1 / 33

Wave Modeling

Wave Modeling. Local Wave Transformations Billy L. Edge & Margery Overton CVEN 695-02. Bathymetric Data. Why do we need wave models?. Wave climate assessment at the project site is important to most coastal & ocean engineering projects, including - navigation and channel studies

rcooper
Download Presentation

Wave Modeling

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Wave Modeling Local Wave Transformations Billy L. Edge & Margery Overton CVEN 695-02

  2. Bathymetric Data

  3. Why do we need wave models? • Wave climate assessment at the project site is important to most coastal & ocean engineering projects, including - navigation and channel studies - on/offloading of ships - optimization of harbor layouts - design of structures (breakwaters, etc.) • shoreline erosion projects, etc. • Nearshore wave conditions are normally determined from deepwater conditions - long-term nearshorewave data are usually unavailable - transform offshore wave data to nearshore (wind-generation, shoaling, refraction, breaking, dissipation, bottom friction) – regional scale models - investigate local scale phenomena (refraction, wave reflection, diffraction, nonlinear wave-wave and wave-current interaction) –local scale models

  4. Regional Scale Wave Modeling • Scale O(100 km~5000 km) • Spectral wind-wave models (WAM) • Scale O(10 km ~100 km) • Spectral wind-wave models (STWAVE and SWAN) • Dominant process: wind input, shoaling and refraction • Wave action: conservation equation • Assume phase-averaged wave properties vary slowly over distances of the order of a wavelength • Cannot accurately resolve rapid variations that occur at sub-wavelength scale due to wave reflection/diffraction

  5. Local Scale Wave Modeling • Scale O(1 km ~ 10 km) • Elliptic mild-slope model (CGWAVE) • Parabolic mild-slope model (REFDIF) • Boussinesq wave model (BOUSS-2D) • Dominant processes: shoaling, refraction, breaking, reflection, diffraction, wave nonlinearities due to interactions of different frequencies and ambient currents and structures • All models use vertically integrated eqns for wave propagation in 2D horizontal plane • CGWAVE assumes hyperbolic cosine variation of the velocity potential over depth, and BOUSS-2D assumes a quadratic variation

  6. STWAVE CGWAVE/ REFDIF BOUSS Shoaling/Refraction    Wave Breaking    Wave-Current Interaction    Nonlinear Interactions   Diffraction/Reflection   Phase averaging Phase averaging Phase resolving Summary of Model Features

  7. Spectral Wind-Wave Models • Advantages • wind-wave generation • shoaling, refraction, breaking • wave-current interaction • applicable to large domains (deep to shallow water) • Disadvantages • reflection, diffraction • steady-state

  8. Elliptic Mild-Slope Models • Advantages • well suited for long-period oscillations • shoaling, refraction, breaking, bottom friction • reflection, diffraction • wave-current interaction (in future version) • flexibility of finite elements • Disadvantages • nonlinear interactions in shallow water (in future version)

  9. Parabolic Mild-Slope Models • Advantages • shoaling, refraction, breaking, bottom friction • Refraction, reflection, diffraction • wave-current interaction • Disadvantages • Grid limitations in size and regular gridding

  10. Boussinesq Wave Models • Advantages • shoaling, refraction, breaking, bottom friction • reflection, diffraction, nonlinear interactions • wave-induced currents, wave-current interaction • Disadvantages • computationally intensive • 2-D very computationally intensive

  11. Applicability • STWAVE: • ideal for wave propagation in open water • SWAN: • time dependent, larger domain • Mild-Slope: • ideal for long-period oscillations in harbors (CGWAVE) • suited for strong diffraction & reflection • more flexibility with finite element method(CGWAVE) • rapid solutions(REFDIF) • BOUSS-2D: • ideal for wave transformation near entrance channels and harbors • nonlinear interactions in shallow water • wave-induced currents near structures and surfzone

  12. Engineering Practice - 1 • CORPS wave models have good physics to provide reliable estimates to projects • Integrated with tools (SMS,etc.) • Used in support of a variety of research and engineering studies • Have strengths & weaknesses – no one model can do it all! • Validated with field/lab data & checked against analytical solutions • MIKE21 wave models … • DELFT3D wave models …

  13. STWAVE • Wind forcing • Current forcing • Wave-current • Regional modeling • Deepwater wave transformation up to pre-breaking depths • Finite difference • Spectral, steady state • Quick to run • Good front end STWAVE computed wave Heights

  14. CGWAVE • Diffraction • Reflection • Refraction • Breaking • Bottom friction • Entrance losses • Finite element mesh • Spectral sea state • Wave-current Interaction (in testing) • Wave-wave Interaction (in testing) • No wind Input CGWAVE Sea state for Morro Bay, CA

  15. BOUSS-2D • Time-dependent • Open coast, harbor and surf zone waves • Shoaling, refraction, reflection, diffraction, dissipation and run-up • Finite difference • Random spectral sea state modeling • Wave-induced currents • Nonlinear waves, sub- and super-harmonics BOUSS-2D Simulation for Everglades project

  16. Engineering Practice -3 • Have to use models if no nearshore field data available • Using models that are in common practice and have acceptance in the engineering community is preferred to one of a kind models • Project-specific problems must determine the type of model for a study • Detailed model documentation is necessary

  17. Grays Harbor, Washington

  18. Grays Harbor, Washington

  19. Entrained Sand

  20. Regions of Application of Wave Models

  21. Solitary/CnoidalWaves

  22. Wave Prediction (Deep Water)

  23. Combined Refraction and Shoaling(Dean and Dalrymple)

  24. Random Waves • Analysis Methods • Eye • ZUC • ZDC • Spectral

  25. Random Wave Spectra JONSWAP

  26. Wave Spectra JONSWAP TMA Pierson Moskowitz Other

  27. Mild Slope Equation http://www.coastal.udel.edu/refdif/img20.htm

  28. CONCLUSIONS • BOUSS-2D is a powerful nonlinear model for estimating waves in shallow and intermediate water depths where wave diffraction and nonlinearities are important • Model is ready for project applications • SMS interface of BOUSS-2D • MAKE THINGS AS SIMPLE AS POSSIBLE BUT NO SIMPLER!!! – “Albert Einstein”

  29. REFDIF

More Related