0n Hydrodynamic Influences to a Floating Body by a False-Bottom to Simulate the Shallow Water Condition

Abstract

Hydrodynamic influences to a floating body by a temporal bottom (false-bottm) which is used to simulate the shallow water condition in experimental tank is studied. The numerical method is bassed on potential theory and the velocity potential is represented by the distribution of sources and dipoles over the floating body and the false-bottom. The added mass and damping coefficients of the floating body above various false-bottoms in size and shape are compared and discussed in both calculations and experiments. It is found that the interaction between the floating body and the false-bottom is significant especially at low frequency range of the oscillations and is caused mainly by reflected waves at ends of the false-bottom. Some considerations and proposals on a desirable shape of the false-bottom are discussed to realize appropriate shallow water condition.