Wave filters and absorbers are important coastal structures. Their efficiency depends on wave reflection and transmission as well as on energy dissipation. Because of their nonlinear characteristics, wave filters and absorbers must be analyzed and optimized experimentally. In a more general approach, two universally valid coefficients are determined for each individual filter element. Based on these data, arbitrary, multi-layer wave absorbers can be evaluated. Filter hydrodynamics mainly depend on porosity and wave kinematics, i.e., the profiles of horizontal velocity and acceleration. With reference to an initial wave, the related near-field velocity and acceleration at the filter element are expressed as functions of a drag and an inertia term. The corresponding coefficients, which are universally applicable, in connection with the relevant horizontal velocity and acceleration at the filter area are used to calculate the reflection, transmission, energy dissipation, and wave forces on arbitrary filter or absorber components, elements, and systems. The numerical analysis is validated by an experimental program in regular and irregular seas, and transient wave trains. Transient wave trains are efficiently used for: 1) Separate measurements of the initial wave group, as well as its reflection and transmission. Due to the short duration, the incoming wave train is easily separated from the reflected and the transmitted wave. This allows an accurate analysis of the associated flow fields and energies. For a variety of wave filters, the paper presents the evaluation of the foregoing characteristic coefficients, based on experiments with representative transient wave groups. 2) Model tests in extreme wave conditions (freak waves). Tests with breaking transient wave packets prove that the obtained maximum wave force on a structure is much higher than the long-term model test results in irregular waves, for a given spectrum.

1.
Bennett, G. S., McIver, P., and Smallman, J. V., 1992, “A Mathematical Model of a Slotted Wave Screen Breakwater,” Proceedings of Coastal Engineering, ASCE, pp. 231–249.
2.
Clauss, G. F., 1998, “Task-related Wave Groups for Seakeeping Tests or Simulation of Design Storm Waves,” Real-Sea ’98 International Workshop on Modeling of Ocean Environments in Wave & Current Basin, Taejon, Korea.
3.
Clauss, G. F., and Kuhlmann, G. H., 1995, “Design Aspects of Vertical Wave Absorbers,” Proceedings, 14th International Conference on Offshore Mechanics and Arctic Engineering, Copenhagen, Denmark.
4.
Clauss, G. F., and Ku¨hnlein, W. L., 1994, “Seakeeping Tests of Marine Structures with Deterministic Wave Groups and Tank Side Wall Wave Absorbers,” Proceedings, BOSS Conference, Massachusetts Institute of Technology, Cambridge, MA.
5.
Clauss, G. F., and Ku¨hnlein, W. L., 1997, “Simulation of Design Storm Wave Conditions with Tailored Wave Groups,” Proceedings, 7th ISOPE, The International Society of Offshore and Polar Engineers, Honolulu, HI.
6.
Clauss, G., Lehmann, E., and Ostergaard, C., 1992, “Offshore Structures,” Vol. 1, Conceptual Design and Hydrodynamics, Springer Verlag, London, U.K.
7.
Cummins
W. F.
,
1962
, “
The Impulse Response Function and Ship Motions
,”
Schiffstechnik
, Vol.
9
, pp.
101
109
.
8.
Evans
D. V.
,
1990
, “
The Use of Porous Screens as Wave Dampers in Narrow Wave Tanks
,”
Journal of Engineering Mathematics
, Vol.
24
, pp.
203
212
.
9.
Fugazza, M., and Natale, L., 1992, “Hydraulic Design of Perforated Break-waters,” Journal of Waterway, Port, Coastal, and Ocean Engineering, Proceedings ASCE, Vol. 118, No. 1.
10.
Goda, Y., and Ippen, A. T., 1964, “Theoretical and Experimental Investigations of Wave Energy Dissipators Composed of Wire Mesh Screens,” Technical Report Contract No. Nonr-1841 (59), NR-062-228, Office of Naval Research, U.S. Department of the Navy, Washington, DC, Hydrodynamics Laboratory, Department of Civil Engineering, Massachusetts Institute of Technology, Cambridge, MA.
11.
Jamieson, W. W., and Mansard, E. D. P., 1987, “An Efficient Upright Wave Absorber,” Proceedings, ASCE Specialty Conference on Coastal Hydrodynamics, pp. 1–16. University of Delaware, Newmark, DE.
12.
Jarlan, G. E., 1961, “A Perforated Vertical Wall Breakwater—An Examination of Mass-Transport Effects in Gravitational Waves,” The Dock & Harbor Authority.
13.
Kondo, H., 1979, “Analysis of Breakwaters Having two Porous Walls,” Proceedings, ASCE Conference—Coastal Structures, pp. 962–977.
14.
Kriebel, D. L., 1992, “Vertical Wave Barriers: Wave Transmission and Wave Forces,” Proceedings, 23rd International Conference on Coastal Engineering (ICCE), Venice, Italy.
15.
Macaskill
C.
,
1979
, “
Reflexion of Water Waves by a Permeable Barrier
,”
Journal of Fluid Mechanics
, Vol.
95
(
1
), pp.
141
157
.
16.
Mei
C. C.
,
Liu
P. L.-F.
, and
Ippen
A. T.
,
1974
, “
Quadratic Loss and Scattering of Long Waves
,”
Journal of the Waterways Harbors and Coastal Engineering Division
, Vol.
100
, No.
WW3
, pp.
217
239
.
17.
Morison, J. R., O’Brian, M. P., Johnson, J. W., and Schaaf, S. A., 1950, “The Force Exerted by Surface Waves on Piles,” Pet. Trans. AIME, 189 (T.P. 2846), pp. 149–157.
18.
Urashima, S., Ishizuka, K., and Kondo, H., 1986, “Energy Dissipation and Wave Force at Slotted Wall,” Proceedings of Coastal Engineering, pp. 2344–2452.
19.
Takahashi, S., 1996, “Design of Vertical Breakwaters,” Technical Report Reference Document, No. 34, Reprinting of Coastal Structures (ICCE’96, Short Course).
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