1. OCEN 201 Introduction to Ocean & Coastal Engineering Ocean Environment &Waves Jun Zhang Jun-zhang@tamu.edu

2. 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

3. Ocean Floor Reading assignment pp17-19 P18

4. Physical Properties of Ocean Water Reading assignment pp19-20 Primary sea water elements 1.Chlorine (55%) 2.Sodium (30.6) 3.Sulfate (7.7%) 4.Sodium (30.6) 5.Magnesium (3.7%) 6.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

5. Ocean Currents Reading assignment pp19-25 Geostrophic Current (pressure gradients & Coriolis force) Ekman Current (Surface wind friction force & Coriolis force)

6. Tides Reading assignment pp23-25 1.Diurnal tide (once in a tidal day) 2.Semi-diurnal tide (twice in a tidal day) 3.Mixed tide (tidal day 24.84 hr) Tidal day: rotation of the Earth with respect to the Moon, ~24.84 hr

7. 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.

8. 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.

9. 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).

10. T Time t

11. Regular Waves

12. Ocean (Irregular) Waves Definitions of Zero-Upcrossing & Downcrossing

13. Wave Pattern Combining Four Regular Waves FFT & IFFT – (Inverse) Fast Fourier Transform. Irregular wave Regular Waves (Frequency Domain Analysis)

14. Pierson-Moskowitz Spectrum JONSWAP Spectrum

15. Ocean Wave Spectra: P-M & JONSWAP Types

16. Actual Versus Design Seas

18. 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.

19. ENVIRONMENT OVERVIEW Picture showing wind, wave, current, and seafloor for semisubmersible FPS

20. Linear Wave Theory ----- Dispersion Relation

21. Using the Dispersion Relation to Find T or L

22. Use of Dispersion Relation

23. Definition of Deep, Intermediate and Shallow Water Waves

24. Linear Wave Theory ----- Phase velocity (celerity) Linear Wave Theory ----- Group (energy) velocity Wave energy propagates at C g

25. Linear Regular (Periodic) Wave ----- Elevation & Potential

26. Linear Regular (Periodic) Wave Energy Density: Average energy per wavelength and per unit width.

27. Nonlinear Wave Theory Stokes Expansion Hybrid Wave Model Boussinesq Equation (shallow water) Finite amplitude wave theory

28. Web-site for animations http://cavity.ce.utexas.edu/kinnas/wow/public_html/wavero om/index.html and Course OCEN 675 http://cavity.ce.utexas.edu/kinnas/wow/public_html/waver oom/index.html