D

Word -> "Mot"	Symbol	Unity	Definition
Deep-water wave -> "Vagues en eau profonde"			Waves whose wavelength is smaller than twice the depth of the water it is travelling in.
Deep-water wavelength -> "Longueur d'onde en eau profonde"		m	"Wavelength" where waves are not affected by the bottom, i.e. obey the equation 2=g.k.
Diffraction -> "Diffraction"			The phenomenon by which waves spread in presence of obstacles and strong currents. See also "Huyghens principle".
Directional spectral density function -> "Fonction directionnelle de densité spectrale"			Representation of the distribution of the wave energy with both frequency and direction.So that the contribution to energy of each component of the wave coming from a given direction can be known. See also "Spectral density function".
Direction of wave propagation -> "Direction de propagation"		deg	See "Mean wave direction", "Peak direction".
Dispersion -> "Dispersion"			Phenomenon due to the fact that waves of different frequencies propagate with different celerities.
Dispersion relationship -> "Relation de dispersion"			-> see form
Dispersive waves -> "Ondes dispersives"			Ocean waves are dispersive which means that the "Phase velocity" increases with the "Wavelength". It results that energy, which speed is the "Group velocity", travels slower than the wave crest.