ENERGY DISTRIBUTION CURVES OF DEVELOPING AND FULLY ARISEN SEAS

The Pierson-Moskowitz (PM) ocean wave spectrum, derived from analyses of many ocean wave records, contains two constants for fully arisen sea conditions. This frequency spectrum can be converted to a period base, termed an energy distribution curve (EDC), with apex increasing with the steady wind velocity. A unique relationship results between the significant wave height and T (sub max). A new dimensionless form of the PM spectrum and EDC is presented which incorporates wave age (c/u). The triangular form of the latter permits the definition of working upper (T sub u) and lower (T sub L) period limits of the many wave trains present. Using a recently derived growth relationship for waves in a developing sea, the vibrations of the constants in the spectral equation of the fully arisen sea are determined. Knowing the fetch of the fully arisen sea, values of the aforementioned constants have been related to the ratio F/F sub FAS for fetch controlled conditions. Substitution of these back into the spectrum of EDC equations exhibits the growth pattern of the developing sea. The minimum fetch (F sub FAS) for the fully arisen sea has been related to the steady wind velocity. It has also been connected to the minimum duration (t sub FAS), by using a mean group velocity of the progressively enlarging T (sub max) trains, to any specified point in the fetch. In this way values of t/t sub FAS, and hence, to corresponding values of the aforementioned constants. Conclusions based on this study are categorized with regard to fully arisen sea and developing seas.

• Supplemental Notes:
  • Abstract prepared by Texas A&M University.
• Corporate Authors:

  International Association for Hydraulic Research

  Room 61, Box 177
  Delft,   Netherlands 
• Authors:
  • Silvester, R
  • Vongvusessomjai, S
• Publication Date: 1970-4

Media Info

• Features: References;
• Pagination: p. 493-521
• Serial:
  • Journal of Hydraulic Research
  • Volume: 8
  • Issue Number: 4
  • Publisher: International Association for Hydraulic Research

Subject/Index Terms

• TRT Terms: Electromagnetic spectrum; Hydrodynamics; Wave motion
• Old TRIS Terms: Wave force analysis
• Subject Areas: Design; Hydraulics and Hydrology; Marine Transportation;

Filing Info

• Accession Number: 00050936
• Record Type: Publication
• Source Agency: National Maritime Research Center, Galveston
• Files: TRIS
• Created Date: Jan 31 1974 12:00AM