Water parks have featured wave pools since the 1960s, with very few modifications over the years. The technology behind wave production may appear simple, but commercial wave pools must take this technology and move tremendous amounts of water on a daily basis. How they accomplish this feat is a combination of fluid dynamics and engineering on a very large scale.
This may not sound like the most appealing comparison, but wave pools work much like flush toilets in some respects. In a toilet, water is introduced by a feeder line to a large storage tank. When the operator wishes to flush, a valve is forced open at the bottom of the tank and the water is forced out through the opening and into the bowl itself. Pipes help to direct the flow to the appropriate areas and the waste water is expelled. The valve then closes and the reserve tank is refilled by the feeder line. Within a few minutes the tank holds enough water for another flush.
In a typical wave pool, the feeder lines are actually a series of powerful water pumps which draw water from a deep well supplied by a city water system or natural reservoirs. These pumps fill a huge tank located behind the wave pool. Water recycled from previous waves also returns to fill this tank. Once the tank has reached its capacity (which can be hundreds of thousands of gallons of water or more), a carefully choreographed process begins.
A hole in the front bottom of the tank is closed by a valve plate which swings freely from an extended arm. When a wave is desired, a timer sends an electronic signal to a solenoid switch- basically an electrical trigger. The switch releases a very powerful hydraulic system which pushes a ‘battering ram’ towards the upper arm of the valve plate assembly. This action must be performed with tremendous force. The valve plate is pushed away from the hole in the giant tank. This would be the equivalent of kicking out the plug holding back the water in a toilet tank, only with a lot more force and a lot more water.
Once the ramrod pushes the valve plate away, the water escapes down the hole with a tremendous amount of force. Reinforced pipes direct this water to a slight u-bend, which forces the water up and back. As the water recovers from this change in course, it crashes over the top of the bend in a large wave formation. This wave will continue until it finally dissipates at the shallowest end of the public pool area. Some of the water will remain in the swimming area of the pool, but most of the water will be drawn back to the original holding tank. The water pumps will continue to pump water back into the holding tank, and the valve plate will naturally fall back into place over the hole. Water pressure will hold it in place until the next time the battering ram decides to kick it out of place again.
The trick with wave pools is to time the waves so that the tank has enough time to recover a sufficient amount of water. If the water pumps can refill the main holding tank quickly enough, some very generous waves can be created. If the timing is off and the tank is only partially filled, the effect is minimized. Most wave pools are designed to withstand a substantial amount of stress, but occasionally the pumps may fail or the hydraulics controlling the ‘battering ram’ piston may lose pressure. Some parks actually use vegetable oils in their pistons in order to avoid contamination of the pool water.