Ochi Hubble Wave Spectrum

How to use/model Ochi Hubble wave spectrum in MOSES. Is it possible?

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  • Hi Rahul,

    Based on my understanding, the input spectra will be based on 1m Hs. Correct? But for ochi-hubble spectra got two different spectrum combined together i.e. wind sea and swell. So we have two different set of Hs, Gamma, fp, for wind sea and swell. Gamma and peak freq, fp already calculated as part of the input spectra. How about the Hs? 

  • Hi Mohd,
    When inputting a spectrum using the "&data curve f_spectrum/p_spectrum" command, it is necessary to define the Hs (significant wave height) of the entire spectrum. This allows MOSES to scale the spectrum such that the area under the curve equals Hs**2/16.
    If you are using the Ochi formulation, you can find instructions on obtaining Hs for dual-peak spectra in his paper. Assuming that both the low and high-frequency component spectra are narrow-banded, and their sum (the entire spectrum) is also narrow-banded, the following simple relationship holds:
    Hs = sqrt(Hs1**2 + Hs2**2)
    Here, Hs represents the significant wave height of the entire spectrum, Hs1 represents the significant wave height of the low-frequency component, and Hs2 represents the significant wave height of the high-frequency component.
    If the component spectra are not narrow-banded, you can find the derivation for significant wave height in Appendix A of the same paper.
    When using an input spectrum (user-defined) in MOSES, you do not need to define the period. I have attached a document we prepared addressing some user questions related to spectra, which will provide a better understanding of user-defined spectra and important considerations.
    Please feel free to reach out if you have any further questions.
    Regards,
    Rahul

    PDF

    Answer Verified By: Mohd Ariff Md Malik 

  • Hi Rahul

    Thanks for the explanation. Its really helpful.