Again two secondary sources, this time with sine waves.
"""
from __future__ import division
import numpy as np
import duct
duct.xMax = 10
freq = 50
waveLength = duct.c0 / freq
qp = 1
primSrc = duct.MonopoleSource(position=1,
generator=duct.SineGenerator(qp, freq),
name='Primary source')
d = 0.5
L = waveLength * 3/4
k = 2*np.pi / waveLength
qs2 = -qp * np.exp(-1j*k*L) / (2j*np.sin(k*d))
qs1 = -qs2 * np.exp(-1j*k*d)
secSrc1 = duct.MonopoleSource(position=1+L,
generator=duct.SineGenerator(qs1, freq),
name='Secondary source 1')
secSrc2 = duct.MonopoleSource(position=1+L+d,
generator=duct.SineGenerator(qs2, freq),
name='Secondary source 2')
"""
Monopole source is a good approximation for speaker mounted on the wall
of the duct if the wavelength of sound wave is much longer than the width
of duct.
"""
from __future__ import division
import numpy as np
import duct
freq = 50
#s = duct.MonopoleSource(position=1, generator=duct.PulseGenerator(amp=1, delay=0))
s = duct.MonopoleSource(position=1,
generator=duct.SineGenerator(q=0.001, freq=freq))
duct.animate([s])
duct.xMax = 10
# sine waves
if 0:
freq = 50
waveLength = duct.c0 / freq
k = 2 * np.pi / waveLength
q1 = 1
#L = waveLength/2 # cancelation in both directions
L = waveLength * 5 / 8
#L = waveLength * 3/4
#L = waveLength
q2 = -q1 * np.exp(-1j * k * L) # necessary for calculation
primSrc = duct.MonopoleSource(position=1,
generator=duct.SineGenerator(q1, freq))
secSrc = duct.MonopoleSource(position=1 + L,
generator=duct.SineGenerator(q2, freq))
# pulse
else:
primSrc = duct.MonopoleSource(position=3,
generator=duct.PulseGenerator(amp=1,
delay=0))
L = 2
delay = L / duct.c0
secSrc = duct.MonopoleSource(position=3 + L,
generator=duct.PulseGenerator(amp=-1,
delay=delay))
duct.animate([primSrc, secSrc])
Primary source radiates two rectangular pulses with opposite amplitude.
The result is ping pong pictured in figure 5.15 in the book.
"""
from __future__ import division
import numpy as np
import duct
duct.xMax = 10
L = 3
d = 1
amp = 0.01
primSrc_pulse1 = duct.MonopoleSource(position=1,
generator=duct.PulseGenerator(amp),
name='Primary source, 1st pulse')
primSrc_pulse2 = duct.MonopoleSource(position=1,
generator=duct.PulseGenerator(
-amp, 2 * d / duct.c0),
name='Primary source, 2st pulse')
secSrc1 = duct.MonopoleSource(position=1 + L,
generator=duct.PulseGenerator(
amp, (L + 2 * d) / duct.c0),
name='Secondary source 1')
secSrc2 = duct.MonopoleSource(position=1 + L + d,
generator=duct.PulseGenerator(
-amp, (L + d) / duct.c0),
name='Secondary source 2')
duct.animate([primSrc_pulse1, primSrc_pulse2, secSrc1, secSrc2])
unwanted reflections.
"""
from __future__ import division
import numpy as np
import duct
duct.xMax = 10
freq = 50
waveLength = duct.c0 / freq
k = 2 * np.pi / waveLength
qp = 0.01
primSrc = duct.MonopoleSource(position=1,
generator=duct.SineGenerator(qp, freq),
name='Primary source')
L = waveLength * 3 / 4
f = -duct.ro0 * duct.c0 * qp / 2 * np.exp(-1j * k * L)
qs = -qp / 2 * np.exp(-1j * k * L)
secMonoSrc = duct.MonopoleSource(position=1 + L,
generator=duct.SineGenerator(qs, freq),
name='Secondary monopole source')
secDipoleSrc = duct.DipoleSource(position=1 + L,
generator=duct.SineGenerator(
f / (duct.ro0 * duct.c0), freq),
name='Secondary dipole source')
and secondary on the left at x=0.
"""
from __future__ import division
import numpy as np
import duct
duct.xMax = 5
freq = 50
waveLength = duct.c0 / freq
k = 2 * np.pi / waveLength
L = 2
ampPrim = 0.01
sp = duct.MonopoleSource(position=L,
generator=duct.PulseGenerator(ampPrim, 0),
name='Primary source')
# Amplitude and delay to ensure no reflected sound.
# Compared to equation 5.15.4 in Nelson&Elliott we added factor 1/2,
# because in our case the duct is opened on primary source side.
ampSec = -ampPrim / 2
delay = L / duct.c0
ss = duct.MonopoleSource(position=0,
generator=duct.PulseGenerator(ampSec, delay),
name='Secondary source')
duct.animate([sp, ss], reflect=True)