American Society of Civil Engineers


Hydrodynamic Characteristics of a Free-Surface Semicircular Breakwater Exposed to Irregular Waves


by Hee Min Teh, Ph.D., (Student, Institute for Energy Systems, School of Engineering, Univ. of Edinburgh, King’s Buildings, Edinburgh, EH9 3JL, UK. E-mail: H.Teh@ed.ac.uk), Vengatesan Venugopal, (corresponding author), (Lecturer, Institute for Energy Systems, School of Engineering, Univ. of Edinburgh, King’s Buildings, Edinburgh, EH9 3JL, UK. E-mail: V.Venugopal@ed.ac.uk), and Tom Bruce, (Senior Lecturer, Institute for Energy Systems, School of Engineering, Univ. of Edinburgh, King’s Buildings, Edinburgh, EH9 3JL, UK. E-mail: Tom.Bruce@ed.ac.uk)

Journal of Waterway, Port, Coastal and Ocean Engineering, Vol. 138, No. 2, March/April 2012, pp. 149-163, (doi:  http://dx.doi.org/10.1061/(ASCE)WW.1943-5460.0000116)

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Document type: Journal Paper
Abstract: A free-surface semicircular breakwater (SCB) has been developed for protecting coastal and marine infrastructures against ocean waves. The hydrodynamic characteristics of the breakwater are investigated in irregular seas through an experimental program. A test model of the semicircular breakwater has been constructed with front wall porosity varied at 0 (i.e., no perforations), 9, 18, and 27%. The wave surface elevations are measured at different locations upstream and downstream of the models, and the coefficients of wave transmission, reflection, and energy dissipation are evaluated. Wave climate in the vicinity of the breakwater models and horizontal wave force on them are also measured. On the basis of the measured data, empirical models are proposed to provide design formulas for wave transmission, wave reflection, and horizontal wave force. The proposed empirical models show good agreement with the measured data; however, sensible engineering judgment must be taken while using these because the equations proposed are based on small-scale laboratory tests. The overall results indicate that the impermeable SCB model is an effective wave reflector, and the permeable SCB models are good energy dissipaters.


ASCE Subject Headings:
Free surfaces
Breakwaters
Wave reflection
Energy dissipation
Wave forces
Hydrodynamics

Author Keywords:
Free-surface breakwater
Semicircular breakwater
Perforation
Wave transmission
Wave reflection
Energy dissipation
Horizontal wave forces