Ludwig-FR

A lattice Boltzmann code for complex fluids. This is a fork of the popular Ludwig LB code for complex fluids with additions made for the simulation of complex disclination structures in liquid crystals.

Major Changes

* added wall anchoring "patterned" for 2d defects patterned on walls

Todo

• Anchoring surface patterning for 2D LC defects
• Asymmetric walls
• Cmake?

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.

Installation

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 are available at https://ludwig.epcc.ed.ac.uk/.

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.

Contributing

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

Attribution

Please cite the original U. Edinburgh Soft Matter Group repository for Ludwig that this code is forked from.

Help

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