RD Instruments Home of the ADCP Coastal & Inland Business Unit 1. Why Waves? 2. Waves Features 3....

Acoustic D oppler Solutions

RD InstrumentsHome of the ADCP

Coastal & Inland Business Unit


1.1. Why Waves? Why Waves?

2.2. Waves FeaturesWaves Features

3.3. Waves ObservedWaves Observed





Why Waves? Critical Factor for Coastal RegionCritical Factor for Coastal Region

BeachesBeaches … summer fun, winter destruction … summer fun, winter destruction Coastal economyCoastal economy

SafetySafety Shipping & BoatingShipping & Boating: ocean routes, coastal lanes: ocean routes, coastal lanes Coastal DestructionCoastal Destruction: storm surges, tsunamis: storm surges, tsunamis

Coastal and Offshore EngineeringCoastal and Offshore Engineering Shore Protection, Structures:Shore Protection, Structures: design, survival design, survival Mechanism for restoring natural equilibriumMechanism for restoring natural equilibrium

Energy Source: Energy Source: Wave & Tidal PowerWave & Tidal Power





Specific Examples

Vessel Berthing Structure Design Sediment Transport Estuary Processes Air / Sea Interaction Oil Spill Response





Vessel Berthing

Direction #1

Dire

ctio

n #2

Bia

sed

Dir

ectio

n





Structure DesignTo Build A Jetty

Direction #1

Directi

on #2

Bia

sed

Dire

ctio

n





Sediment Transport

Direction #1

Directi

on #2

Bia

sed

Dire

ctio

n





Background

Wave characteristicsWave characteristics PeriodicPeriodic oscillation that oscillation that propagatespropagates through space through space Transfers Transfers energyenergy but not mass but not mass

Engineering & Science Interest: Engineering & Science Interest: Energy VariationEnergy Variation With frequencyWith frequency

With direction (and frequency)With direction (and frequency)





Describing Waves

FrequencyFrequency (time variation) (time variation)

sets Wavelength for wave typesets Wavelength for wave type

DirectionDirection (propagation through space) (propagation through space) HeightHeight (2 x amplitude) (2 x amplitude) EnergyEnergy (height (height 22) x wavelength) x wavelength





Wave Words

Figures taken from Oceanography of the British Columbia Coast, Richard E. Thompson





Background 1-d … wave propagates along line1-d … wave propagates along line

Single wave: sinusoidal variation, amplitude, periodSingle wave: sinusoidal variation, amplitude, period Wave groupWave group

2-d … wave propagates across plane: direction2-d … wave propagates across plane: direction

Two classes: Two classes: long & shortlong & short wavelength wavelength Relative to water depthRelative to water depth Energy of short waves decays with depthEnergy of short waves decays with depth





Two Wave Types





Wave Orbits





Background Two categories: sea and swell (co-exist)Two categories: sea and swell (co-exist)

SeaSea High frequency, short wavesHigh frequency, short waves Surface variation appears random (snapshot)Surface variation appears random (snapshot) Energy from local windsEnergy from local winds

SwellSwell Lower frequency, longer wavesLower frequency, longer waves Surface appears corrugated (more coherent), Surface appears corrugated (more coherent),

movement of crests more apparentmovement of crests more apparent Energy from distant stormsEnergy from distant storms





Waves Spectrum

WINDWIND

SUN, MOONSUN, MOON

STORMS, TSUNAMISSTORMS, TSUNAMIS

Tides





Storms & Swell

StrengthStrength DurationDuration FetchFetch





Waves at Beach





Refraction at Headland

RD Instruments Home of the ADCP Coastal & Inland Business Unit 1. Why Waves? 2. Waves Features 3....

Documents

Transcript of RD Instruments Home of the ADCP Coastal & Inland Business Unit 1. Why Waves? 2. Waves Features 3....