Sediment Properties and the Acoustic Field in a Three-layer Waveguide David Barclay AOS seminar June...
-
Upload
garey-harmon -
Category
Documents
-
view
216 -
download
3
Transcript of Sediment Properties and the Acoustic Field in a Three-layer Waveguide David Barclay AOS seminar June...
![Page 1: Sediment Properties and the Acoustic Field in a Three-layer Waveguide David Barclay AOS seminar June 1st, 2006.](https://reader036.fdocuments.us/reader036/viewer/2022062805/5697c0131a28abf838cccf27/html5/thumbnails/1.jpg)
Sediment Properties and the Acoustic Field in a Three-layer Waveguide
David Barclay
AOS seminar
June 1st, 2006
![Page 2: Sediment Properties and the Acoustic Field in a Three-layer Waveguide David Barclay AOS seminar June 1st, 2006.](https://reader036.fdocuments.us/reader036/viewer/2022062805/5697c0131a28abf838cccf27/html5/thumbnails/2.jpg)
Overview
• Motivation
• Acoustic field in a three layer wave guide
• The Makai experiment
• Data and model comparison
• Sediment properties
![Page 3: Sediment Properties and the Acoustic Field in a Three-layer Waveguide David Barclay AOS seminar June 1st, 2006.](https://reader036.fdocuments.us/reader036/viewer/2022062805/5697c0131a28abf838cccf27/html5/thumbnails/3.jpg)
A simple thought experiment…
V
€
f (θ) =fo
1−V
ccos(θ)
€
θ
€
Δf = f (0) − f (π ) ≈2Vfo
c
Sound speed in the medium can then be found:
Furthermore:
€
cosθ1
c1
=cosθ2
c2
![Page 4: Sediment Properties and the Acoustic Field in a Three-layer Waveguide David Barclay AOS seminar June 1st, 2006.](https://reader036.fdocuments.us/reader036/viewer/2022062805/5697c0131a28abf838cccf27/html5/thumbnails/4.jpg)
A three layer wave guide witha moving source
€
∇2φ1 −1
c12
∂ 2φ1
∂t 2= −Qδ(x − x '−Vt)δ(y)δ(z − z')e iΩt
€
∇2φ2 −1
c22
∂ 2φ2
∂t 2= 0
€
∇2φ3 −1
c32
∂ 2φ3
∂t 2= 0
x
y
z
hydrophonesea bed
seasurface
bender
microphone
hydrophonevertical array
Z’
h
c - Sediment
c - Ocean
c - Air
BCs ii jj and i’j’
![Page 5: Sediment Properties and the Acoustic Field in a Three-layer Waveguide David Barclay AOS seminar June 1st, 2006.](https://reader036.fdocuments.us/reader036/viewer/2022062805/5697c0131a28abf838cccf27/html5/thumbnails/5.jpg)
A few transforms and manipulationslater…
€
φ1(x,z, t) =Qe iΩt
16π 3ie ip(x−x '−Vt )e isyF1(η1,η 2,η 3)dpds
−∞
∞
∫−∞
∞
∫
€
φ2(x,z, t) =Qb12e
iΩt
8π 3ie ip(x−x '−Vt )e isyF2(η1,η 2,η 3)dpds
−∞
∞
∫−∞
∞
∫
€
φ3(x,z, t) =Qb13e
iΩt
8π 3ie ip(x−x '−Vt )e isyF3(η1,η 2,η 3)dpds
−∞
∞
∫−∞
∞
∫
€
ηi = η i(c i, p,s)where
€
bij =ρ i
ρ j
![Page 6: Sediment Properties and the Acoustic Field in a Three-layer Waveguide David Barclay AOS seminar June 1st, 2006.](https://reader036.fdocuments.us/reader036/viewer/2022062805/5697c0131a28abf838cccf27/html5/thumbnails/6.jpg)
Evaluating the integral
• Avoid poles in F2 (located in II and IV quadrants) using a hyperbolic tangent contour.
€
φ2(x,z, t) =Qb12e
iΩt
16π 3ie ip(x−x '−Vt )e isyF2(η1,η 2,η 3)dpds
−∞
∞
∫−∞
∞
∫
Locate receiver at (0, 0, h).
- p’
+ p’
complex p plane
![Page 7: Sediment Properties and the Acoustic Field in a Three-layer Waveguide David Barclay AOS seminar June 1st, 2006.](https://reader036.fdocuments.us/reader036/viewer/2022062805/5697c0131a28abf838cccf27/html5/thumbnails/7.jpg)
Evaluating the integral
• Avoid poles in F2 (located in II and IV quadrants) using a hyperbolic tangent contour.
€
φ2(x,z, t) =Qb12e
iΩt
16π 3ie ip(x−x '−Vt )e isyF2(η1,η 2,η 3)dpds
−∞
∞
∫−∞
∞
∫
Locate receiver at (0, 0, h).
- p’
+ p’
complex p plane
![Page 8: Sediment Properties and the Acoustic Field in a Three-layer Waveguide David Barclay AOS seminar June 1st, 2006.](https://reader036.fdocuments.us/reader036/viewer/2022062805/5697c0131a28abf838cccf27/html5/thumbnails/8.jpg)
The Makai Experiment
![Page 9: Sediment Properties and the Acoustic Field in a Three-layer Waveguide David Barclay AOS seminar June 1st, 2006.](https://reader036.fdocuments.us/reader036/viewer/2022062805/5697c0131a28abf838cccf27/html5/thumbnails/9.jpg)
Locations of SIO’s Fly-By arrayin the MAKAI experiment
SIO shallow site a) array horizontal, anchored on sea bed parallel to shoreline SIGNALS RECORDED
i) Aircraft overflights (50 Hz to 5 kHz) ii) Ambient noise (50 Hz to 5 kHz) b) array vertical, free drifting SIGNALS RECORDED
i) Aircraft overflights (50 Hz to 5 kHz) ii) Ambient noise (50 Hz to 5 kHz)
R/V Kilo Moana site a) array vertical, free drifting SIGNALS RECORDED
i) Aircraft overflights (50 Hz to 5 kHz) ii) Broadband ambient noise (50 Hz to 50 kHz) iii) Comms signals from R/V Kilo Moana
R/V Kilo Moana(water depth ≈ 100m)
SIO shallow site(water depth ≈ 15m)
![Page 10: Sediment Properties and the Acoustic Field in a Three-layer Waveguide David Barclay AOS seminar June 1st, 2006.](https://reader036.fdocuments.us/reader036/viewer/2022062805/5697c0131a28abf838cccf27/html5/thumbnails/10.jpg)
The Flyby Array
ITC6050C
Tilt/compasssensor
100 lbs maxweight
12 m
0.325 m
11 elements
16 Ch. Data Acquisition
High Bandwidth (> 50 kHz)
Photo by Paul Roberts
![Page 11: Sediment Properties and the Acoustic Field in a Three-layer Waveguide David Barclay AOS seminar June 1st, 2006.](https://reader036.fdocuments.us/reader036/viewer/2022062805/5697c0131a28abf838cccf27/html5/thumbnails/11.jpg)
RF capability
![Page 12: Sediment Properties and the Acoustic Field in a Three-layer Waveguide David Barclay AOS seminar June 1st, 2006.](https://reader036.fdocuments.us/reader036/viewer/2022062805/5697c0131a28abf838cccf27/html5/thumbnails/12.jpg)
Putting the array on the bottom
![Page 13: Sediment Properties and the Acoustic Field in a Three-layer Waveguide David Barclay AOS seminar June 1st, 2006.](https://reader036.fdocuments.us/reader036/viewer/2022062805/5697c0131a28abf838cccf27/html5/thumbnails/13.jpg)
Other parameters and instruments
V, z’, h, c1, c2, 1, 2, 3
Aeroplane Track
Dis
tan
ce to
b
ouy
(m
)A
ltitu
de
(ft)
Airs
pe
ed
(m
/s)
![Page 14: Sediment Properties and the Acoustic Field in a Three-layer Waveguide David Barclay AOS seminar June 1st, 2006.](https://reader036.fdocuments.us/reader036/viewer/2022062805/5697c0131a28abf838cccf27/html5/thumbnails/14.jpg)
Aircraft
Maule MXT7-180 STO
![Page 15: Sediment Properties and the Acoustic Field in a Three-layer Waveguide David Barclay AOS seminar June 1st, 2006.](https://reader036.fdocuments.us/reader036/viewer/2022062805/5697c0131a28abf838cccf27/html5/thumbnails/15.jpg)
Dataand
Model Comparison
![Page 16: Sediment Properties and the Acoustic Field in a Three-layer Waveguide David Barclay AOS seminar June 1st, 2006.](https://reader036.fdocuments.us/reader036/viewer/2022062805/5697c0131a28abf838cccf27/html5/thumbnails/16.jpg)
Spectrogram Comparison
Model Data
Colour bars [Pa]
![Page 17: Sediment Properties and the Acoustic Field in a Three-layer Waveguide David Barclay AOS seminar June 1st, 2006.](https://reader036.fdocuments.us/reader036/viewer/2022062805/5697c0131a28abf838cccf27/html5/thumbnails/17.jpg)
Pressure time series comparison
![Page 18: Sediment Properties and the Acoustic Field in a Three-layer Waveguide David Barclay AOS seminar June 1st, 2006.](https://reader036.fdocuments.us/reader036/viewer/2022062805/5697c0131a28abf838cccf27/html5/thumbnails/18.jpg)
Data and Model Spectra comparison
Departure frequency
Approach frequency
![Page 19: Sediment Properties and the Acoustic Field in a Three-layer Waveguide David Barclay AOS seminar June 1st, 2006.](https://reader036.fdocuments.us/reader036/viewer/2022062805/5697c0131a28abf838cccf27/html5/thumbnails/19.jpg)
Model optimization
Ratio of amplitudes vs. Peak location
c = 1640 m/s c = 1519 m/s
![Page 20: Sediment Properties and the Acoustic Field in a Three-layer Waveguide David Barclay AOS seminar June 1st, 2006.](https://reader036.fdocuments.us/reader036/viewer/2022062805/5697c0131a28abf838cccf27/html5/thumbnails/20.jpg)
RMS of measured ratios of amplitudes - modeled
c = 1519 m/s
![Page 21: Sediment Properties and the Acoustic Field in a Three-layer Waveguide David Barclay AOS seminar June 1st, 2006.](https://reader036.fdocuments.us/reader036/viewer/2022062805/5697c0131a28abf838cccf27/html5/thumbnails/21.jpg)
SedimentProperties
![Page 22: Sediment Properties and the Acoustic Field in a Three-layer Waveguide David Barclay AOS seminar June 1st, 2006.](https://reader036.fdocuments.us/reader036/viewer/2022062805/5697c0131a28abf838cccf27/html5/thumbnails/22.jpg)
Sediment Properties• Wet density = 1685 kg/m3
• Grain density = 2407 kg/m3
• Sound Speed ~ 1540 m/s
Data by Hamilton (o), Richardson and Briggs (x) and curve according to Buckingham
![Page 23: Sediment Properties and the Acoustic Field in a Three-layer Waveguide David Barclay AOS seminar June 1st, 2006.](https://reader036.fdocuments.us/reader036/viewer/2022062805/5697c0131a28abf838cccf27/html5/thumbnails/23.jpg)
Physical grain parameters
Mean effective radius
Perimeter
RMS roughness
Major/minor axis
Original image
Image w/ background removed
Processed Image
What description of size and shape relates to intergranular friction?
Validity of grains as spheres?
![Page 24: Sediment Properties and the Acoustic Field in a Three-layer Waveguide David Barclay AOS seminar June 1st, 2006.](https://reader036.fdocuments.us/reader036/viewer/2022062805/5697c0131a28abf838cccf27/html5/thumbnails/24.jpg)
Fourier Roughness
€
R = ro + α n sin(nθ)
n=1
n=2
n=3
![Page 25: Sediment Properties and the Acoustic Field in a Three-layer Waveguide David Barclay AOS seminar June 1st, 2006.](https://reader036.fdocuments.us/reader036/viewer/2022062805/5697c0131a28abf838cccf27/html5/thumbnails/25.jpg)
Thank you:
Prof. Mike Buckingham
Fernando Simonet
Eric Giddens
Paul Roberts
Yuri Platoshyn
![Page 26: Sediment Properties and the Acoustic Field in a Three-layer Waveguide David Barclay AOS seminar June 1st, 2006.](https://reader036.fdocuments.us/reader036/viewer/2022062805/5697c0131a28abf838cccf27/html5/thumbnails/26.jpg)
Sediment Properties and the Acoustic Field in a Three-layer Waveguide
David Barclay
AOS seminar
June 1st, 2006