goktug97 / LatticeBoltzmannSimulation

Python Implementation of Lattice Boltzmann Method

Lattice Boltzmann Simulation

Requirements

numpy
matplotlib
mpi4py

Usage

All commands must be run in the project root.

git clone https://github.com/goktug97/LatticeBoltzmannSimulation
pip install -r requirements.txt

# Single thread
PYTHONPATH="$(pwd):$PYTHONPATH" python simulations/karman_vortex.py

# Parallel
PYTHONPATH="$(pwd):$PYTHONPATH" mpirun -np 2 python simulations/karman_vortex.py

Check simulations folder for more examples.

import numpy as np
import matplotlib.pyplot as plt

import lb


nx = 50
ny = 50
n_steps = 3000
w = 0.3

x, y = np.meshgrid(np.arange(nx), np.arange(ny))

density = np.ones((ny, nx), dtype=np.float32)
velocity_field = np.zeros((ny, nx, 2), dtype=np.float32)
velocity_field[:, :, 1] = np.sin(2*np.pi/ny*y)

lbs = lb.LatticeBoltzmann(density, velocity_field)

for step in range(n_steps):
    print(f'{step+1}\\{n_steps}', end="\r")

    lbs.stream_and_collide(tau=1/w)

    if not step % 100:
        plt.cla()
        lbs.plot()
        plt.pause(0.001)

Experiments

All commands must be run in the project root. All results are saved into results folder.

Shear Wave Decay Experiment

PYTHONPATH="$(pwd):$PYTHONPATH" mpirun -np 2 python experiments/shear_decay.py

Velocity Decay

Step 0	Step 200	Step 400
Step 600	Step 800	Step 1000
Step 1200	Step 1400	Step 1600
Step 1800	Step 2000	Step 2999

Density Decay

Step 0	Step 200	Step 400
Step 600	Step 800	Step 1000
Step 1200	Step 1400	Step 1600
Step 1800	Step 2000	Step 2999

Shear Wave Simulated vs Analytical Viscosity

PYTHONPATH="$(pwd):$PYTHONPATH" mpirun -np 2 python experiments/shear_wave_viscosity.py

Density	Velocity

Couette Flow

PYTHONPATH="$(pwd):$PYTHONPATH" mpirun -np 2 python experiments/couette_flow.py

Step 0	Step 200	Step 400
Step 600	Step 800	Step 1000
Step 1200	Step 1400	Step 1600

Poiseuille Flow

PYTHONPATH="$(pwd):$PYTHONPATH" mpirun -np 2 python experiments/poiseuille_flow.py

Step 0	Step 400	Step 800
Step 1200	Step 1600	Step 2000
Step 2400	Step 3200	Step 3999

Lid-driven Cavity

PYTHONPATH="$(pwd):$PYTHONPATH" mpirun -np 2 python experiments/sliding_lid.py

Step 0	Step 20000	Step 40000
Step 60000	Step 80000	Step 99999