Experimental and Numerical Investigation of Degree of Freedom Effects on Hydrodynamic Performance of Floating Breakwaters Under Regular Waves

Document Type : Original Research Article


1 PhD. in marine engineering, University of Hormozgan

2 Assistant professor, University of Hormozgan

3 Professors, University of Tabriz

4 Associate professor, University of Tabriz


In designing of any system that deals with forces and displacements some of the effective parameters on hydrodynamic behavior that needs to be investigated are the degree of freedom, and the stiffness of the support systems. In the present study, the effects of degree of freedom on hydrodynamic performance of a box type floating breakwaters (FB) is investigated experimentally and numerically. The experiments were conducted in the 2D wave flume of the (SCWMRI). Regular waves were generated by a piston type wave paddle controlled by ‘DHI wave generating’ software. The effect of incident waves characteristics on efficiency of FB is examined in four configurations. In this paper, a new dimensionless parameter (DB/L2, i.e., draft times width divided by wavelength squared) is identified as an essential parameter for comparison between theories and the experimental data. Generally, the most efficient configuration is the fixed breakwater, but considering the tidal phenomenon, providing the required draft of FB will increase the cost of project. For short wavelengths, it is seen that the efficiency of pile-restrained FB is good same as the fixed type in mild conditions. Regarding the cost-effectiveness, the configuration of the FB with the pile should be considered the most efficient for design purposes in mild conditions. 


This is an open access article under the CC BY license

  1. McCartney, B.L., (1985), Floating Breakwater Design, Journal of Waterway, Port, Coastal, and Ocean Engineering, Vol.111(2), p.304-318.
  2. Biesheuvel A.C, (2013), Effectiveness of floating breakwaters, Msc Dissertation, Delf University of Technology.
  3. Mansard, E., and Funke, E., (1980), The measurement of the incident and reflected spectra using the least squares method, In: Proceedings of the 17th Coastal Engineering Conference ASCE, Sydney, p.154-172.
  4. Koutandos, E.V., Prinos, P., and Gironella, X., (2005), Floating breakwaters under regular and irregular wave forcing: reflection and transmission characteristics, Journal of Hydraulic Research, Vol.43(2), p.174-188.
  5. Ruol, P., Martinelli, L., and Pezzutto, P., (2013a), Formula to predict transmission for π-type floating breakwaters, Journal of Waterway, Port, Coastal, and Ocean Engineering, Vol.139(1), p.1-8.
  6. Ruol, P., Martinelli, L., and Pezzutto, P., (2013b), Limits of the new transmission formula for π-type floating breakwaters, Coastal Engineering Proceedings, Vol.1(33), p.47.
  7. Ursell, F., (1974), The effect of a fixed vertical barrier on surface waves in deep water, In Proc. Cambridge Philos. Soc, Vol.43, p.374-382.
  8. Macagno, E., (1954), Wave action in a flume containing a submerged culvert, La Houille Blanche.
  9. Pena, E., Ferreras, J., Sanchez-Tembleque, F., (2011), Experimental study on wave transmission coefficient, mooring lines and module connector forces with different designs of floating breakwaters, Journal of Ocean Engineering, Vol.38, p.1150-1160.
  10. Abul-Azm, A.G., Gesraha, M.R., (2000), Approximation to the hydrodynamics of floating pontoons under oblique waves, Journal of Ocean Engineering, Vol.27, p.365-384.
  11. Bettess, P., Liang, S.C., and Bettess, J.A., (1984), Diffraction of waves by semi-infinite breakwater using finite and infinite elements, International Journal for Numerical Methods in Fluids, Vol.4(9), p.813-832.
  12. Brebner, and Ofuya, A.O., (1968), Floating breakwaters, In Proceedings of 11th Conference on Coastal Engineering, p.1055-1094.
  13. Cox, R., Coghlan I., and Kerry, C., (2007), Floating breakwater performance in irregular waves with particular emphasis on wave transmission and reflection, energy dissipation, motions and restraining forces, Coastal Structures Conference, Venice.
  14. Kriebel, D.L., and Bollmann, C.A., (1996), Wave transmission past vertical wave barriers, In Coastal Engineering Conference, Vol.2, p.2470-2483.
  15. Gesraha, M.R., (2006), Analysis of π-shaped floating breakwater in oblique waves: I. Impervious rigid wave boards, Journal of Applied Ocean Research, Vol.28, p.327-338.
  16. Drieman, R., (2011), Feasibility study on the use of a floating breakwater to protect a new artificial beach in Balchik, Bulgaria, Msc thesis, Delft University of Technology.
  17. Fousert, M.W., (2006), Floating breakwaters, Msc thesis, Delft University of Technology.
  18. Hales, L.Z., (1981), Floating breakwaters: State of the art literature review, Technical report, DTIC Document.
  19. Dong, G.H., Zheng, Y.N., Li, Y.C., Teng, B., Guan, C.T., and Lin, D.F., (2008), Experiments on wave transmission coefficients of floating breakwaters, Journal of Ocean Engineering, Vol.35, p.931–938.
  20. He, F., Huang, Zh., and Wing-Keung Law, A., (2013), An experimental study of a floating breakwater with asymmetric pneumatic chambers for wave energy extraction, Journal of Applied Energy, Vol.106, p.222-231.
  21. Ji, Ch., Cheng, Y., Cui J., Yuan, Zh., and Gaidai, O., (2018), Hydrodynamic performance of floating breakwaters in long wave regime: An experimental study, Journal of Ocean Engineering, Vol.152, p.154-166.
  22. Liu, Zh., Wang, Y., Wang, W., and Hua, X., (2019), Numerical modeling and optimization of a winged box-type floating breakwater by Smoothed Particle Hydrodynamics, Journal of Ocean Engineering, Vol.188, p.106246.
  23. Williams, A.N., Lee, H.S., and Huang, Z., (2000), Floating pontoon breakwaters, Journal of Ocean Engineering, Vol.27, p.221-240.
  24. Harms, V.W., (1979), Data and procedures for the design of floating tire breakwaters, Water Resources and Environmental Engineering Rep, No.79-1, Dept of Civil Eng., State University of New York at Buffalo.
  25. Harms, V.W., Westerink, J.J., Sorensen, R.M. and McTamany, J.E., (1982), Wave transmission and mooring force characteristics of pipe-tire floating breakwaters, Technical Paper No. 82-4, US. Army, CERC.
  26. Carr, J.H., (1951), Mobile Breakwaters, Proceeding of the Second Conference on Coastal Engineering, Vol.28(1), p.281-295.
  27. Yamamoto, T., (1982), Moored floating breakwater response to regular and irregular waves, Journal of Applied Ocean Research, Vol.3, p.114-123.
  28. Yamamoto, T., Yoshida, A., and Ijima, T., (1980), Dynamics of elastically moored floating objects, Journal of Applied Ocean Research, Vol.2, p.85-92.
  29. Mohammd-Beigi.K, M., Kazeminezhad, M.H., Yeganeh-Bakhtiary, A., (2018), Numerical Study on Hydrodynamic Force and Wave Induced Vortex Dynamics around Cylindrical Pile, IJCOE, Vol.3, No.4, p.1-11.
  30. Zabihi, M.K.Kh., Mazaheri, S., Rezaee Mazyak, A., (2017), Wave Generation in a Numerical Wave Tank, IJCOE, Vol.2, No.4, p.33-43.