This project provides matrix-free high-performance solver for coupled simulations: a hyper-elastic solid solver for coupled fluid-structure interactions, which was primarily developed on the basis of the 'large-strain-matrix-free' project, and a heat solver describing the thermal diffusion in a rigid body. The startin point of this project was given by the matrix-based coupled codes in the 'dealii-adapter' project. Special thanks goes to @peterrum for his valuable deal.II advice at all times.
The program builds on the finite-element library deal.II and the coupling library preCICE and includes the following capabilities:
- matrix-free
- geometric multigrid preconditioner
- fully implicit coupling
- subcycling
- arbitrary number of interface nodes
- selectable interface node location
- mpi parallelism and vectorization
The solid mechanics solver:
- nonlinear hyperelastic neo-Hookean material
- Newton-Raphson method
- Newmark time integration
The heat diffusion solver:
- backward Euler time integration
In order to build the program, both libraries (deal.II and preCICE) need to be installed on your system:
At least version 9.4 (9.3 might work as well, but this version in not tested any more) or greater is required. Compatibility for older deal.II versions and corresponding older repository versions might be available thorugh the list of releases. You can use the following command line instructions in order to download and compile deal.II. Note that the library relies on p4est in order to handle distributed meshes and you need to adjust the P4EST_DIR according to your installation. If you have not yet installed p4est, you might want to download the latest tarball and run the p4est-setup.sh script located in your deal.II directory at dealii/doc/external-libs. In order to compile p4est properly, the script might require you to export the mpi wrapper before starting it: export CC=mpicc and export CXX=mpicxx. On Linux-based systems, the candi (compile & install) script offers help for the installation process. A complete installation guide including all installation options is also given on the deal.II installation page.
git clone https://github.com/dealii/dealii.git
mkdir build && cd build
cmake \
-D CMAKE_BUILD_TYPE="DebugRelease" \
-D CMAKE_CXX_FLAGS="-march=native -std=c++17" \
-D DEAL_II_CXX_FLAGS_RELEASE="-O3" \
-D DEAL_II_WITH_MPI="ON" \
-D DEAL_II_WITH_P4EST="ON" \
-D P4EST_DIR="../path/to/p4est/installation" \
-D DEAL_II_WITH_LAPACK="ON" \
-D DEAL_II_WITH_HDF5="OFF" \
-D DEAL_II_WITH_MUPARSER="ON" \
-D DEAL_II_COMPONENT_EXAMPLES="OFF" \
..
make -j8
At least version 3.0 or greater is required. A nice overview of various installation options is given on the preCICE installation page.
Similar to the deal.II programs, run
mkdir build && cmake -DDEAL_II_DIR=/path/to/deal.II -Dprecice_DIR=/path/to/precice ..
in this directory to configure the problem. The explicit specification of the library locations can be omitted if they are installed globally or via environment variables. You can then configure the program in debug mode or release mode by calling either make debug or make release. Afterwards, run make solid in order to build the solid mechanics FSI solver, make heat in order to build the thermal diffusion heat solver or just make in order to build both solvers. Exemplary parameter files for each individual solver can be found in the root directory of this repository (elasticity.prm for the FSI solver, heat_transfer.prm for the heat solver) or in the ./examples directory, which contains application examples. Note that the polynomial degree and the applied quadrature formula (both can be specified in the parameter files) are templated within the program. By default, common polynomial degrees (1-6) and corresponding common quadrature orders are supported. However, both template parameters can be modified in the ./include/base/fe_integrator.h file. More information about the templating of these parameters and their selection can be found in the corresponding deal.II documentation.
Compiling the program generates two executables: solid and heat. In order to run a simulation, add the location of your executable to your PATH environment variable or copy the executable directly into the simulation directory. Afterwards, configure your case using the parameter file, e.g. elasticity.prm and start the case, e.g. using four processes, by running
mpirun -np 4 ./solid elasticity.prm
The programs generates vtu output files after every Output tick of simulation time and stores them in the Output folder, which can be specified in the parameter file. The vtu format can be visualized with common visualization software supporting vtk files such as ParaView or VisIt. However, the results are written using higher_order_cells by default and a sufficiently recent version of these software packages supporting the higher-order feature is required to visualize the files (e.g. starting fromParaview version 5.5.0). If necessary, writing higher-order cells can easily be disabled in the source code.
All test cases are located in the (sub)directory ./include/cases/. You can add your own case by copying one of the existing cases or editing the ./include/cases/case_template.h file. Have a look at the description in the respective files for further information. Afterwards, you need to add your new case to the ./include/cases/case_selector.h and recompile the program.
If you still have questions, you can ask them preferably on GitHub discussions here or alternatively in one of the preCICE community channels.