nsfds2 0.8.4

Finite difference solver for Navier-Stokes equations

nsfds2 : 2D Navier-Stokes Finite Differences Solver

Introducing nsfds2

nsfds2 is 2D Navier-Stokes Solver that uses finite difference method.

nsfds2 is still in developpement.

Dependencies

• python > 3.6
• numpy
• matplotlib
• h5py
• progressbar33
• ofdlib2
• fdgrid
• mplutils

Installation

python setup.py install

or

pip install nsfds2

Classical use

nsfds2 can be used from a terminal with :

nsfds2 solve|movie|show

• solve : solves Navier-Stokes equation using default config file ~/.nsfds2/nsfds.conf
• movie : makes movie from results obtained with solve subcommand
• show : shows simulations parameters and grid

Custom Use

import matplotlib.pyplot as plt
from nsfds2.init import CfgSetup, Fields
from nsfds2.fdtd import FDTD
from nsfds2.utils import graphics
from fdgrid.mesh import Mesh

# Read simulation parameter in config file ~/nsfds2/nsfds2.conf
cfg = CfgSetup()

# Define the mesh
msh = Mesh((cfg.nx, cfg.nz), (cfg.dx, cfg.dz), origin=(cfg.ix0, cfg.iz0), obstacles=[])

# Init acoustic fields
fld = Fields(msh, cfg)

# Create simulation
fdtd = FDTD(msh, fld, cfg)
fdtd.run()

# Figures
plt.figure()
plt.imshow(fld.p)
plt.show()

Config file

[configuration]
timings = True|False 			# Display timings
quiet = True|False 			# Quiet mode

[simulation]
nt = 500 				# Number of time iterations
ns = 10 				# Save each ns iterations
cfl = 0.5 				# Courant–Friedrichs–Lewy number

[geometry]
mesh = regular|curvilinear		# Mesh type
file = None|path 			# Path to python file (geometry)
geoname = helmholtz_double 		# Python function for geometry
curvname = curvz			# Python function for curvilinear coordinates
bc = ARRA 				# Boundary conditions. Must be a mix of ARP
nx = 256				# Number of grid points along x-axis
nz = 256				# Number of grid points along z-axis
ix0 = 128 				# Origin of the grid
iz0 = 0					# Origin of the grid
dx = 1e-4				# Spatial x-step
dz = 1e-4 				# Spatial z-step

[PML]
beta = 0.0 				# Depends on pseudo mean flow profile
alpha = 4.0 				# Order of the spatial repartition law
sigmax = 20 				# Filter strength along x
sigmaz = 20 				# Filter strength along z
npml = 15				# Number of points of the PML

[source]
type = pulse|harmonic|white 		# Source type
ixs = 64				# Source x-location
izs = 128 				# Source z-location
s0 = 1e6 				# Sources strength
B0 = 2 					# Half spatial bandwidth
f0 = 60000 				# Frequency (only for harmonic)

[eulerian fluxes]
stencil = 3|7|11 			# Number of points of stencil

[filtering]
filter = True|False 			# Activate selective filter
stencil = 11 				# Number of points of stencil used by filter
stength = 0.75 				# Strength of the filter

[viscous fluxes]
viscosity = True|False 			# Activate viscosity
stencil = 7 				# Number of points of stencil

[shock capture]
shock capture = True|False 		# Activate shock capture procedure
stencil = 7 				# Number of points of stencil
method = pressure|dilatation 		# Capture based on pressure or dilatation

[figures]
figures = True|False 			# Activate figures

[save]
save = True|False 			# Activate save
path = results 				# Path to data file
filename = tmp 				# Data filename
compression = None|lzf 			# Activate compression
only p = True|False			# Save only pressure
probes = True|False                     # Activate probes
probes_locations = [[128, 128], [128, 192]] # Probe locations. Must be list of lists

Changelog

0.8.4

• new: white noise pressure source

0.8.3

• new: harmonic pressure source

0.8.2

• fix: compatibility with jupyter notebook

0.8.1

• chg: mpltools to mplutils

0.8.0

• Changes in ofdlib2 & fdgrid

0.7.2

• minor changes

0.7.1

• fdgrid 0.6.4 changes : plot_obstacles -> plot_subdomains

0.7.0

• Curvilinear mesh official support

0.6.1

• ... with readme...
• Start to adapt code for adaptative/curvi. meshes

0.6.0

• Minor changes
• Fix no action specified issue.
• argparse + entry point

0.5.2

• Some minor changes about structure

0.5.1

• Probes added

0.5.0

• PML support

0.4.7

• Update for fdgrid 0.5.0
• Bugfixes

0.4.6

• Obstacles checking added

0.4.5

• Fix periodic boundaries

0.4.4

• Adapted to ofdlib2 v0.7

0.4.3

• README updated

0.4.2

• Check source location

0.4.1

• Fix capture + h5py deprecation warining

0.4.0

• Dispatch viscous flux
• minor changes
• Changes in config

0.3.0

• Dispatch capture + Minor changes

0.2.2-dev0

• dilatation + minor changes

0.2.1-dev0

• Minor changes. Patches removed.

0.2.0-dev0

• cin & sfilter simplified

0.1.3-dev0

• Filtering simplified

0.1.2-dev0

• minor changes

0.1.1-dev0

• Start patches
• Convert some functions to 'in-place function'
• Adaptated to ofdlib2 changes
• Upgraded to ofdlib2
• Viscosity basics
• First commit