LBM with SCFT

Implementation of Lattice Boltzmann in 3D using D3Q15 that also solves the field equations for a polymer chain.

Lattice Boltzmann Implementation

1. Implementation, initialises using the equilibrium distribution.

2. Time Step Algorithm

• Macroscopic moments are computed
• Equilibrium distribution is calculated.
• The macroscopic fields density and fluid speed is written to hard disk for visualisation or post processing.
• Colllision relaxation is performed.
• Streaming is done.
• The time step is incremented and repeat the time step algorithm.

Implemeted using The Lattice Boltzmann Method Principles and Practice. ISBN: 978-3-319-44647-9 SCFT solver implemented using "Lattice Boltzmann method for multiscale self-consistent field theory simulations of block copolymers" by: Hsieh Chen, YongJoo Kim, and Alfredo Alexander-Katz and "Lattice Boltzmann study of pattern formation in reaction-diffusion" by: S.G. Ayodele1, F. Varnik and D. Raabe

Lees-Edwards boundary conditions implemented using: "Lees-Edwards boundary conditions for lattice Boltzmann suspension simulations" by: Eric Lorenz and Alfons G. Hoekstra. As well as: "Lees-Edwards boundary conditions for Lattice Boltzmann" by: Alexander J. Wagner and Ignacio Pagonabarraga.

To build

To build. Clone repo. Then mkdir build
cd build
cmake ..
make

Projects used in this

• RapidJSON (https://github.com/Tencent/rapidjson)
• fast-cpp-csv-parser (https://github.com/ben-strasser/fast-cpp-csv-parser)
• Catch2 (https://github.com/catchorg/Catch2)

To visualise

Run the simulation, then once it has ran. Run the visualise MATLAB script and it will then generate figure images and interactive figures in MATLAB.

Notes

options.json must be copied to the build folder currently.
The options.json has save_every option which generates a CSV file of the density and velocity fields for the current timestep % save_every. So a save_every of 550 will generate 0.csv,50.csv,100.csv and so forth. Grid size is the grid of the field to visualise size. Velocity set can either be D3Q15 or D3Q27. c_s can be adjusted as different velocity sets may have alternate speed of sounds.

Cloning instructions

git clone https://github.com/callummarshall9/LBM_3D_SCFT.git
git submodule update --init --recursive