SIMULATION OF EXTREME EVENTS OF OBLIQUE WAVE INTERACTION WITH POROUS BREAKWATER STRUCTURES

Bjarne Jensen, Erik Damgaard Christensen, Niels Gjøl Jacobsen

Abstract


This paper introduces a numerical approach for the analysis of extreme events of wave interaction with coastal and ma- rine structures. The method is exemplified by investigating oblique wave interactions with a rubble mound breakwater structure. The use of numerical models for analysis of wave-structure interaction is seen more often. For many appli- cations a two-dimensional approximation is valid, however, for investigating complex structural details or e.g. oblique wave interaction with coastal structures, a three-dimensional simulation is required. One challenge for a practical use of three-dimensional simulations is the computational cost. For extreme event analysis it is necessary to determine the characteristics of the extreme events which will occur during an irregular sea state of a given duration. Therefore the complete irregular sea state must be simulated. A three-dimensional simulation of a full irregular sea state with duration of e.g. 3 hours will be a large computational burden. The present work proposes a methodology where the analysis is performed in two steps. 1) A two-dimensional simulation of a full 3 hour irregular sea state is performed including the breakwater structure. The extreme events are observed in terms of loads on the super-structure. 2) The extreme events are reproduced in a three-dimensional model as oblique waves by short realizations. The method was validated by comparing the surface elevation and sea-wall forces from a full irregular sea state to the short reproduction sequences. Good agreement was found for both surface elevation and horizontal sea-wall forces. The short reproduc- tion of extreme events was applied in a three-dimensional setup for investigating the effect of oblique waves. For an incident wave angle of 30◦ a reduction of the peak impact load of 25 − 50 % was found for the tested extreme events.

Keywords


Wave-structure interaction; Extreme events; Rubble mound breakwaters; Porous media; Navier-stokes equations; OpenFoam

Full Text:

PDF

References


Antohe, B. V. and Laget, J. L. (1997). A general two-equation macroscopic turbulence model for incom- pressible flow in porous media. International Journal of Heat and Mass Transfer, 40(13):3013–3024.

Berberovic ́, E., van Hinsberg, N., Jakirlic ́, S., Roisman, I., and Tropea, C. (2009). Drop impact onto a liquid layer of finite thickness: Dynamics of the cavity evolution. Physical Review E, 79(3).

Bredmose, H., Peregrine, D. H., and Bullock, G. N. (2009). Violent breaking wave impacts. Part 2: mod- elling the effect of air. Journal of Fluid Mechanics, 641:389.

Bullock, G., Obhrai, C., Peregrine, D., and Bredmose, H. (2007). Violent breaking wave impacts. Part 1: Results from large-scale regular wave tests on vertical and sloping walls. Coastal Engineering, 54(8):602–617.

Burcharth, H. and Andersen, O.H. (1995). On the one-dimensional steady and unsteady porous flow equations. Coastal Engineering, 24(3-4):233–257.

Burcharth, H., Frigaard, P., Uzcanga, J., Berenguer, J., Madrigal, B., and Villanueva, J. (1995). Design of the Ciervana Breakwater.

del Jesus, M., Lara, J. L., and Losada, I. J. (2012). Three-dimensional interaction of waves and porous

coastal structures Part I: Numerical model formulation. Coastal Engineering, 64:57–72.

Engelund, F. (1954). On the laminar and turbulent flows of ground water through homogeneous sand. Technical report, Danish Academy of Technical Sciences.

Forristall, G. Z. (2000). Wave Crest Distributions: Observations and Second-Order Theory. Journal of physical oceanography, pages 1931–1943.

Higuera, P., Lara, J. L., and Losada, I. J. (2014a). Three-dimensional interaction of waves and porous coastal structures using OpenFOAM . Part I: Formulation and validation. Coastal Engineering, 83:243–258.

Higuera, P., Lara, J. L., and Losada, I. J. (2014b). Three-dimensional interaction of waves and porous coastal structures using OpenFOAM . Part II: Application. Coastal Engineering, 83:259–270.

Hsu, T. (2002). A numerical model for wave motions and turbulence flows in front of a composite break-

water. Coastal Engineering, 46(1):25–50.

Jacobsen, N. G., Fuhrman, D. R., and Fredsøe, J. (2012). A wave generation toolbox for the open-source

CFD library : OpenFoam . International Journal for Numerical Methods in Fluids, 70:1073–1088.

Jacobsen, N. G. and Fredsøe, J. (2014). Cross-Shore Redistribution of Nourished Sand near a Breaker Bar.

Journal of Waterway, Port, Coastal, and Ocean Engineering, (March/April):125–134.

Jensen, B., Jacobsen, N. G., and Christensen, E. D. (2014). Investigations on the porous media equations and resistance coefficients for coastal structures. Coastal Engineering, 84:56–72.

Jensen, O. J. (1984). A Monograph on Rubble Mound Breakwaters. Danish Hydraulic Institute, Agern Alle 5, DK-2970 Hoersholm, Denmark.

Lara, J. L., del Jesus, M., and Losada, I. J. (2012a). Three-dimensional interaction of waves and porous coastal structures Part II: Experimental validation. Coastal Engineering, 64:26–46.

Lara, J. L., Higuera, P., Maza, M., del Jesus, M., Losada, I. n. J., and Barajas, G. (2012b). Forces induced on a vertical breakwater by incident oblique waves. In International Conference on Coastal Engineering, pages 1–10.

Liu, P. L.-F., Lin, P., Chang, K.-A., and Sakakiyama, T. (1999). Numerical modeling of wave interaction with porous structures. Journal of Waterways, Port, Coastal and Ocean Engineering, 125:322–330.

Matsumoto, A., Mano, A., Mitsui, J., and Hanzawa, M. (2012). Stability prediction on armor blocks for submerged breakwater by computational fluid dynamics. In International Conference on Coastal Engineering, pages 1–14.

Nakayama, A. and Kuwahara, F. (1999). A macroscopic turbulence model for flow in a porous medium. Journal of fluids engineering, 121(June):427–433.

Schäffer, H., Stolborg, T., and Hyllested, P. (1994). Simultaneous generation and active wave absorption of waves in flumes. In Proc. Int. Symposium: Waves-Physical and Numerical Modelling, pages 90–99. Univ. British Colombia, Vancouver, Canada.

Stahlmann, A. and Schlurmann, T. (2012). Investigations on scour development at tripod foundations for offshore wind turbines: modeling and application. In International Conference on Coastal Engineering, pages 1–11.

van Gent, M. R. A. (1995). Porous Flow through Rubble-Mound Material. Journal of Waterway, Port, Coastal, and Ocean Engineering, 121(3):176–181.

Wellens, P. and van Gent, M. (2012). Wave-induced setup inside permeable structures. In International Conference on Coastal Engineering, pages 1–14.

Zanuttigh, B. and Van der Meer, J. (2006). Wave reflections from coastal structures. In International Conference on Coastal Engineering, pages 1–13.

Zelt, J. A. and Skjelbreia, J. E. (1992). Estimating incident and reflected wave fields using an arbitrary number of wave gauges. In International Conference on Coastal Engineering, pages 777–789.




DOI: https://doi.org/10.9753/icce.v34.structures.1