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Wave Energy Period

Introduction

Flexcom has traditionally modelled wave spectra in terms of either Tz or Tp. If you specify a scatter diagram in terms of Te, Flexcom converts Te into Tz. Cahill and Lewis (2014) state that energy period is related to mean zero up-crossing period as follows:

                                                       (1)

                                       (2)

Separate conversion procedures are used by Flexcom depending on the wave spectrum type.

Pierson-Moskowitz

For Pierson-Moskowitz spectra, γ is equal to 1, so the computation of β and Tz is trivial.  

Jonswap

As discussed in Jonswap Wave, Isherwood (1987) defines wave steepness s as:

                                                       (3)

where g is the gravitational constant. The value of γ is then found from:

       (4)

Flexcom estimates an initial value for Tz, calculates s as per Eq.(3), γ as per Eq.(4), β as per Eq.(2), and finally Tz from Eq.(1). This computation procedure is performed iteratively, until the estimated and computed values of Tz converge.