OCEN 201 Introduction to Ocean

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OCEN 201Introduction to Ocean Coastal
Engineering

• Ocean Environment Waves
• Jun Zhang
• Jun-zhang_at_tamu.edu

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General Information

• 71 of the Earth surface is covered by Oceans
• Major Oceans
• 1. Pacific Ocean (46)
• 2. Atlantic Ocean (23)
• 3. Indian Ocean (20)
• 4. Remaining Oceans (11)
• Average Ocean Depth is 3800 m
• Maximum Depth is 11,524 m

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Ocean Floor Reading assignment pp17-19
P18
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• Physical Properties of Ocean Water
• Reading assignment pp19-20
• Primary sea water elements
• Chlorine (55)
• Sodium (30.6)
• Sulfate (7.7)
• Sodium (30.6)
• Magnesium (3.7)
• Potassium (1.1)
• Salinity amount (grams) of dissolved solid
  materials (salts) in grams contained in a
  kilogram seawater (ppt). e.g. Sea Water 35 ppt

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Ocean Currents Reading assignment
pp19-25 Geostrophic Current (pressure gradients
Coriolis force) Ekman Current (Surface wind
friction force Coriolis force)
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• Tides
• Reading assignment pp23-25
• Diurnal tide (once in a tidal day)
• Semi-diurnal tide (twice in a tidal day)
• Mixed tide (tidal day 24.84 hr)
• Tidal day rotation of the Earth with respect to
  the Moon, 24.84 hr

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• Fields Related to Ocean Wave
•      
• Ocean Engineering Ship, water borne
  transport,
• offshore
  structures (fixed and
• floating
  platforms). 
•    
• Navy Military activity, amphibious
  operation,
• WW II Allies landing.
•  
• Coastal Engineering Harbor and ports,
  dredging, coastal
• structures,
• beach erosion, sediment
  transport.
•  

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• Oceanography Ocean environment,
  atmosphere,
• fishing,
  oil spilling, mixing, pollutant
• transport.
•  
•  Environmental Eng. Capping contaminated dredged
• material.
  
• Diffusion
  and dispersion of toxic
• material
  in ocean and costal water.

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Regular and Irregular Waves
Ocean waves are almost always irregular and often
directional (short-crested). Irregular waves can
be viewed as the superposition of a number of
regular waves. Regular waves have the same
frequency, wavelength and amplitude (height).
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T
Time t
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Regular Waves
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Ocean (Irregular) Waves Definitions of
Zero-Upcrossing Downcrossing
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Wave Pattern Combining Four Regular Waves
FFT IFFT (Inverse) Fast Fourier Transform.
Irregular wave Regular Waves
(Frequency Domain Analysis)
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Pierson-Moskowitz Spectrum
JONSWAP Spectrum
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Ocean Wave Spectra P-M JONSWAP Types
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Actual Versus Design Seas
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Wave Pressure and Kinematics

• Linear Wave Theory Simple, good approximation
  for
• 70-80 engineering applications.
• Nonlinear Wave Theory Complicated, necessary for
  about 20-30 engineering applications.
• Both results are based on the assumption of
  non-viscous flow.
• Examples, see animations.

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ENVIRONMENT OVERVIEW

• Picture showing wind, wave, current, and seafloor
  for semisubmersible FPS

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Linear Wave Theory ----- Dispersion Relation
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Using the Dispersion Relation to Find T or L
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Use of Dispersion Relation
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Definition of Deep, Intermediate and Shallow
Water Waves
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Linear Wave Theory ----- Phase velocity
(celerity)
Linear Wave Theory ----- Group (energy)
velocity Wave energy propagates at Cg
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Linear Regular (Periodic) Wave ----- Elevation
Potential
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Linear Regular (Periodic) Wave Energy Density
Average energy per wavelength and per unit width.
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• Nonlinear Wave Theory
• Stokes Expansion
• Hybrid Wave Model
• Boussinesq Equation (shallow water)
• Finite amplitude wave theory

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Web-site for animations
http//cavity.ce.utexas.edu/kinnas/wow/public_html
/waveroom/index.html and Course OCEN 675
http//cavity.ce.utexas.edu/kinnas/wow/public_html
/waveroom/index.html