Building a Simple (and Inexpensive)
Wave Generation Model
Bruce "Snake" Gabrielson, PhD
Years ago I was continually asked to demonstrate the effects of bottom slope and contour on wave shape by students during my lectures. Since waves are scalable, shape is the most important consideration for the simulation design. After thinking the problem through, I finally came up with a design that was inexpensive to build, I could transport and set-up easily, and would effectively demonstrate what I was talking about. I built the first model in 1981, but it wasn't sturdy enough to survive more than a few road trips. The second model, built from stainless steel, is still useable after nearly 15 years. I've provided this design to many students for graduate projects. I should also mention that although a little messy, the model can also be used to demonstrate beach erosion.
This is what I initially did to look at simple wave shapes and keep my costs down. I built a rectangular water container from stainless steel. Mine is approximately 2 1/2 ft by 4 1/2 feet so it will fit into the back of a car, but I now feel a better container would be 3 ft by 5 ft. The sides should be at least 8 inches high (8 would be better), and all seems should be welded. This makes an easily transportable pool that can sit on a table.
To generate the wave, I built a simple arrangement from a 2" by 4" mounted in a wooden bracket at one end of the pool. At first I could generate waves by pushing up and down. Now I have a pneumatic plunger so I can measure exact pressure. Remember that reflections from the pool end and sides will quickly ruin your waveshape, unless your model channels the reflection, after 2 or 3 successive generations. So you don't need something that produces a constant up and down motion.
The bottom designs are heavy but also rugged. They can be cheaply built with concrete on top of a piece of 1/4 inch plywood that fits inside your pool. Use wet but not runny concrete and hand shape the design you want. Make sure you use rubber gloves or your hands will suffer. Also, build the bottom model outside as it will be messy. Once the concrete gets hard in a few days, spray it with water sealant or it will crack easily. Also, don't handle the bottom model too rough or it will crack and separate from the plywood. One way to prevent this is to pound some short nails from the bottom through the plywood before making the concrete model and then shaping the concrete around the nails. Cut off any nail tips that stick up through the concrete. I painted my bottom models white and use slightly tinted water so the wave action shows up better. Remember, your looking at the break from above.
I built five models over a two-year period. My first was terrible but my last worked quite well. The model is really trial and error. Expect to make a couple mistakes before you get what you want. Also, don't let the model get above 4 inches high, counting the plywood, or water will spill out of your container.
A number of students have built this pool model over the eyars. I hope this gives you some ideas. I would also be interested in reviewing your dissertation or project report when you complete it. You have my permission to use my name as a reference.
The pictures below are from Pam Shea who built one of these pools for her son's school project. I like them better then pictures of my pool since this pool was built of plexiglass and wave action and underwater structures are clearly visible. The drawback of using plexiglass is that you can't simply lift the pool up to quickly drain it or it will spring a leak. I need to empty and remove my pool very quickly after demonstrations.
View from Beach Towards Plunger
The blocks are marked to allow measurement of wave height with different orientations of the blocks.
View from Plunger Towards Slope in Beach
Veiw Showing a Breaking Wave on the Beach
Notice that by using colored water the wave action is easier to see.
View of Filled Pool With No Waves