Analysis of wave generators and absorbers in basins

Abstract

Wave generation and absorption are analyzed in a closed basin, within the framework of linear potential theory. Wavemakers on the sides of the basin are used for both generating and absorbing the waves. Relations are derived governing the control of the absorbers, to reduce or eliminate reflected waves from the walls of the basin. These relations are tested by showing numerical examples of wave systems in square and circular basins, first without a body in the basin and then with a floating hemisphere. Computations of the added mass, damping, and exciting forces on the hemisphere are presented to indicate the effectiveness of the wave absorbers. Two-dimensional results are shown in the time domain to illustrate some of the transient effects associated with different types of absorber controls.

The operation of a 3D wave basin in force control

“…On the contrary, considering the sum of the evanescent modes (j = 1..∞), it is clear that their amplitude decreases with increasing wave propagation angle (Figure 6 (a) and (b)). This decrease is consistent with the findings presented in Schäffer & Steenberg (2003) and Newman (2010). For example, the magnitude of the evanescent mode sum for the piston-type machine shown in Figure 6 (a) decreases from i…”

“…Similar arguments apply to active absorption in multi-directional wave facilities; very limited experimental evidence of their 3D absorption characteristic having been provided over the past decades. To date, there is only one study that discussed the absorption performance of waves in a 3D environment, but this relates to numerical computations (Newman 2010).…”

Nonlinear wave transmission and pressure on the fixed truncated breakwater using NURBS numerical wave tank

“…The wave characteristics might be defined by the wave theories. Different types of wavemakers have been reviewed in detail by Tanizawa (2000) and Newman (2010).Wave absorber is deployed at upstream and downstream boundaries to prevent wave reflection from end walls. This function is essential to maintain unbounded region condition during a long time simulation and to avoid the nonphysical manner due to the propagation of reflected wave from the end walls within the computational domain.…”

Simulation of irregular waves over submerged obstacle on a NURBS potential numerical wave tank

“…Different types of wave-makers on the inflow boundary were reviewed by Tanizawa (2000) and Newman (2010). In the opposite side of the wave-maker, the wave absorber is adopted to prevent wave reflection from the end wall.…”