Wave Shoaling Schematic Changes that occur when a wave shoals (moves into shallow water): In deep...
-
Upload
wilfred-hall -
Category
Documents
-
view
223 -
download
2
Transcript of Wave Shoaling Schematic Changes that occur when a wave shoals (moves into shallow water): In deep...
![Page 1: Wave Shoaling Schematic Changes that occur when a wave shoals (moves into shallow water): In deep water = profile of swell is nearly sinusoidal. Enter.](https://reader036.fdocuments.us/reader036/viewer/2022062423/5697bfca1a28abf838ca9793/html5/thumbnails/1.jpg)
Wave Shoaling Schematic
Changes that occur when a wave shoals (moves into shallow water):
In deep water = profile of swell is nearly sinusoidal.
Enter shallow water, waves undergo a systematic transformation.
Wave velocity and wave length decrease while the wave height increases.
Only wave period remains constant.
![Page 2: Wave Shoaling Schematic Changes that occur when a wave shoals (moves into shallow water): In deep water = profile of swell is nearly sinusoidal. Enter.](https://reader036.fdocuments.us/reader036/viewer/2022062423/5697bfca1a28abf838ca9793/html5/thumbnails/2.jpg)
Wave Shoaling – L & C
Deep water - L, C depend only on period
Shallow water - L, C depend only on the water depth
Summarize regions of applications of approximations
Behavior of normalized variables.
![Page 3: Wave Shoaling Schematic Changes that occur when a wave shoals (moves into shallow water): In deep water = profile of swell is nearly sinusoidal. Enter.](https://reader036.fdocuments.us/reader036/viewer/2022062423/5697bfca1a28abf838ca9793/html5/thumbnails/3.jpg)
PinPoutOutside the surf zone
Pin = Pout Wave energy flux is conserved
Ecn = constantEcn = E∞c∞n∞
∞=((1/2n)(C ∞ /C))1/2
Wave Shoaling – H
Explains why orthogonally directed waves increase height during shoaling
Direct compensation for slowing of individual waves and need to maintain constant wave energy flux
Waves convert a significant fraction of their kinetic energy to potential energy
![Page 4: Wave Shoaling Schematic Changes that occur when a wave shoals (moves into shallow water): In deep water = profile of swell is nearly sinusoidal. Enter.](https://reader036.fdocuments.us/reader036/viewer/2022062423/5697bfca1a28abf838ca9793/html5/thumbnails/4.jpg)
Wave Shoaling – Steepness (H/L)
Straightforward consequence of combined shoaling behavior of H & L.
Steepness initially decreases upon entry to intermediate water depth, then rapidly increases until instability condition associated with wave breaking.
![Page 5: Wave Shoaling Schematic Changes that occur when a wave shoals (moves into shallow water): In deep water = profile of swell is nearly sinusoidal. Enter.](https://reader036.fdocuments.us/reader036/viewer/2022062423/5697bfca1a28abf838ca9793/html5/thumbnails/5.jpg)
Wave Refraction Photos
![Page 6: Wave Shoaling Schematic Changes that occur when a wave shoals (moves into shallow water): In deep water = profile of swell is nearly sinusoidal. Enter.](https://reader036.fdocuments.us/reader036/viewer/2022062423/5697bfca1a28abf838ca9793/html5/thumbnails/6.jpg)
Wave Refraction: Wave Crests vs. Wave Rays
Wave crests are the line segments that connect the peaks (or troughs) of a wave field. The crests are visible to the observer.
Wave rays are the lines orthogonal (perpendicular) to the wave crests, which represent the direction of wave propagation
![Page 7: Wave Shoaling Schematic Changes that occur when a wave shoals (moves into shallow water): In deep water = profile of swell is nearly sinusoidal. Enter.](https://reader036.fdocuments.us/reader036/viewer/2022062423/5697bfca1a28abf838ca9793/html5/thumbnails/7.jpg)
Wave Refraction Wave Refraction - Point Reyes
![Page 8: Wave Shoaling Schematic Changes that occur when a wave shoals (moves into shallow water): In deep water = profile of swell is nearly sinusoidal. Enter.](https://reader036.fdocuments.us/reader036/viewer/2022062423/5697bfca1a28abf838ca9793/html5/thumbnails/8.jpg)
c = (gh)1/2
Snell’s Law
)sin()sin(
)sin()sin(
2
2
1
1
∞∞
=
=
αα
αα
cc
cc
Wave Refraction
![Page 9: Wave Shoaling Schematic Changes that occur when a wave shoals (moves into shallow water): In deep water = profile of swell is nearly sinusoidal. Enter.](https://reader036.fdocuments.us/reader036/viewer/2022062423/5697bfca1a28abf838ca9793/html5/thumbnails/9.jpg)
Wave Refraction: Energy flux per unit length of wave crest
Energy flux per unit length of wave crest is not necessarily conserved
Can lead to a decrease in wave height during the shoaling and refraction process.
![Page 10: Wave Shoaling Schematic Changes that occur when a wave shoals (moves into shallow water): In deep water = profile of swell is nearly sinusoidal. Enter.](https://reader036.fdocuments.us/reader036/viewer/2022062423/5697bfca1a28abf838ca9793/html5/thumbnails/10.jpg)
Wave Refraction - La Jolla Canyon
![Page 11: Wave Shoaling Schematic Changes that occur when a wave shoals (moves into shallow water): In deep water = profile of swell is nearly sinusoidal. Enter.](https://reader036.fdocuments.us/reader036/viewer/2022062423/5697bfca1a28abf838ca9793/html5/thumbnails/11.jpg)
2211)()( sEnCsEnC =
2/12/1
2
1⎥⎦⎤
⎢⎣⎡
⎥⎦⎤
⎢⎣⎡=
∞∞∞
ss
cc
nHH
€
Kr =s∞
s
⎡ ⎣ ⎢
⎤ ⎦ ⎥
1/ 2
€
=cos(α ∞)
cos(α )
⎡
⎣ ⎢ ⎤
⎦ ⎥
1/ 2
Combined Refraction and Shoaling
![Page 12: Wave Shoaling Schematic Changes that occur when a wave shoals (moves into shallow water): In deep water = profile of swell is nearly sinusoidal. Enter.](https://reader036.fdocuments.us/reader036/viewer/2022062423/5697bfca1a28abf838ca9793/html5/thumbnails/12.jpg)
Effect of Shoaling
H = 2 mT = 10 sothogonal angle of incidence
![Page 13: Wave Shoaling Schematic Changes that occur when a wave shoals (moves into shallow water): In deep water = profile of swell is nearly sinusoidal. Enter.](https://reader036.fdocuments.us/reader036/viewer/2022062423/5697bfca1a28abf838ca9793/html5/thumbnails/13.jpg)
Effect of Shoaling and Refraction
H = 2 mT = 10 s
compare:orthogonal wave vs. refracting wave
![Page 14: Wave Shoaling Schematic Changes that occur when a wave shoals (moves into shallow water): In deep water = profile of swell is nearly sinusoidal. Enter.](https://reader036.fdocuments.us/reader036/viewer/2022062423/5697bfca1a28abf838ca9793/html5/thumbnails/14.jpg)
Modeling refraction - wave rays
H = 2 mT = 10 sα= 270˚
![Page 15: Wave Shoaling Schematic Changes that occur when a wave shoals (moves into shallow water): In deep water = profile of swell is nearly sinusoidal. Enter.](https://reader036.fdocuments.us/reader036/viewer/2022062423/5697bfca1a28abf838ca9793/html5/thumbnails/15.jpg)
Modeling refraction - wave rays - double period
H = 2 mT = 20 sα= 270˚
![Page 16: Wave Shoaling Schematic Changes that occur when a wave shoals (moves into shallow water): In deep water = profile of swell is nearly sinusoidal. Enter.](https://reader036.fdocuments.us/reader036/viewer/2022062423/5697bfca1a28abf838ca9793/html5/thumbnails/16.jpg)
bathymetry (in feet) focusing waves
“Jaws” Surfing Reef, Maui
Model simulations of individual waves - not time averaged.
![Page 17: Wave Shoaling Schematic Changes that occur when a wave shoals (moves into shallow water): In deep water = profile of swell is nearly sinusoidal. Enter.](https://reader036.fdocuments.us/reader036/viewer/2022062423/5697bfca1a28abf838ca9793/html5/thumbnails/17.jpg)
Wave Diffraction
Lateral translation of energy along a wave crest.
Most noticeable where a barrier interrupts a wave train creating a "shadow zone". Energy leaks along wave crests into the shadow zone.
Also by analogy to light, Huygen's Principle explains the physics of diffraction through a superposition of point sources along the wave crest.
![Page 18: Wave Shoaling Schematic Changes that occur when a wave shoals (moves into shallow water): In deep water = profile of swell is nearly sinusoidal. Enter.](https://reader036.fdocuments.us/reader036/viewer/2022062423/5697bfca1a28abf838ca9793/html5/thumbnails/18.jpg)
Wave Diffraction- Barcelona
![Page 19: Wave Shoaling Schematic Changes that occur when a wave shoals (moves into shallow water): In deep water = profile of swell is nearly sinusoidal. Enter.](https://reader036.fdocuments.us/reader036/viewer/2022062423/5697bfca1a28abf838ca9793/html5/thumbnails/19.jpg)
Modeling with SWANRef/Diff numerical simulation of shoaling and refraction - monochromatic (not spectral - boo.)
SWAN - used here at UF (spectral - yay.)