A lattice Boltzmann code for complex fluids
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 OpenMP, CUDA (NVIDIA GPUs) or HIP (AMD 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/unix-gcc-default.mk config.mk
$ 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 config.mk file.
If a parallel build is wanted omit the serial step, for example,
$ cp config/unix-mpicc-default.mk config.mk
$ make
$ make test
Full details of the build process, and tutorials on how to use the code are available at https://ludwig.epcc.ed.ac.uk/.
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.
If you would like to contribute, please consider a pull request.
See CONTRIBUTING.md 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.
From Version 0.19.0 we have included a copy of cJSON which is released
under an MIT license by Gave Gamble at https://github.com/DaveGamble/cJSON.
For bug reports, problems, and other issues, please open a new issue.