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Anibal Damiao December 14, 1999 15:05

Sea waves formulas
 
Does anyone knows related sites or information about some formulas that explain the high, measure, talness,... of waves coming to coast in the ocean?

Please respond to my e-mail adress.

Tanks

Anibal Damiao

Patrick Godon December 14, 1999 17:46

Re: Sea waves formulas
 
The long wavelength waves are usually modelled as inertio gravity waves with a shallow water equation and in global ocean circulation currents. THe short wavelength waves that break onto the coast are surface waves that emerge due to a shearing (K-H) instability between the air (wind) and the water (surface of the ocean).

PG

Anibal Damiao December 14, 1999 21:23

Re: Sea waves formulas
 
Do exist a formula like

f(x,y)=abs(x+y)...

do define a smal wave's (in the coast) lenght, curvature, talness?

Anibal damiao


Patrick Godon December 15, 1999 10:57

Re: Sea waves formulas
 
I guess that you are interested in, is when a given wave propagates all the way to the coast where the deepness of the water decreases. In this case the amplitude of the wave increases and its velocity decreases. This effect is well known in tsunami. Tsunami are huge waves produced by an earth-quake in the sea or the impact of a meteorite, etc.. Then a long wavelength wave forms in the sea an propagates towards the coasts. As the deepness of the sea decreases towards the coast, the amplitude of the wave (its tallness if you prefer) increases and its velocity decreases, and its wavelength decreases too. This might explain the relation that you mentioned if y is the tallness of the waves and x is its wavelength (up to a constant factor). This works for small waves too, it just needs to be scaled. It is due to the conservation of energy of the wave and I think that the result can be obtained with a simple 1D Shallow Water Equation, where the thickness of the layer of the water decreases in the direction of the propagating (inertio-gravitational) wave.

You might want to have a look at some books in Geophysics, e.g.:

Pedlosky, J. 1987, "Geophysical Fluid Dynamics", 2nd Edition, New York: Springer.

Patrick

Dr. Ahmad Sana December 15, 1999 17:55

Re: Sea waves formulas
 
I think all the answers to your questions may be found in Shore Protection Manual published by US Army Corps of Engineers. It tells you almost everything about waves in the ocean.

Sana


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