Closed GenB31415 closed 2 years ago
flaport
commented
2 years ago Hey @GenB31415 ,
Moving sources is not really supported by this package. However you can probably hack it as follows:
# define the position x, y and z of the source at each time t here:
x = ...
y = ...
z = ...
t = ...
for i, t in enumerate(t):
grid.step()
source = grid.sources.pop(-1) # make sure the source is no longer part of the grid
grid[x[i], y[i], z[i]] = source
GenB31415
commented
2 years ago Dear author, many thanks for the idea.I did that but I the error is generated: The grid already has an attribute with name pointsource My code is bellow (slightly modified code 01-basic-example.py ). Please let me know how to overcome this issue. Thank you. import matplotlib.pyplot as plt import fdtdimport fdtd.backend as bdfdtd.set_backend("numpy")# ConstantsWAVELENGTH = 1550e-9SPEED_LIGHT: float = 299_792_458.0 # [m/s] speed of light# Simulation# create FDTD Gridgrid = fdtd.Grid( (2.5e-5, 1.5e-5, 1), grid_spacing=0.1 * WAVELENGTH, permittivity=1.0, permeability=1.0,)
grid[:, :, 0] = fdtd.PeriodicBoundary(name="zbounds")
grid[11:32, 30:84, 0:1] = fdtd.AnisotropicObject(permittivity=2.5, name="object")
for i, t in enumerate(t): grid.step() posX = x0-velocity*t # <---- move source in next position x at time increase posY = y0 # <---- fixed position y posZ = z0 # <---- fixed position t source = grid.sources.pop(-1) # make sure the source is no longer part of the grid grid[posX, posY, posZ] = source # <--- Error: The grid already has an attribute with name pointsource # *** - - - - - end- - - - - - - - -
fields = bd.stack( [ grid.E[:, :, 0, 0], grid.E[:, :, 0, 1], grid.E[:, :, 0, 2], grid.H[:, :, 0, 0], grid.H[:, :, 0, 1], grid.H[:, :, 0, 2], ]) m = max(abs(fields.min().item()), abs(fields.max().item())) for ax, field, title in zip(axes.ravel(), fields, titles): ax.set_axis_off() ax.set_title(title) ax.imshow(bd.numpy(field), vmin=-m, vmax=m, cmap="RdBu") plt.show() plt.figure()grid.visualize(z=0)
On Monday, August 23, 2021, 09:21:48 AM CDT, Floris Laporte ***@***.***> wrote: Hey @GenB31415 ,
Moving sources is not really supported by this package. However you can probably hack it as follows:
x = ... y = ... z = ... t = ...
for i, t in enumerate(t): grid.step() source = grid.sources.pop(-1) # make sure the source is no longer part of the grid grid[x[i], y[i], z[i]] = source — You are receiving this because you were mentioned. Reply to this email directly, view it on GitHub, or unsubscribe. Triage notifications on the go with GitHub Mobile for iOS or Android.
GenB31415
commented
2 years ago (repetition) Dear @flaport , many thanks for the idea. I did that but I the error is generated: The grid already has an attribute with name pointsource
My code is bellow (slightly modified code 01-basic-example.py ). Please let me know how to overcome this issue. Thank you.
#fdtd.readthedocs.io/en/latest/examples/01-basic-example.html
import matplotlib.pyplot as plt
import fdtd
import fdtd.backend as bd
fdtd.set_backend("numpy")
# Constants
WAVELENGTH = 1550e-9
SPEED_LIGHT: float = 299_792_458.0 # [m/s] speed of light
# Simulation
# create FDTD Grid
grid = fdtd.Grid(
(2.5e-5, 1.5e-5, 1),
grid_spacing=0.1 * WAVELENGTH,
permittivity=1.0,
permeability=1.0,
)
# boundaries
# grid[0, :, :] = fdtd.PeriodicBoundary(name="xbounds")
grid[0:10, :, :] = fdtd.PML(name="pml_xlow")
grid[-10:, :, :] = fdtd.PML(name="pml_xhigh")
# grid[:, 0, :] = fdtd.PeriodicBoundary(name="ybounds")
grid[:, 0:10, :] = fdtd.PML(name="pml_ylow")
grid[:, -10:, :] = fdtd.PML(name="pml_yhigh")
grid[:, :, 0] = fdtd.PeriodicBoundary(name="zbounds")
# sources
# grid[50:55, 70:75, 0] = fdtd.LineSource(
# period=WAVELENGTH / SPEED_LIGHT, name="linesource"
# )
#grid[100, 60, 0] = fdtd.PointSource(
grid[120, 50, 0] = fdtd.PointSource(
period=WAVELENGTH / SPEED_LIGHT, name="pointsource",
)
# detectors
#grid[12e-6, :, 0] = fdtd.LineDetector(name="detector")
# objects
grid[11:32, 30:84, 0:1] = fdtd.AnisotropicObject(permittivity=2.5, name="object")
# - - - - - - start - - - - - - - -
# define the position x, y and z of the source at each time t here:
x0 = 120
y0 = 50
z0 = 0
tFin=50
t = range(0,tFin)
velocity = 0.1 # <---- velocity of a point source only in x direction
for i, t in enumerate(t):
grid.step()
posX = x0-velocity*t # <---- move source in next position x at time increase
posY = y0 # <---- fixed position y
posZ = z0 # <---- fixed position t
source = grid.sources.pop(-1) # make sure the source is no longer part of the grid
grid[posX, posY, posZ] = source
# - - - - - end- - - - - - - - -
# Run simulation
grid.run(tFin, progress_bar=False)
# Visualization
fig, axes = plt.subplots(2, 3, squeeze=False)
titles = ["Ex: xy", "Ey: xy", "Ez: xy", "Hx: xy", "Hy: xy", "Hz: xy"]
fields = bd.stack(
[
grid.E[:, :, 0, 0],
grid.E[:, :, 0, 1],
grid.E[:, :, 0, 2],
grid.H[:, :, 0, 0],
grid.H[:, :, 0, 1],
grid.H[:, :, 0, 2],
]
)
m = max(abs(fields.min().item()), abs(fields.max().item()))
for ax, field, title in zip(axes.ravel(), fields, titles):
ax.set_axis_off()
ax.set_title(title)
ax.imshow(bd.numpy(field), vmin=-m, vmax=m, cmap="RdBu")
plt.show()
plt.figure()
grid.visualize(z=0)You gave your source the name 'pointsource', so it's available as an attribute to the grid, i.e. grid.pointsource. In that case you also have to delete that attribute in the loop:
source = grid.sources.pop(-1)
del grid.pointsourceHey @flaport, thanks, now it works. The code (run or uncomment corresponding line)
import matplotlib.pyplot as plt
import fdtd
import fdtd.backend as bd
fdtd.set_backend("numpy")
OneMicron=1e-6
WAVELENGTH = OneMicron
LengthScale = OneMicron
SPEED_LIGHT: float = 299_792_458.0 # [m/s] speed of light
indRefr=1.15
grid = fdtd.Grid(
(25*LengthScale, 25*LengthScale, 1),
grid_spacing=0.1 * LengthScale, permittivity=indRefr**2, permeability=1.0,
)
grid[0:10, :, :] = fdtd.PML(name="pml_xlow")
grid[-10:, :, :] = fdtd.PML(name="pml_xhigh")
grid[:, 0:10, :] = fdtd.PML(name="pml_ylow")
grid[:, -10:, :] = fdtd.PML(name="pml_yhigh")
x0 = 17.0*LengthScale; y0 = 12.5*LengthScale; z0 = 0;
periodTime= LengthScale / SPEED_LIGHT
grid[x0, y0, z0] = fdtd.PointSource( period = periodTime )
# velocity of a point source only in x direction
#velocity = 0.69; tFin=20*1
#velocity = 0.6; tFin=20*1
#velocity = 0.5; tFin=20*1
#velocity = 0.3; tFin=20*2
velocity = 0.2; tFin=20*3
#velocity = 0.1; tFin=20*4
#velocity = 0.05; tFin=20*4
#velocity = 0.005; tFin=20*5
tAll = range(0, tFin)
for i, t in enumerate(tAll):
grid.step()
tt = t*LengthScale
posX = (x0-velocity*tt) # <---- move source in next position x when time increases
posY = y0 # <---- fixed position y
posZ = z0 # <---- fixed position z
source = grid.sources.pop(-1) # make sure the source is no longer part of the grid
source = fdtd.PointSource(period=periodTime, name=(f"Cher: i={i}"))
grid[posX, posY, posZ] = source
grid.run(tFin, progress_bar=False)
fig, axes = plt.subplots(2, 3, squeeze=False)
titles = ["Ex: xy", "Ey: xy", "Ez: xy", "Hx: xy", "Hy: xy", "Hz: xy"]
fields = bd.stack(
[
grid.E[:, :, 0, 0],
grid.E[:, :, 0, 1],
grid.E[:, :, 0, 2],
grid.H[:, :, 0, 0],
grid.H[:, :, 0, 1],
grid.H[:, :, 0, 2],
]
)
m = max(abs(fields.min().item()), abs(fields.max().item()))
import numpy as np
for ax, field, title in zip(axes.ravel(), fields, titles):
ax.set_axis_off()
ax.set_title(title)
ax.imshow(bd.numpy(field), vmin=-m, vmax=m, cmap="hsv")
plt.show()
plt.figure()
plt.title(source.name +f", v={velocity}, n={indRefr}")
grid.visualize(z=0,cmap="nipy_spectral_r",)great to hear it's working now :)
Dear author, many thanks for your interesting package! In my problem I have to study the field of a source moving with the uniform velocity along the grid. Is there any way to indicate the current position of the point source (depending on current time) while the field update? Thank you in advance.