1. Science Modules using the Mini Wave Tank (working document)
Jack A. Puleo, Ph.D.
University of Delaware, Center for Applied Coastal Research
What are Waves
Wave Description
Period and Frequency
Energy Transport
Wave Speed
Shallow versus Deep Water
Tsunami
Beach Profile
View of a breaking wave
from below the surface

2. What is a Wave? Waves are everywhere in nature
Most people think of waves on the ocean when someone mentions waves
But, they exist in many other places:
Here are a few examples: Can you think of more?
Ripples on lake, waving your hand, sound, light etc

3. Wave Description
A wave is a disturbance that travels through some medium (typically air or water) from one place to another.
There are a variety of wave types, but here we will only discuss surface waves
Surface waves travel on the surface of a fluid where particle undergo a circular motion
For simple surface waves, the water particles have no net displacement. The individual particles return to where they started from.

4. WAVE PARAMETERS
Wave elevation profile: deep water = sine wave
Wavelength
Crest
amplitude
Height
Rest position
Trough
Crest: location of maximum upward displacement
Trough: location of maximum downward displacement
Amplitude (a): amount of maximum displacement from rest position
Height (H): vertical distance between trough and crest
Wavelength (L): The horizontal length of a complete wave cycle

5. WAVE PARAMETERS
Period (T): time is takes for one cycle to complete
Frequency (f): refers to how often something happens, usually cycles per second. The unit cycles per second is called Hertz (Hz)

6. Velocity (C): distance divided by time
WAVE PARAMETERS
Moving with velocity, C
Velocity (C): distance divided by time
Crests can be seen to move along the ocean, how long it takes the crest to get from one point to another is the velocity.
Velocity (C) = Wavelength/Period = L/T Or
Velocity (C) = Wavelength * frequency = L*f

7. So, waves transport energy, NOT matter.
WAVE PARAMETERS
Low energy
High energy
Energy (E): From the movie we saw that particles return to their original position.
So, waves transport energy, NOT matter.
Wave energy is proportional to the amplitude of a wave SQUARED
Question: If a wave amplitude is doubled, what happens to the energy? Ans: it quadruples.

8. where h is the water depth
WAVE PARAMETERS
Water particle motion within a wave train decays exponentially with depth and varies in shape depending on relative depth.
“Shallow”
“Intermediate”
“Deep”
where h is the water depth
Dean and Dalrymple Coastal Engineering textbook

9. This suggest that the water particle motion changes with depth.
WAVE PARAMETERS
This suggest that the water particle motion changes with depth.
It also suggests that parameters such as velocity and wavelength change with depth
g is gravity; g = 32.2 ft/s2.
“Deep Water”
“Intermediate Water”
“Shallow Water”
Wavelength (L)
Wave velocity (C)
Intermediate requires iteration and too hard to solve at this level.

10. WAVE PARAMETERS T = 10 seconds, H = 6 ft. Intermediate region

11. TSUNAMI
Tsunami are waves that often cause destruction.
They are often incorrectly referred to as tidal waves, but they are not associated with the moon or sun that forces tides.
Tsunamis typically occur after an earthquake where parts of the ocean floor are raised or lowered very rapidly.
They can also be caused by a landslide where lots of dirt and rock quickly enter the ocean.

12. A typical depth for an ocean basin may be 3 miles.
TSUNAMI
The wavelength of a tsunami as it travels across the ocean can be MILES.
A typical depth for an ocean basin may be 3 miles.
Tsunami height can increase drastically when the water depth becomes very shallow

13. Example: it usually gets deeper as you go farther offshore.
BEACH PROFILE
The beach profile is the change in elevation or depth as a function of cross-shore distance.
Example: it usually gets deeper as you go farther offshore.
Imagine staring straight offshore and taking a slice down through the beach.

14. The profile shape is governed by variable waves and currents
BEACH PROFILE
The profile shape is governed by variable waves and currents
During large waves, sand tends to move offshore. Sometimes termed “winter” profile
During small, long period waves sand tends to move onshore. Sometimes termed “summer” profile
SUMMER
WINTER
coastalchange.ucsd.edu

15. BEACH PROFILE
Changes in the beach profile can be simulated in the wave tank by running waves of different size for periods of time.

16. BEACH PROFILE SPREADSHEET
Screen shot of the Excel spreadsheet.