Linear wave theory Flashcards
1
Q
Types of coast - Soft
A
- influenced by natural processes
- change at various timescales
2
Q
Types of coasts - hard
A
- resist natural forces
- change mostly at very long term timescales
3
Q
What influences coastal behaviour?
A
-geological controls (bedrock, natural features…)
- natural forcing (waves, tides, rivers…)
- interaction between different parts of a coastal system
- human intervention
4
Q
World wave mean height map
A
- large waves found in vast oceans
- waves small closer to land
5
Q
Water wave generation
A
- resulant of wind shear stress acting on the sea surface
- size dependant on; wind speed and direction
6
Q
two wave categories
A
- wind (sea) waves
- swell waves
7
Q
wind waves
A
- depend on local wind field
- shorter waves and periods
- wide frequency band`
8
Q
swell waves
A
- independant on the local wind field
- have long wave lengths and large wave periods
- all waves lengths and large wave periods
- fairly uniform
9
Q
When both sea and swell waves present
A
bi - modal sea
10
Q
linear wave theory
A
- mathematically describes water waves and their propagation
- provide wave parameters for coastal engineering applications
-can be used to calculate sediment transport and beach change - used to determine wave energy
11
Q
LWT assumptions
A
- fluid incompressible
- fluid is inviscid
- flow is irrotational
- surface tension negligible
- gravity waves sinusoidal (cosine) in shape
- sea bed horizontal
- wave two dimensional
- pressure at the free surface is constant
12
Q
wave number (k)
A
2(pi) / L
13
Q
wave celerity
A
the speed with which a wave crest moves
14
Q
Wave dispersion
A
water waves with different frequencies travel at different speeds
- wave period is a constant
- wave length varies with water depth
15
Q
Approximations - dispersion relationship (deep)
A
valid if the water depth h is much greater than the wavelength L
