FluTAS (Fluid Transport Accelerated Solver) is a modular, multiphysics code for multiphase fluid dynamics simulations. The code is written in a modular way, to easily accomodate different physics into the system. One of the main purposes of the project is to provide an efficient framework able to run both on many-CPUs (MPI) and many-GPUs (MPI+OpenACC+CUDA Fortran). The code has been tested on several large-scale HPC clusters.

This effort initiated within the research group of Prof. Luca Brandt at KTH. The code structure and the Poisson solver are based on CaNS (https://github.com/p-costa/CaNS), and have been adapted to include the different modules developed by the various researchers and students at KTH Engineering Mechanics.

References

Method and single-phase solver:
P. Costa. A FFT-based finite-difference solver for massively-parallel direct numerical simulations of turbulent flows. Computers & Mathematics with Applications 76: 1853--1862 (2018). doi:10.1016/j.camwa.2018.07.034 [arXiv preprint]

GPU extension:
P. Costa, E. Phillips, L. Brandt & M. Fatica, GPU acceleration of CaNS for massively-parallel direct numerical simulations of canonical fluid flows Computers & Mathematics with Applications (2020). doi.org/10.1016/j.camwa.2020.01.002 [arXiv preprint]

• not yet...to come!

Current physics modules implemented:

• Base solver for the incompressible two-fluid Navier-Stokes equations;
• Multiphase flows, using the VoF MTHINC method;
• Heat Transfer, solving the energy equation (Boussinesq effects can be included in the gas phase).

Some features are:

• MPI parallelization
• FFTW guru interface used for computing multi-dimensional vectors of 1D transforms
• The right type of transformation (Fourier, Cosine, Sine, etc) automatically determined from the input file
• 2DECOMP&FFT routines used for performing global data transpositions and data I/O
• A different canonical flow can be simulated just by changing the input files

Some examples of the flows that can be solved by FluTAS are:

• periodic or spatially developing channel
• periodic or spatially developing square duct
• tri-periodic domain
• lid-driven cavity
• homogeneous and isotropic turbulence
• Rayleigh–Bénard convection

for more details, please refer to HOW_TO_USE.md

The code should be compiled in src/. The prerequisites are the following:

• MPI
• FFTW3
• OpenMP (optional)

and for the GPU version:

• NVIDIA Fortran compiler (https://developer.nvidia.com/hpc-sdk)
• cuFFT from the CUDA toolkit

Further technical informations are provided in HOW_TO_USE.md.

Run the executable with mpirun with a number of tasks and shared threads complying to what has been set in the input file dns.in. Data will be written by default in a folder named data/, which must be located where the executable is run.

See INFO_VISU.md.

We appreciate any feedback to improve the code. Also, feel free to send case files pertaining to flows not listed in the examples folder. Please read the ACKNOWLEDGEMENTS.md and LICENSE files.

If you are interested in contributing to this effort, please get in contact with Luca Brandt.