aste stands for Artificial Solver Testing Environment for preCICE. aste facilitates getting data into preCICE and out of it. An overview is given by the following figure:

aste consists of compiled C++ Modules and of Python modules.

Create a simple text mesh on [x0, x1] x [y0, y1] with nx x ny points. The mesh is 3-dimensional, with the z-component set to 0.

Reads a mesh as either .vtk or .txt and evaluates a function given by -f on it. The function gets the mesh points a numpy array of the form x = [[x_1, y_1, z_1], ...] and should store the result in y.

Reads a mesh as either .vtk or .txt, partitions it and stores the parts in a directory like dirname/0, 1, .... For partitioning two algorithms are available. The meshfree algorithm does not need any mesh topology information, whereas the topological algorithm needs topology information. This python module needs the C++ module libmetisAPI.so if the topological algorithm is used.

Reads a partitioned mesh from a directory like dirname/0, 1, ... and saves it to a single file.

This is a small C++ wrapper around METIS. It is only required if partition_mesh.py should use a topological algorithm.

This is a C++ application, which does the coupling through precice. It expects a mesh in the format given by partition_mesh.py. currently, only explict coupling is supported. When using multiple timesteps, make sure to provide a mesh (with data) for each timestep.

• preCICE
• MPI
• CMake

• METIS

• NumPy

• vtk (Visualization Toolkit)
• scipy

Make sure to have all the needed dependencies installed. Then do:

mkdir build
cd build
cmake ..
make

If precice is not installed in $PRECICE_ROOT/build do cmake -DCMAKE_LIBRARY_PATH=$PRECICE_INSTALL_DIR .. with the correct installation directory.

Initialize environment, e.g., put in your .bashrc

# METIS for aste
module load metis
export METIS_DIR=$METIS_BASE # so that cmake finds metis
export CPLUS_INCLUDE_PATH="$METIS_BASE/include:$CPLUS_INCLUDE_PATH"

and execute cmake like cmake -DCMAKE_C_COMPILER=gcc -DCMAKE_CXX_COMPILER=g++ .. and make.

A simple demonstration of aste can be run with ./demo.sh. A bunny-shaped mesh is mapped onto a red blood cell. The result can be seen in result.vtk.

A similar demo with multiple timesteps can be run with ./timesteps.py inside contrib/timestep-demo. Make sure to set astedir inside timesteps.py to the correct value (By using the environment variable ASTEDIR). For details look into the timesteps.py and the corresponding timesteps-precice.xml file.