Advanced Finite Difference flow solver with Multiple Resolution and Phase-Field implementations
AFiD has the following prerequisites that must be installed to compile and run the program:
- A parallel HDF5 library wrapping an MPI implementation and a Fortran 90 compiler
- The numerical LAPACK library (or Intel MKL)
- FFTW3 (not the MKL implementation)
On Ubuntu, these prerequisites can be installed using the single line command
sudo apt install build-essential gfortran liblapack-dev libhdf5-openmpi-dev libfftw3-dev
AFiD can then be compiled simply by running make.
The Makefile contains a MACHINE variable and a FLAVOUR variable that the user can modify to reflect the libraries installed (e.g. setting FLAVOUR=Intel ensures the MKL libraries and Intel compiler options are used).
Presets are also available for a collection of European HPC systems using the MACHINE variable.
- Third-order Runge-Kutta time stepping
- Finite-differences calculate spatial derivatives on staggered velocity grid
- Pencil MPI decomposition based on the 2DECOMP&FFT library
- Cubic Hermite interpolation between two decoupled grids for multiple resolution
- Phase-field model to simulate the flow around melting objects following Hester et al. (2020)
- Immersed boundary method for fixed objects following Fadlun et al. (2000)
- A simple moisture model for a rapidly condensing vapour field following Vallis et al. (2019)
AFiD is a highly parallel application for simulating canonical flows in a channel domain. More technical details can be found in van der Poel et al (2015). The code is developed jointly by the University of Twente, SURFsara, and the University of Rome "Tor Vergata".
In addition to the method described in van der Poel et al (2015), this multi-resolution version of AFiD evolves a second scalar field. This scalar field is simulated on a refined grid to allow for low diffusivity values or high Schmidt numbers. The multi-resolution method applied is detailed in Ostilla-Monico et al (2015) and was implemented into AFiD by @chongshenng. Interpolation between the two grids is performed using a four-point Hermite interpolation scheme.
One key difference from the original version of AFiD is that the scalar fields are evaluated at the mid-points of the computational cells. This staggered grid provides more flexibility for applications with different gravitational axes.
The refined grid can also be used to evolve a phase-field variable to model the melting and dissolving of immersed solid objects.
If you would like to contribute to bug fixing/feature development/documentation, please create a new branch, commit your changes and then submit a pull request.