Notes on planning

As a result of the functional principle associated with pneumatically operated machines the waves produced are very smooth and calm. They flow through the various sections of the pool and it’s only when approaching “the beach” (ascending sole) that they break and transform into surf. The shape of the wave is essentially determined by the relationship between water depth and wave length. Here one must distinguish, in particular, between deep water waves where the ratio between water depth and wave length is larger than 0.5 so that the sole of the pool has no influence on the wave’s shape. Such waves do not occur in wave pools because of the existing pool depth.

Flat waves are waves where the ratio between water depth and wave length is about 0.2 and where the wave pattern just about retains its distinction.  This type of wave is created normally in pools with a depth of approx. 2.5 m and wave length of approx. 12 m.

Surge waves are waves with a ratio of roughly 0.05 between water depth and wave length which is reached in the flat part of the pool just before they break. The wave height, however, remains in tact but the length shortens so that the wave becomes steeper and steeper. At an assumed wave length of 12 m - the point at which the wave breaks - corresponds to a water depth of approx. 60 cm. typical wave shapes are depicted in the sketch number 1.
 

A wave breaks at a certain water depth (see point 3), mainly because the circular water particles in the wave are braked on the floor of the pool so that the higher transverse strain existing at that point in relation to the pool floor allows the particles in the crest of the wave to collapse.  

The nature of the surf depends to a large extent on the incline of the sole. If the incline is under 8%, a surge breaker - normally desired for wave pools - cannot be generated with certainty. In most cases so-called foam breaker is the result. 

Plunging breakers occur at sole inclines of between 8 and 16%. On larger inclines, so-called swell breakers are produced, which represent an added source of danger, especially for little children. Non-slip tiles should be used in this part of the pool without fail. The various types of breakers are depicted in the sketch No. 2.  

When the sole incline is smaller than 8% in an existing pool, the wave steepness can be increased within certain limits by stepping up the frequency, thus pushing the transient point where foam breakers become plunging breakers to a smaller incline.  

When all wave cells / wave cell flaps are operated in one and the same direction on pneumatic machines, the crest of a wave is produced parallel to the head end of the pool; the wave wanders through the pool in the longitudinal direction. A special “standing wave” is produced (when the wave machine is operated at the natural frequency of a cuboid pool) on which the location of the wave maxima and minima is always identical (so-called swing wave). When the outer wave cells are driven with a time lapse against the inner cells this produces “diamond waves”. Here a valley is created between a wave crest on the left and the opposite pool longitudinal wall on the right in the pool longitudinal axis. Further wave patterns can be generated by modifying the flap control and frequency.