Experimental and numerical determination of the optimum configuration of a parabolic wave extinction system for flumes

Abstract

[EN]In this work the phenomenon of the wave reflection has been studied using a self-developed passive extinction system. Twenty one type of waves were generated in the laboratory using a piston-type wave maker. The variation of the reflection coefficient, Kr, was studied at several depths (h [m] of 0.3, 0.4, and 0.5), periods (0.636 < T [s] < 1.526), wave heights (0.010 < H [m] < 0.064), slopes (3 < α [°] < 17) and vertical end positions of the extinction system (y1 [m] and y2 [m] defined by y1 [m] and α [°]), covering the linear and non-linear regions of the “Le Méhauté” chart. In parallel, an unsteady numerical model based on the Eulerian multiphase VOF was designed and validated according to the free surface displacement, ɳi, and the calculation of the Kr values. Both type of validations were successful so this model was used in order to determine Kr values at slopes [°] that could not be physically reached by the extinction system. The obtained results allowed to determine the minimum Kr values for each set of experiments and finding a useful non-dimensional relationship of Kr,(h-y1)/λ and Ir as a function of the dispersion parameter, kh.