AbstractIn the present paper, the performance of active absorption systems based on nearfield surface elevation measurements is studied. Based on linear wavemaker theory the performance of such systems can easily be calculated for linear waves. A recent study demonstrated that bound superharmonics in regular waves is also well absorbed by such system and has a re-reflection similar to a linear component. However, the performance of active absorption systems on nonlinear irregular waves has never been studied. In the present paper the absorption of bound sub and superharmonics in bichromatic and irregular waves is examined based on new model tests. The conclusion is that also in irregular waves the bound harmonics are well absorbed by the studied active absorption system.
Aalborg University (2018a). AwaSys webpage, www.hydrosoft.civil.aau.dk/awasys
Aalborg University (2018b). WaveLab webpage, www.hydrosoft.civil.aau.dk/wavelab
Biésel, F. and Suquet, F. (1951). Les Appareils generateurs de Houle en Laboratoire. La Houille Blanche, Vol. 6, nos. 2,4 et 5.
Chatry, G., Clement, A. H., Gouraud, T. (1998). Self-adaptive control of a piston wave absorber. Proceedings of the 8th Int. Offshore and Polar Eng. Conference, pp.127-133.
Clavero, M., Aguilera, L., Nieto, S., Longo, S. and Losada, M. A. (2013). Experimental study of the interaction atmosphere-ocean. XII Coast and Ports Spanish Conference. Cartagena (Spain). In Spanish.
Eldrup, M. R. and Lykke Andersen, T. (2018). Applicability of Nonlinear Wavemaker Theory. Proc. CoastLab2018 conference, Santander, Spain.
Eldrup, M. R. and Lykke Andersen, T. (2019). Estimation of Incident and Reflected Wave Trains in Highly Nonlinear Two-Dimensional Irregular Waves. Journal of Waterway, Port, Coastal, and Ocean Engineering, Vol. 145, Issue 1 (January 2019).
Frigaard, P. and Christensen, M. (1994). An Absorbing Wave-maker Based on Digital Filters. Proceedings of the 24th International Conference on Coastal Engineering, Kobe, Japan
Gilbert, G. (1978). Absorbing wave generators. Hydraulic Research Station, Note 20.
Hald, T. and Frigaard, P. (1996). Performance of Active Wave Absorption Systems: Comparison of Wave Gauge and Velocity Meter based Systems, Proc. 2nd International Conference on Coastal, Ports, and Marine Structures "ICOPMAS", Tehran, Iran.
Hald, T., Frigaard, P. (1997a). Performance of Active Wave Absorption Systems: Comparison of Wave Gauge and Velocity Meter based Systems. Proceedings of the 7th International Offshore and Polar Engineering Conference, ISOPE, Honolulu, Hawaii, May 1997.
Hald, T. and Frigaard, P. (1997b). Alternative Method for Active Absorption in Multidirectional Waves. Proceedings of the 27th IAHR Congress, San Francisco. IAHR Seminar: Multidirectional Waves and their Interaction with Structures.
Klopman, G., Reniers, A., Wouters, J. and de Haan, T., (1996). Active Multidirectional wave absorption. Abstract, 25th Int. Conf. on Coastal Eng., Orlando, Florida, USA.
Kostese, J. K. (1984). Measurements of beat and set-down beneath wave groups. Proc. Of the 19th Int. Conf. on Coastal Eng., Houston, Texas, USA, pp. 724-740.
Lykke Andersen, T. and Frigaard, P. (2014). Wave Generation in Physical Models: Technical documentation for AwaSys 6. DCE Lecture Notes, Vol. 34, Department of Civil Engineering, Aalborg University.
Lykke Andersen, T., Clavero, M., Frigaard, P., Losada, M. and Puyol, J. I. (2016). A new active absorption system and its performance to linear and non-linear waves. Coastal Engineering Vol.114, Pages 47-60.
Lykke Andersen, T., Eldrup, M. R. and Frigaard, P. (2017). Estimation of Incident and Reflected Components in Highly Nonlinear Regular Waves. Coastal Engineering, Vol. 119, pp 51-64.
Lykke Andersen, T., Eldrup, M.R., Clavero, M. (2018). Separation of Long-Crested Nonlinear Bichromatic Waves into Incident and Reflected Components. Proc. CoastLab2018 conference, Santander, Spain.
Madsen, P. A. and Fuhrman, D. R. (2006). Third-order theory for bicromatic bi-directional water waves. J. Fluid Mech., Vol. 557, pp. 369-397.
Madsen, P. A. and Fuhrman, D. R. (2012). Third-order theory for multi-directional irregular waves. J. Fluid Mech., Vol. 698, pp. 304-334.
Maisondieu, C. and Clement, A. (1993). A realizable force feedback-feedforward control loop for a piston wave absorber. Proceedings of the 8th Int. Workshop on Water Waves and Floating bodies, St Johns Newfoundland, Canada, pp.79-82.
Milgram, J. H. (1965). Compliant Water Wave Absorbers. Massachusetts Institute of Technology, Department of Naval Architecture and Marine Engineering Research Report no. 65-13, Cambridge, Massachussetts.
Milgram, J.H. (1970), Active Water-wave Absorbers. J. Fluid. Mech., Vol. 43(4), pp 845-859.
Schäffer, H.A., Stolborg, T., Hyllested, P. (1994). Simultaneous Generation and Active Absorption of Waves in Flumes. Proceedings of Int. Symp.: Waves - Physical and Numerical Modelling, Vol. 1, Vancouver.
Schäffer, H.A. (2001). Active Wave Absorption in Flumes and 3D Basins. Proc. 4th Int. Symp. on Ocean Wave Measurement and Analysis, San Francisco, CA, USA, pp. 1200-1208.
Schäffer, H. A. and Jakobsen, K. P. (2003). Non-linear wave generation and active absorption in wave flumes. Proc. Long Waves Symposium, Thessaloniki, Greece, pp. 69-77.
Schäffer, H. A. and Steenberg, C. M. (2003). Second-order wavemaker theory for multidirectional waves. Ocean Engineering 30, pp 1203-1231.
Spinneken, J. and Swan, C. (2009). Wave Generation and Absorption Using Force-Controlled Wave Machines. Proc. 19th Int. Offshore and Polar Eng. Conf. (ISOPE), Osaka, Japan.
Zhang, H., Schäffer, H.A., Jakobsen, K.P. (2007). Deterministic combination of numerical and physical coastal wave models. Coastal Engineering 54, pp 171-186.