Influence of wave board type on bounded long waves

Abstract

The long wave energy attached to the grouping of natural waves has been shown to play a very important role in the design of mooring systems, offshore terminals, floating structures, harbours, etc. Therefore, in model testing, efforts should be made to reproduce only the correct amount of long wave energy present in nature. However, when only traditional first-order control signals are applied to the wave generator errors will be introduced. Hence, a second-order signal has to be calculated and imposed in order to obtain satisfactory long wave conditions in the physical model. The necessary signal and transfer functions are outlined below for all common types of wave boards. It is demonstrated that dependent on the type (piston, hinged, etc.) considerable differences can be found in the amplitude of the required second-order control signal. Also the erroneous longwave energy is assessed in case of only first-order wave generation. The results indicate that in such situations significant deviations from th...