Pierson-Moskowitz Wave |
 
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Pierson-Moskowitz Wave |
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Pierson and Moskowitz (1964) developed a spectral formulation for a fully developed seastate. The fetch and duration are considered infinitely large (measured data from the North Atlantic was used during the development of the spectral formulation), so that the wind must be of relatively constant speed over a relatively large area for the underlying assumptions to remain valid. The Pierson-Moskowitz spectrum is based on the following formulation:
(1)
where:
•f is the wave frequency in Hertz
•Hs is the significant wave height
•Tz is the mean zero up-crossing period
Flexcom offers a choice of formats for defining a Pierson-Moskowitz wave spectrum. The standard or default option is in terms of significant wave height Hs and mean zero up-crossing period Tz as per the Equation above. Alternatively, you can define the spectrum in terms of Hs and Tp, where Tp is the spectrum peak period. In this case, Tp is converted internally to Tz using the relationship:
•*WAVE-PIERSON-MOSKOWITZ is used to specify a Pierson-Moskowitz random sea wave spectrum or spectra.
If you would like to see an example of how this keyword is used in practice, refer to B01 - Steel Catenary Riser.