII Best Practices

Ludwig is a parallel code for the simulation of complex fluids, which include mixtures, colloidal suspensions, gels, and liquid crystals. It takes its name from Ludwig Boltzmann, as it uses a lattice Boltzmann method as a basis for numerical solution of the Navier Stokes equations for hydrodynamics. It typically combines hydrodynamics with a coarse-grained order parameter (or order parameters) to represent the "complex" part in a free energy picture.

The code is written in standard ANSI C, and uses the Message Passing Interface for distributed memory parallelism. Threaded parallelism is also available via a lightweight abstraction layer ("Target Data Parallel" or "TargetDP") which currently supports either OpenMP or CUDA (NVIDIA GPUs) from a single source.


Copy a config file from the config directory to the top level directory and make any changes required. E.g.,

$ cp config/
$ make serial
$ make
$ make test

Note that the tests expect standard C assertions to be active; for production runs, one should add the standard preprocessor option -DNDEBUG to the compiler options in the file.

If a parallel build is wanted omit the serial step, for example,

$ cp config/
$ make
$ make test

Full details of the build process are available at

Background and Tutorial

Background documentation on the LB model and various free energy choices is available in the docs directory.

$ cd docs
$ make

will produce a pdf version of the LaTeX source.

A short tutorial, which includes some examples in which the results are visualised, is also provided:

$ cd docs/tutorial
$ make

to produce a pdf of the tutorial instructions.


If you would like to contribute, please consider a pull request. See for further details of testing and development.



Recent release versions have a Zenodo-provided DOI. Please consider using the appropriate DOI as a reference if you use Ludwig in your publications.


For bug reports, problems, and other issues, please open a new issue.