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They usually occur on the free surface of a water body.

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They are generated due to:
1)Wind action
2)Gravitational pull of sun and moon
3)Catastrophic events

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Wind deflection due to pressure gradient and Coriollis force.

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Gives the type of wind and its velocity.
Ranges from 1 to 17.

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Intensity of cyclone is defined by the distance from its eye to he periphery.
Cyclones caused due to:
1)Temperature difference are called tropical cyclones.
2)pressure difference are called extratropical cyclones.

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Given by various scientists.

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Due to wind system and earth rotation.

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These are the components.

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Fetch is the are of zone over which the wind blows.
Beyond the fetch,the continued waves are called swell waves.(type of spilling breaking)
Surfing is a type of plunging breaking.

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Waves are classified as follows.

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This is wave profile, where:
H - Wave height
T - Wave period

L - Wave length
These 3 are the fundamental components of wave.

η - Wave surface elevation
h - Water depth
a - Wave amplitude
C - Celerity
u,w - water particle orbital velocities in x and z directions.

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VELOCITY POTENTIAL AND DISPERSION EQUATIONS

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VELOCITY POTENTIAL AND DISPERSION EQUATIONS

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We use equations and relations among velocity potential and other parameters for finding out the required characterstics of the wave.
We use the velocity, laplace and bernoulis equation to get the final amplitude formula.
We obtain dispersion relation to have a relation between wavelength,wave period and water depth.
φ - Velocity potential
σ - Wave angular frequency
k - Wave number

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According to d/L ratio,ocean waves are classified.

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The relation between d/L and d/Lo is obtained form the graph.
where Lo - wavelength in deep waters.

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PARTICLE ORBITAL DISPLACEMENT, VELOCITY AND ACCELERATION

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PARTICLE ORBITAL DISPLACEMENT, VELOCITY AND ACCELERATION

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The following expressions give the particle orbital displacement,velocity and accelerations for the given progressive sine wave.
where,
D - Semi major axis
B - Semi minor axis

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For shallow waters,the particles take elliptical shape.
For deep waters,the particles take circular shape.

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When group of waves travel, the velocity of the group is not the direct superimposition of velocities of individual waves.
This group velocity is called group celerity.
CG - Group celerity

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When waves are in motion, the particles upon completion of each nearly an elliptical or circular motion would have advanced a short distance in the direction of propagation.
Consequently there is a mass transport in the direction of progress of the wave.
The mass transport velocity at any depth z below S.W.L is given.

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When a crest line approches the coast it will slowly be changing its angle parallel to the shore.
This process is called wave refraction.
Diffraction is the process that occurs when the moving water encounters a break water.
The diffracted water will move into the shadow region from the light region.
The water which directly hits the breakwater reflects back.

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Total energy is sum of potential and kinetic energy

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They are classified as:
1)Small amplitude waves - Airy's wave theory
2)Finite amplitude waves :
- Stokes theory : d/L > 0.1
- Cnoidal theory: d/L € (0.02,0.1)
- Solitary theory: d/L < 0.02
Waves are classified according to this dimensionless number.
Solitary waves are no periodic with no definite wavelength.

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Loads on off-shore structures can be mainly classified into two categories.
1)Functional loads - all static and dynamic loads during installation.
2)Environmental loads - wind,wave currents,ice etc.
The force regimes are given.

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100 year wave is taken as the design wave for survival condition.
The wave forces on the submerged member are determined using Morison's equation.
This equation is applicable for D/L<0.2 only.
The total force in such case is the sum of particle orbital velocity dependent drag force and particle acceleration dependent inertial force.

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The concept involved is the water particle moving with a velocity carries a momentum.
The value of the total force on cylinder, overturning moment and θmax  are obtained.

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Keulegan and Carpenter studied the forces of sinusoidally oscillating 2 dimensional flow.
They found that CD and CM were smoothly varying functions of a non dimensional parameter called KC number.

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As the waves enters the coastal region, the wave which was symmetric in deep waters becomes unsymmetric and tries to break.
This is called breaking of wave or wave decay.
The limited conditions for the wave to break are given.
1) H/L > 0.142 * tanh(k*d)
2)Wave height greater than 0.178
3)Wave crest angle less than 120o