Fourier Accelerated Nodal Solvers (FANS)

Fourier Accelerated Nodal Solvers (FANS) is an FFT-based homogenization solver designed to handle microscale multiphysics problems. This repository contains a C++ implementation of FANS, built using CMake and MPI for parallel computations.

Table of Contents

• Installation
• Usage
• Input File Format
• Example

Installation

Prerequisites

Before proceeding with the installation, ensure that your system has the necessary dependencies. The prerequisites of FANS can be installed using Spack for a streamlined setup on high-performance computing systems, or through traditional package management for personal use.

Spack Installation (Recommended for Clusters/Supercomputers)

Spack is a package manager designed for high-performance computing environments. It simplifies the installation of complex software stacks, making it ideal for setting up FANS on large clusters or supercomputers.

1. Install Spack: If you don’t have Spack installed, you can set it up with the following commands:

   git clone https://github.com/spack/spack.git
   cd spack/bin
   source ./spack

2. Install Dependencies: Once Spack is set up, you can install the required dependencies:

   spack install cmake
   spack install mpi
   spack install hdf5 +cxx +mpi
   spack install eigen
   spack install fftw +mpi

   You can also use alternative and optimized FFTW implementations depending on your system's architecture like amdfftw (For AMD systems) or cray-fftw (For Cray systems) or fujitsu-fftw (For Fujitsu systems).

3. Load Dependencies Once dependencies are installed, you can load them before building:

   spack load cmake mpi hdf5 eigen fftw

Traditional Installation

If you're setting up FANS on a personal computer or in a non-HPC environment, follow these instructions:

Please ensure you have the following dependencies installed on your system:

• CMake (version 3.0 or higher)
• MPI (mpicc and mpic++)
• HDF5 with parallel support
• Eigen3
• FFTW3 with MPI support

Specifically, to run FANS, you at least need the following packages:

openmpi-bin libc6 libfftw3-double3 libfftw3-mpi3 libgcc-s1 libgomp1 libhdf5-103 libopenmpi3 libstdc++6

To build fans, you additionally need these packages:

libhdf5-dev libopenmpi-dev libeigen3-dev libfftw3-dev libfftw3-mpi-dev

If for some reason you are unable to install these packages directly on your host machine, have a look at the set of Docker images to create and work with FANS within an isolated environment.

Building the Project

1. Clone the repository:

   git clone https://github.tik.uni-stuttgart.de/DAE/FANS.git
   cd FANS

2. Configure the project using CMake:

   mkdir build
   cd build
   cmake ..

3. Compile the project:

   cmake --build . -j

The compilation will symlink the generated FANS binary into the test/ directory for convenience.

Build Options

This project supports the following CMake build options:

• CMAKE_BUILD_TYPE: Sets the build type. Common values are Debug, Release, RelWithDebInfo, and MinSizeRel.

• FANS_BUILD_STATIC: Build static library instead of shared library.

  • Default: OFF
  • Usage: -DFANS_BUILD_STATIC=ON

• CMAKE_INTERPROCEDURAL_OPTIMIZATION: Enable interprocedural optimization (IPO) for all targets.

  • Default: ON (if supported)
  • Usage: -DCMAKE_INTERPROCEDURAL_OPTIMIZATION=OFF
  • Note: When you run the configure step for the first time, IPO support is automatically checked and enabled if available. A status message will indicate whether IPO is activated or not supported.

Installing the Project

After compiling, you can install FANS (system-wide) using the following options:

1. Using CMake (sudo required if --prefix is omitted):

   cmake --install . [--prefix <install-dir>]

2. Using .deb packages (only debian based distros; sudo required):

   cpack -G "DEB"
   apt install packages/fans_<version>_<architecture>.deb
   apt install packages/fans-dev_<version>_<architecture>.deb

Usage

To run the FANS solver, you need to provide a JSON input file specifying the problem parameters.

Input File Format

The input file is in JSON format and contains several fields to define the problem settings:

• ms_filename: Path to the microstructure file (HDF5 format).
• ms_datasetname: Path to the dataset inside the HDF5 file.
• ms_L: List defining the domain size.
• matmodel: Material model (e.g., ThermalLinear, MechLinear, HyperElastic).
• material_properties: Material properties relevant to the chosen material model.
• problem_type: Type of the problem (thermal or mechanical).
• method: Solution method (fp for fixed point or cg for conjugate gradient).
• TOL: Tolerance for the solver.
• n_it: Maximum number of iterations.
• g0: Macroscale loading vector.

Example

To run a linear elastic mechanical homogenization problem for a single load case on a microstructure image of size 256 x 256 x 256 with a single spherical inclusion,

mpiexec -n 1 ./FANS input_files/sphere_mech.json

Acknowledgements

Funded by Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy - EXC 2075 – 390740016. Contributions by Felix Fritzen are funded by Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) within the Heisenberg program - DFG-FR2702/8 - 406068690; DFG-FR2702/10 - 517847245 and through NFDI-MatWerk - NFDI 38/1 - 460247524. We acknowledge the support by the Stuttgart Center for Simulation Science (SimTech).