Get and Build waLBerla

This page describes how to obtain a copy of waLBerla and how to setup your environment for development.

# Getting waLBerla

## Clone the repository

As a first step, check out the waLBerla source code from our git repository:

  git clone https://i10git.cs.fau.de/walberla/walberla


If you are not familiar with the git version control system, this page is a good starting point.

# Building waLBerla

## Libraries and CMake Options

To compile waLBerla with all modules and features a few third-party libraries are required.

### Boost

The boost library is the only required third-party library. It is installed on most Linux system by default and should be detected by cmake. If boost resides at a non-standard location, you have to set the environment variable BOOST_ROOT in order to have it detected by cmake.

### MPI (optional)

The message passing interface (MPI) library is required if you want to run waLBerla with distributed memory parallelization. If MPI is not installed on your system, you still can compile a serial or even an OpenMP thread-parallel version of waLBerla. You can disable MPI using the CMake switch WALBERLA_BUILD_WITH_MPI.

### Qt (optional)

waLBerla can be build with a graphical user interface, which is disabled by default. The GUI is mainly useful for debugging and visualizing very small scale simulations. To enable the GUI, set the CMake switch WALBERLA_ENABLE_GUI to ON and install Qt4 on your system.

## Compiling the code

  # create a separate build directory
cd walberla
mkdir build
cd build

# set up the build system
cmake ..

# modify the configuration if necessary
ccmake .       # or alternatively "cmake-gui . "

# compile the code
make -j 4


# CMake Build Variables

To modify the build configuration go to your build directory and type ccmake . or cmake-gui .

Some commonly-used build variables:

Build variable Default Meaning
CMAKE_BUILD_TYPE Release Either Debug (non optimized, for debugging with asserts), Release (production runs), DebugOptimized (optimized, but for debugging with asserts), or RelWithDebInfo (Release with debug infos)
WALBERLA_ENABLE_GUI OFF Builds the graphical user interface. Make sure you have QT development libraries installed.
WALBERLA_BUILD_TUTORIALS ON Builds all the tutorials located in "apps/tutorials" (= they are added to the 'all' target in the Makefile). If disabled, the tutorials can still be built by going to "apps/tutorials" in the build folder and running make.
WALBERLA_BUILD_WITH_MPI ON Since one main goal of waLBerla are massively parallel simulations, this is enabled by default. However, MPI can be disabled.
WALBERLA_BUILD_WITH_OPENMP OFF Enables/Disables OpenMP support for thread-parallel computation. Can also be combined with MPI for hybrid simulations!
WALBERLA_BUILD_TESTS OFF If enabled, all tests are built when running make in the root build folder. But you can always go to a specific directory in your test folder and manually run make.
WALBERLA_BUILD_BENCHMARKS ON Enables/Disables the automatic build of all benchmarks located in "apps/benchmarks".
WALBERLA_BUILD_WITH_PYTHON OFF Enables Python Support inside waLBerla (embedded Python). Then you can use Python scripts as configuration files and start an embedded python interpreter that can access waLBerla data structures.
WALBERLA_BUILD_WITH_PYTHON_MODULE OFF This builds a shared library (and python module) walberla.so in "apps/pythonmodule" so that you can use walberla from python.

For a list of all switches, see CMakeLists.txt in the root source folder.

# Building waLBerla with Python

There are multiple ways for waLBerla to interact with Python: first a waLBerla C++ application can be built with Python support such that it can be scripted through the config file. In addition to the normal text-based config, such a C++ app can also be called with a Python script that returns configuration options and optionally installs hooks for e.g. geometry setup, post-processing or steering. This mode can be enabled by the CMake variable WALBERLA_BUILD_WITH_PYTHON.

While in this first option the driving code is C++, the second option exports most of waLBerlas functionality as a Python module that can be imported from a regular Python script. Thus the application itself can be written in Python. To build and install the waLBerla Python module enable WALBERLA_BUILD_WITH_PYTHON and WALBERLA_BUILD_WITH_PYTHON_MODULE. Then run 'make pythonModule' to build and 'make pythonModuleInstall' to install the module in your current environment.

The third option is code generation using 'pystencils' and 'lbmpy' and is covered later.

## Installing Python dependencies.

Both variants described above introduce dependencies on the Python and the boost::python library. We support building against Python in version 3.3 and above. On Ubuntu install 'python3-dev' and 'libboost-python-dev'. Then CMake automatically finds the right libraries.

On clusters the setup process can be more complicated. Usually boost has to be compiled manually there. One very common problem then is to not link boost::python against the same python lib as waLBerla is linked against. For example when boost python is built against Python2 and waLBerla linked against Python3, linker errors occur. You can test what your boost python was linked against with 'grep -rl "PyString_Type" libbboost_python'. If something is found, it was built against Python2, if not, against Python3.

To build boost correctly against a certain Python version do:

./bootstrap.sh --with-python=/path/to/python3 --with-python-root=/base/dir/with/lib/and/include/ --with-python-version=3.Xm


To be on the safe side then edit the project-config.jam and adapt the following line (here for example python3.6m) by entering the location of the interpreter, include path and lib path:

using python : 3.6 : /path/to/python3 : /python/root/include/python3.6m/ : /python/root/lib/ ;


Then build with

./b2 -j $NUM_PROCS toolset=$TOOLSET install --prefix=\$PREFIX


Don't forget to set BOOST_ROOT such that CMake finds your custom boost library.

# Setup of Integrated Development Environments

## Eclipse

If you use eclipse (http://www.eclipse.org/) for development, you can use the provided files in "utilities/eclipse" to setup your environment. For details see Setup Eclipse

## Visual Studio

If you use Visual Studio (https://www.visualstudio.com/) for development, add the appropriate generator flag when running CMake for the first time.

  # create a separate build directory
cd walberla
mkdir build
cd build

# set up the build system for Visual Studio
cmake -G "Visual Studio 14 2015 Win64" ..
# find other versions at https://cmake.org/cmake/help/latest/manual/cmake-generators.7.html#visual-studio-generators

# modify the configuration if necessary
ccmake .       # or alternatively "cmake-gui . "


Now you can open the file walberla.sln in Visual Studio.

## Xcode

If you use Xcode (https://itunes.apple.com/app/xcode/id497799835) for development, add the appropriate generator flag when running CMake for the first time:

  # create a separate build directory
cd walberla
mkdir build
cd build

# set up the build system for Xcode
cmake -G "Xcode" ..

# modify the configuration if necessary
ccmake .       # or alternatively "cmake-gui . "


Now you can open the file walberla.xcodeproj.