Two-dimensional experimental and numerical investigations of parallel perforated plates in oscillating and orbital flows

Abstract

The hydrodynamic loads on two-dimensional perforated plates are investigated experimentally and numerically. Two parallel plate configurations, consisting of an upper perforated plate and a lower perforated plate, are studied. The difference between the two configurations is the gap distance between the upper and the lower plates, being 0.14 and 0.29 times the width of the plates. Comparisons are made between forced oscillation experiments and numerical simulations of oscillating and orbital flow conditions. The Keulegan–Carpenter (KC) number and period of oscillation are varied. Added mass and damping coefficients are presented. The coefficients are highly KC number dependent. There is in general small dependence on the period of oscillation. The force coefficients are in general somewhat larger for the largest gap distance. The hydrodynamic force on both configurations is dominated by damping. We find in general good agreement between the experimental and numerical results. Interaction effects between the plates of the parallel configurations are studied. The interaction effects increase with increasing KC number and depend on the distance between the two plates. Compared to the force on one single perforated plate, interaction effects influence the phase and magnitude of the force on the upper and lower plates in the parallel configurations. A reduction in hydrodynamic force, compared to that of one single plate, is found for both plates, in particular for the downstream plate.