*WAVWALLOPS

Data format:

A single line with up to 12 values

NWAGEN TETH HS TP HMHS IRAND Tmin Tmax IOSP EXPONENT NB_DIR DELTA

Status :

Optional (dynamics)

Purpose :

To define a WALLOPS spectrum. Used to define more realistic West-African sea states with a WALLOPS spectral distribution (a wind sea peak).

Details :

Parameter	Description
NWAGEN	Number of sinusoidal wave components to be generate
TETH	Direction of propagation (degrees from the positive X axis)
HS	Significant height
TP	Peak period
HMHS	Hmax/Hs ratio (Def = 1.7) If HMHS = 0, no maximum wave height is looked for.
IRAND	Arbitrary positive integer odd number used to trigger the phase random series generation. Two runs using the same IRAND value will generate the same phase series. (Def =12345). A integer I5 is recommended..
Tmin	Minimum period for the waves generation (Default = 0.4*Tp).
Tmax	Maximum period for the waves generation (Default = 2*Tp).
IOSP	= 1 : equal angle between spreading direction = 2 : spreading direction chosen such by constant energy
EXPONENT	Spreading function exponent
NBDIR	number of spreading directions
DELTA	maximum angle in degree of spreading from reference wave direction

Note

1) A Wallops spectrum is given by :

Component	Spectral model
Wind sea peak (WALLOPS type spectrum)	\(S(f) = 0.206625 \frac{H^2_5}{f_p}\Bigl(\frac{f}{f_p}\Bigr)^{-5} e^{-\frac{1}{4}(\frac{f}{f_p})^{-20}}\), \(0.85f_p < f\)

2) The maximum wave height will have just occurred at t = 2.TP + 3(TFIN-2.Tp)/4 (see DYNAMIC for TFIN).

Example :

*WAVWALLOPS
200 180 6 15.5 1.7 12345 3 40

This defines an irregular wave of 200 components, heading towards the negative X-direction. The significant height is 6 m and the peak period is 15.5 seconds. We ask for the ratio of the maximum wave height to the significant height to be 1.7.