Efficacy analysis of the length of entrance on the diffraction of waves behind two breakwaters

  • Abstract
  • Keywords
  • References
  • PDF
  • Abstract

    Any harbor should be protected from incoming waves. However, these waves are always diffracted at the entrance of the harbor and a fraction of the waves enters the harbor area. In the present paper, by the use of Boussinesq equations solved by Mike21 numerical software, a parametric study on the length of entrance of a simple harbor has been conducted and the diffraction of waves after passing the harbor entrance has been analyzed. As a result, the effects of the length of the entrance have been investigated on the safe zone behind the breakwaters of the harbor. To this end, a parameter called angle of safety is defined as a representative of the safe zone. Finally, an equation is presented to describe the behavior of the safe zone with respect to the length of the entrance. It has been observed that the angle of safety has a minimum of 57.5 degrees which increases with respect to the length of entrance which consequently increases the safe area behind the breakwaters.

  • Keywords

    Random Wave Diffraction; Breakwater; Mike21, Safe Zone.

  • References

      [1] M.W, Dingemans, “Directional near shore wave propagation and induced currents”, Proceedings of 20th International Conference of Coastal Engineering, ASCE, New York, (1986), pp.1092–1106. https://icce-ojs-tamu.tdl.org/icce/index.php/icce/article/viewFile/4082/3764.

      [2] K.Suh, R.A .Dalrymple, “Offshore breakwaters in laboratory and field”, Journal of Waterway, Port, Coastal, Ocean Engineering, ASCE, New York. Volume 113 (2), (1987), pp. 105–121.http://dx.doi.org/10.1061/(ASCE)0733-950X(1987)113:2(105).

      [3] D. John Pos, F.A. Kilner, “Breakwater Gap Wave Diffraction: an Experimental and Numerical Study”, Journal of Waterway, Port, Coastal, Ocean Engineering, Volume 113(1), (1987), pp. 1–21.http://dx.doi.org/10.1061/(ASCE)0733-950X(1987)113:1(1).

      [4] C.L. Vincent, M.J. Briggs “Refraction–diffraction of irregular waves over a mound”, Journal of Waterway, Port, Coastal, Ocean Engineering, Volume. 115 (2), (1989), pp.269–284.http://dx.doi.org/10.1061/(ASCE)0733-950X(1989)115:2(269).

      [5] S. Elgar, R.T Guza,. M.H. Freilich, M.T. Briggs, “Laboratory simulations of directionally spread shoaling waves” Journal of .Waterway, Port, Coastal, Ocean Engineering, ASCE, Volume 118 (1), (1992), pp. 87–103.

      [6] Y.Suzuki, T. Hiraishi, T. Takayama, N.Ikeda, “Applicability of multi-directional wave experiment for port design”, Proceedings of the International Conference on Hydro-technical Engineering for Port and Harbor Construction, (1994), pp.281–301.

      [7] M. Briggs, E. Thompson, C. Vincent, “Wave Diffraction around Breakwater”,Journal Waterway, Port, Coastal, Ocean Engineering, Volume 121 (1), (1995), pp. 23–35. http://dx.doi.org/10.1061/(ASCE)0733-950X(1995)121:1(23).

      [8] J.A. Zyserman, I. Broker, H.K. Johnson, K. Mangor, K. Togensen, “On the Design of Shore-Parallel Breakwaters”, Journal of Coastal Engineering, (1998), pp. 1693-1705.

      [9] J. Boussinesq, “Théorie des ondes et des remous qui se propagent le long d'un canal rectangulaire horizontal, encommuniquant au liquidecontenudansce canal des vitessessensiblementpareilles de la surface au fond”, Journal de MathématiquesPures et Appliquées. DeuxièmeSérie 17, (1872), pp.55–108.

      [10] A. Madsen, R. Sorensen “A new form of the Boussinesq equations with improved linear dispersion characteristics, Part 2: A slowly-varying Bathymetry”, journal of Coastal Engineering, Volume 18, , (1992), pp. 183-204.

      [11] Y.S. Li., S.X. Liu., Y.X .Yu., G.Z .Lai., “Numerical modeling of multi-directional irregular waves through breakwaters” Journal ofApplied Mathematical Modeling, Volume 24 , Issues 8–9, (2000), pp. 551-574.http://dx.doi.org/10.1016/S0307-904X(00)00003-2.

      [12] K.H .Wang, W. Li, H.S. Lee, “Propagation and transformation of periodic nonlinear shallow-water waves in basins with selected breakwater systems”, Journal of Computers &Fluids,Volume 37, (2008), pp.931–942. http://www.sciencedirect.com/science/article/pii/S0045793007001946.http://dx.doi.org/10.1016/j.compfluid.2007.10.007.

      [13] N.V. Carvalho, R.B. Paes-Leme, D.A. Accetta., F. Ostritz, “Diffraction and reflection of irregular waves in a harbor employing a spectral model”, Journal ofAnais da Academia Brasileira de Ciências,Volume 81(4), (2009), pp. 837-848.http://dx.doi.org/10.1590/S0001-37652009000400019.

      [14] Ilic S., van der Westhuysen A.J., Roelvink J.A., Chadwick A.J., "Multidirectional wave transformation around detached breakwaters", journal ofCoastal Engineering , Volume 54, (2007) , pp.775–789.

      [15] J. Zheng, N.V. Thanh, Z. Chi, “Spectral wave transformation model for simulating refraction-diffraction with strongly reflecting coastal structures” Journal of ActaOceanologicaSinica, Volume 30 (2), (2011), pp.25-32. http://link.springer.com/article/10.1007%2Fs13131-011-0102-y.http://dx.doi.org/10.1007/s13131-011-0102-y.

      [16] Per A. Madsen,R. Murray, Ole R. Sorensen “A new form of the Boussinesq equations with improved linear dispersion characteristics” , journal of Coastal Engineering, Volume 15, , (1991), pp. 371-388. http://www.sciencedirect.com/science/article/pii/037838399190017B

      [17] P. A. Madsen, O. R. Sorensen, H.A Schaffer “Surf zone dynamics simulated by a Boussinesq type model. Part I. Model description and cross shore motion of regular waves”, journal of Coastal Engineering, Volume 32, (1997), pp. 255-287. http://www.sciencedirect.com/science/article/pii/S0378383997000288

      [18] Y.X .Yu, S.X. Liu, Li, Y.S. Wai O.W.H., “Refraction and diffraction of random waves through breakwater”, Journal of Ocean Engineering, Volume 27, (2000), pp.489–509. http://dx.doi.org/10.1016/S0029-8018(99)00005-0.

      [19] O.R. Sorensen, L.S. Sorensen, "Boussinesq type modeling using unstructured finite element techniqe", Journal of Coastal Engineering, (2001), pp. 190-202. http://ascelibrary.org/doi/abs/10.1061/40549%28276%2915.

      [20] O.R. Sorensen, H.A. Schaffer, L.S. Sorensen, "Boussinesq type modeling using unstructured finite element techniqe", Journal of Coastal Engineering, Volume 50 , (2004), pp. 181-198. http://www.sciencedirect.com/science/article/pii/S0378383903001121.http://dx.doi.org/10.1016/j.coastaleng.2003.10.005.




Article ID: 3636
DOI: 10.14419/ijsw.v3i2.3636

Copyright © 2012-2015 Science Publishing Corporation Inc. All rights reserved.