Theoretical and Experimental Study on a Porous Cylinder Floating in Waves

In the present work, theoretical and experimental studies on the interaction of water waves with a truncated circular cylinder were performed. The cylinder, which is partly made of porous materials, possesses a porous sidewall and an impermeable bottom. A nondimensional parameter b is adopted in the theoretic formulation to describe the porosity, which is not directly related to the opening ratio τ of the porous materials. To validate the theoretical work and computed results, a series of model tests are carried out in a wave basin. Effort is made to establish an empirical relation between b and τ based on the comparison of the calculation and experimental data. The phenomenon of the sloshing mode that occurred at a certain wave number is observed, which might have an application in breakwaters. The validation of the Haskind relations is examined for the porous body. It is found that the damping coefficient consists of two parts. In addition to the component of conventional wave-radiating damping, there exists a second component caused by the porous effects.