Refraction and shoaling analysis Using diffraction graphs ...adac.uaa.alaska.edu/css/images/pdf/online_course/presentation... · Advanced Series on Ocean Engineering: Volume 33, World

$Page 1: Refraction and shoaling analysis Using diffraction graphs ...adac.uaa.alaska.edu/css/images/pdf/online_course/presentation... · Advanced Series on Ocean Engineering: Volume 33, World$
Module 5 – Working with refraction and diffraction

2/9/2016

CE A676 Coastal EngineeringOrson Smith, PE, Ph.D., Instructor 1

Module 5CE A676 Coastal EngineeringOrson P. Smith, PE, Ph.D.Professor Emeritus

Refraction and shoaling analysis

Using diffraction graphs

Case studiesHomer Spit – RCPWAVE analysis

Nikiski – STWAVE analysis


2/9/2016


Consider straight wave crests approaching shallow water at an angle

Part of crest slows before rest

Crest bends in toward shore

Snell’s Law:

Refraction Coefficient:

0

0sinsin

CC

0

0coscos

CC

Kr cos

cos

0 H H K K H

C

Cs rg

0 00 0

2

cos

cos


2/9/2016


Variation of C and at contour of arbitrary orientation (fig. 5.2 & eqn. 5.2‐5.7 in text)

In terms of :

Solve this for each single‐depth cell in grid

1

2

1 Curvature of wave ray depends on gradient of C normal to wave direction: ray bends toward lower C

Lateral transfer of wave energy into a geometric shadow


2/9/2016


Figures in CEM Part II, Ch. 7, after:Goda, Y., 2010. Random Seas and Design of Maritime Structures, 3rd ed., Advanced Series on Ocean Engineering: Volume 33, World Scientific

Smax = 10 (wind waves, i.e., seas); Smax = 75 (swell)

x/L

y/L


2/9/2016


Figures in CEM Part II, Ch. 7, after Goda (2010)B/L = gap‐wavelength ratio

B

period height


period height ratio


2/9/2016





2/9/2016


Rogue River entrance, Oregon

Coos Bay, Oregon

prevailing longshore sediment transport

Ref. Smith et al, 1985 (Waterways Experiment Station report)

Case Study A: 1985


2/9/2016



2/9/2016



2/9/2016


RCPWAVE numerical wave refraction, shoaling, and breaking model• Steady‐state, linear waves – monochromatic• No diffraction – open coast use only

Ref. Smith et al, 1985 (Waterways Experiment Station report)


2/9/2016


Orson Smith, PE, Ph.D.Professor, UAA School of Engineering

Case Study B: 2002‐2003

Alexander Khokhlov, MS Candidate, Dept. of Civil Engineering, UAA School of Engineering

William J. Lee, Research Associate and Ph.D. candidate, Environmental Engineering Program, UAA School of Engineering

Steven Buchanan, RLS, Instructor, Dept. of Geomatics, UAA School of Engineering


2/9/2016


Project Sponsors

Geomega, Inc. (Boulder, CO)

Chevron Environmental Management Company (San Ramon, CA)

Phase I Scope

Investigate geomorphologic change through history of the site and

survey data measured by UAA

Sample and classify beach materials

Characterize wave climate

Numerical simulations of nearshore wave transformation

Interpret geomorphologic changes with regard to local conditions


2/9/2016


Rigtenders Dock

East Foreland

Mean Mean Spring Tide

North West Range Range Level Station Latitude Longitude (ft) (ft) (ft) Ushagat Island, Barren Islands 58° 57' 152° 16' 11.4 13.7 7.2 SELDOVIA, Kachemak Bay 59° 27' 151° 43' 15.5 18.0 9.4 Homer, Kachemak Bay 59° 38' 151° 27' 15.7 18.1 9.5 Anchor Point 59° 46' 151° 53' 15.9 18.3 9.6 Cape Ninilchik 60° 01' 151° 43' 16.5 19.1 10.1 Ninilchik 60° 03' 151° 40' 16.7 19.1 10.0 Kenai River entrance 60° 33' 151° 17' 17.7 20.7 11.0 Kenai City Pier 60° 33' 151° 14' 17.5 19.8 10.4 Nikiski 60° 41' 151° 24' 17.7 20.5 10.9East Foreland 60° 43' 151° 25' 18.0 21.0 11.2 Sunrise, Turnagain Arm 60° 54' 149° 26' 30.3 33.3 17.1 ANCHORAGE, Knik Arm 61° 14' 149° 53' 25.9 28.8 15.2 North Foreland 61° 03' 151° 10' 18.3 21.0 11.3 Drift River Terminal 60° 34' 152° 08' 15.4 18.1 9.7 Oil Bay, Kamishak Bay 59° 38' 153° 16' 12.6 13.9 7.3


2/9/2016


Composite hourly dataKenai Airport (1973 ‐ 1997)

KPC Terminal, Nikiski (1997 ‐2002)

Radial scale is percent frequency of occurrence

Radial bands indicate 10‐knot wind speed classes acting toward the center

Wind rose analysis software and graphic by Josh Rogers, UAA School of Engineering

WindSpeed

Speedm/sec

Waveparameter

180 deg202.5deg

225 deg

247.5deg

270 deg

292.5deg

315 deg

0-9(5)

knots 2.57

H 0.16 0.17 0.17 0.16 0.14 0.13 0.14

T 1.56 1.77 1.70 1.55 1.43 1.34 1.39

10-19 (15)

knots 7.72

H 0.83 1.53 1.23 0.87 0.68 0.56 0.63

T 3.28 4.56 4.01 3.37 2.98 2.72 2.87

20-29 (25)

knots 12.86

H 1.43 3.19 2.32 1.64 1.28 1.06 1.18

T 4.35 6.43 5.48 4.55 4.01 3.64 3.86

30-39 (35)

knots 18.01

H 1.98 4.87 3.40 1.62

T 5.21 7.90 6.64 4.41

40-49 (45)

knots 23.15

H 2.49 6.56 4.45 2.66

T 5.94 9.16 7.64 5.60

50-59 (55)

knots 28.29

H 2.96 8.25 5.45

T 6.58 10.27 8.52

calculated using CEDAS – ACES wave prediction software ( Veri‐Tech, Inc.)


2/9/2016


Extreme Waves Offshore of the Mouth of the Kenai River, 1973 - 2000

00.10.20.30.40.50.60.70.80.9

1

0 5 10 15 20 25 30

Wave Height, H' (ft)

Pro

bab

ilit

y o

f H

<H

'

Estimated Function

Data, 1973 - 2000

Extremal wave analysis by Heike Merkel from previous study sponsored by PN&D, Inc., and City of Kenai

Beach ice grows in upper tidelands and floats free to form sediment‐laden conglomerates

Average ice conditions 1‐15 February, showing color codes of concentration from 0 (no ice) to 10 tenths (100% ice cover) and hatch patterns to indicate stage of development (from Cook Inlet Ice Atlas by CRREL and UAA for NOAA, 2000)


2/9/2016


Samples collected by Alexander Khokhlov

Analysis by Curtis Townsend, UAA Civil Engineering student

Sample No. 3, 4, 6, & 7

0

20

40

60

80

100

0.010.1110100

Grain Size , mm

Pe

rce

nt

Fin

er

#4: substrate below #3

#3: surface just north ofdock

#6: surface, just south ofopen-cell wall

#7: surface 40 ft offsouthern open-cell wall


2/9/2016


#

#

#

#

#

#

##

#

#

#

110

100

90

80

70

60

50

4030 20 10

MLLW

13

12

11

10

9

7

6

5

3, 41, 2

8

586800

586800

587000

587000

587200

587200

587400

587400

587600

5876006728

600

672

8600

6728

800

6728

800

672

9000

6729000

672

9200

67292

00

672

940

0 6729400

672

9600

6729600

6729

800

672

9800

N

UTM Zone 5 (Meters)NAD 83

300 0 300

Feet

100 0 100

Meters

•Topographic survey: Steve Buchanan, RLS, Heike Merkel, Alissa Pempek, Josh Rogers, Alexander Khokhlov

•Hydrographic survey: Bill Lee, Alexander Khokhlov, Orson Smith

Low tide view of North inshore corner of Rigtenders Dock, July 2002.


2/9/2016


Grid developed by Alexander Khokhlov and Bill Lee from NOAA archives and UAA 2002 survey data for STWAVE simulations

Steady‐state linear waves

Evolution of directional spectrumMultiple waves of different H, T, and Non‐linear transfer of energy within spectrum

Bottom friction, percolation, wind‐input, simple current interaction, breaking

Diffraction past simple structures


2/9/2016


STWAVE output for Hs = 5.45 m, Tp = 9.09 sec, direction = 225° T (from southwest). Arrows are wave rays, contours are wave height, and colors are depths at mean tide level.

Climatic average condition: H = 0.6 m (2 ft), T = 4.2 sec, direction = 24 Northward

Beach barrier (Rigtenders Dock) blocks longshore transport from South


2/9/2016


Offshore margin of Rigtenders Dock at low tide.


2/9/2016


Phase II Scope

Extended numerical simulations

2nd topographic & hydrographic surveyQuantitative analysis of annual change

Wave measurementsEvaluation assumptions based on hindcast wave climatology

Discuss alternative engineering responses to erosion

Example BMAP analysis of profile change and of beach fill configurations

Example BMAP analysis of profile change and of beach fill configurations


2/9/2016


Not For Navigational Use

Not Fo

N

EW

S

58°46'

58°52'

58°58'59°2'59°6'59°10'

59°16'

59°22'

59°28'

59°34'

59°40'

59°46'

59°52'

59°58'60°2'60°6'60°10'

60°16'

60°22'

60°28'

60°34'

60°40'

60°46'

60°52'

60°58'6

1°2'61°6'61°10'

61°16'

61°22'

154°48'

154°48'

154°36'

154°36'

154°24'

154°24'

154°12'

154°12'

154°00'

154°00'

153°48'

153°48'

153°36'

153°36'

153°24'

153°24'

153°12'

153°12'

153°00'

153°00'

152°48'

152°48'

152°36'

152°36'

152°24'

152°24'

152°12'

152°12'

152°00'

152°00'

151°48'

151°48'

151°36'

151°36'

151°24'

151°24'

151°12'

151°12'

151°00'

151°00'

150°48'

150°48'

15

15

Grid development by Alexander Khokhlov and Bill Lee, UAA/SOE

NOAA Chart 16660

NOAA Chart 16640


2/9/2016



2/9/2016



2/9/2016


Seawall


2/9/2016


Data collected from 2003/06/09 13:36:40 to 2003/07/18 11:36:39

468 sea state measurements, 8.41 MB

Sample rate = 2 Hz, burst length = 1,024 seconds (2048 samples) every 2 hours

Spectral analysis:Frequency minimum = 0.04 Hz,

Ensemble average every 128 samples

Hanning‐type smoothing of ensembles

Wave height (from ADP data) and Wind speed (from NOAA database)Nikiski (06/09/2003 - 07/18/2003)

0

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

Date

6/10

/2003

6/11

/2003

6/12

/2003

6/13

/2003

6/14

/2003

6/14

/2003

6/15

/2003

6/16

/2003

6/17

/2003

6/18

/2003

6/19

/2003

6/20

/2003

6/21

/2003

6/22

/2003

6/23

/2003

6/24

/2003

6/25

/2003

6/25

/2003

6/26

/2003

6/27

/2003

6/28

/2003

6/29

/2003

6/30

/2003

7/1/

2003

7/2/

2003

7/3/

2003

7/4/

2003

7/5/

2003

7/6/

2003

7/6/

2003

7/7/

2003

7/8/

2003

7/9/

2003

7/10

/2003

7/11

/2003

7/12

/2003

7/13

/2003

7/14

/2003

7/15

/2003

7/16

/2003

7/17

/2003

7/17

/2003

Date

Win

d s

pee

d (

m/s

)

0

0.5

1

1.5

2

2.5

Wav

e h

eig

ht

(m)

Wind Speed (m/s) Wave Height (m)

Analysis and graph by Alexander Khokhlov, UAA/SOE


2/9/2016


Documents

Refraction and shoaling analysis Using diffraction graphs ...adac.uaa.alaska.edu/css/images/pdf/online_course/presentation... · Advanced Series on Ocean Engineering: Volume 33, World