394
CHAPTER 7. LABORATORY WAVE GENERATION
It is important never to lose sight of the fact that even the largest
and most sophisticated laboratory facilities can only be tools to
help with the overall research programs. Laboratory generated
sea states, even when they are able io include all the known
physical parameters, such as wind, currents, temperature differences, etc., will never become replicas in miniature of the real
ocean.” (Ploeg and Funke 1985).
7.6.2
Irregular Wave Synthesis
Several authors have suggested different definitions for categorizing the
techniques for synthesizing irregular waves. And while each set of definitions has its own logic, there has not been total agreement within the
research community on what constitutes “deterministic”, and “nondeterministic” when the terms are applied to irregular wave synthesis. The categorization given below is a combination of the definitions given in Funke
and Mansard (1987) and Huntington (1987), and hopefully, this classification will help the reader understand some of the fundamental differences
between the various techniques.
• Nondeterministic (or probabilistic) irregular wave synthesis assumes the sea surface fluctuations represent a stationary, ergodic process that has a Gaussian distribution
(to first order), and it is assumed the energy distribution
can be characterized with a spectrum (Huntington 1987).
No additional constraints are placed on the method of synthesis, and the time series realizations are nonrep eatable
and can only be known within the bounds of probability.
• PartiaHy Deterministic irregular wave synthesis also assumes the sea surface is Gaussian-distributed and represented by an energy spectrum, but additional constraints
are placed one or more of the random variables (e.g., phasing or spectral amplitudes in exchange for easier synthesis
or a higher degree of control on the time series realizations.
Depending on the particular synthesizing technique, repeatability is possible, thus the time series realizations can
be
• Deterministic irregular wave synthesis assumes a Gauss?an distribution of sea surface dévalions. but also exercises control over specific characteristics of the sea state,
such as wave grouping, wave sequence. wave height maxima. etc The deterministic inegnlar wave svnthesis pro
CHAPTER 7. LABORATORY WAVE GENERATION
It is important never to lose sight of the fact that even the largest
and most sophisticated laboratory facilities can only be tools to
help with the overall research programs. Laboratory generated
sea states, even when they are able io include all the known
physical parameters, such as wind, currents, temperature differences, etc., will never become replicas in miniature of the real
ocean.” (Ploeg and Funke 1985).
7.6.2
Irregular Wave Synthesis
Several authors have suggested different definitions for categorizing the
techniques for synthesizing irregular waves. And while each set of definitions has its own logic, there has not been total agreement within the
research community on what constitutes “deterministic”, and “nondeterministic” when the terms are applied to irregular wave synthesis. The categorization given below is a combination of the definitions given in Funke
and Mansard (1987) and Huntington (1987), and hopefully, this classification will help the reader understand some of the fundamental differences
between the various techniques.
• Nondeterministic (or probabilistic) irregular wave synthesis assumes the sea surface fluctuations represent a stationary, ergodic process that has a Gaussian distribution
(to first order), and it is assumed the energy distribution
can be characterized with a spectrum (Huntington 1987).
No additional constraints are placed on the method of synthesis, and the time series realizations are nonrep eatable
and can only be known within the bounds of probability.
• PartiaHy Deterministic irregular wave synthesis also assumes the sea surface is Gaussian-distributed and represented by an energy spectrum, but additional constraints
are placed one or more of the random variables (e.g., phasing or spectral amplitudes in exchange for easier synthesis
or a higher degree of control on the time series realizations.
Depending on the particular synthesizing technique, repeatability is possible, thus the time series realizations can
be
• Deterministic irregular wave synthesis assumes a Gauss?an distribution of sea surface dévalions. but also exercises control over specific characteristics of the sea state,
such as wave grouping, wave sequence. wave height maxima. etc The deterministic inegnlar wave svnthesis pro