Author(s): Nobuhisa Kobayashi; Andojo Wurjanto
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Abstract: Design of marine structures protected with armor units is presently based onempirical formulas and hydraulic model tests.In most model tests,the detailedhydrodynamics and armor response are not measured because of the difficulties ofinstrumentation.Numerical models are hence needed to improve our understandingof the detailed mechanics and our design capabilities. In this paper,the numerical model developed by Kobayashi et al.(1987)forpredicting monochromatic wave reflection and runup on the rough primary coverlayer of a marine structure is expanded to include a permeable underlayer belowthe primary cover layer.The expanded numerical model is used to predict thefluid velocity and acceleration on the rough permeable slope which determine thedrag,lift and inertia forces acting on an armor unit in the primary cover layer(Kobayashi and Otta,1987).Computed results with and without a permeableunderlayer indicate that the permeability effects increase the hydraulicstability of armor units and decrease wave runup and reflection.The computedresults are qualitatively consistent with available data,although they are notextensive and 1imited to monochromatic waves only.
Year: 1989