Building and running Kratos with CoSimulation

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Before starting the connection to Kratos one should build the Kratos with the necessary applications. Please check the Kratos install guide for more information about the Kratos build requirements and options. Here only a brief overview is provided.

The easiest way to build the Kratos would be using the standard_configure files provided in the scripts folder. These scripts would provide the Kratos core library but not the required CoSimulation application and (optional but useful) Mapping application. For adding them you may copy for instance the standard_configure.sh to cosimulation_configure.sh and adding these two applications (you may keep or remove the rest):

# Set applications to compile
export KRATOS_APPLICATIONS=
add_app ${KRATOS_APP_DIR}/CoSimulationApplication
add_app ${KRATOS_APP_DIR}/MappingApplication

Now for running the Kratos, one should configure the python environment variables as follows:

• PYTHONPATH should point to the Kratos binaries root (path/to/kratos) where you can find KratosMultiphysics sub folder
• LD_LIBRARY_PATH should point to the libs folder (path/to/kratos/libs) where you can find compiled libraries.

After building Kratos it can be run like a regular python script:

python3 MainKratos.py

With MainKratos.py typically starting with the imports of Kratos at the top of the script, same procedure as is done with other python modules:

import os # importing a standard python module

import KratosMultiphysics # importing the Kratos Core

# importing the applications
from KratosMultiphysics import CoSimulationApplication
from KratosMultiphysics import MappingApplication

Building and running Kratos with MPI support

For mpi-distributed coupled simulations it is necessary to compile Kratos with MPI support. This can be done by setting the CMake configure flag:

-DUSE_MPI=ON

See also the Kratos install guide for MPI support.

Running Kratos in MPI is slightly different from the serial execution. Aside from launching Kratos with mpiexec (or mpirun) it is important to pass the --using-mpi flag:

mpiexec -np 4 python3 MainKratos.py --using-mpi

Now the MPI Core of Kratos (KratosMultiphysics.mpi) is available and can be imported and used:

import KratosMultiphysics # importing the Kratos Core
import KratosMultiphysics.mpi as KratosMPI # importing the Kratos MPICore

# importing the applications
from KratosMultiphysics import CoSimulationApplication
from KratosMultiphysics import MappingApplication