Water wave radiation by bottom-mounted surface-piercing concentric cylinders

The impact of hydrodynamic forces on the safety of structures under earthquake action cannot be ignored. Within the framework of linear potential flow theory, an analytical solution is developed for the wave radiation problem of concentric cylinders in stationary water using the method of eigenfunction expansion, which is the theoretical basis for earthquake -induced hydrodynamic forces. The inner cylinder of the concentric structure is non -porous, while the outer cylinder is porous, and both inner and outer cylinders are bottom -mounted and surface -piercing. The porous boundary conditions for the outer cylinder are assumed using the fine pores assumption and treated with Darcy's law. It is assumed that the concentric cylinders undergo oscillations due to horizontal ground motion, leading to the generation of radiated velocity potential. The flow field is divided into two domains, inner and outer, and the unknown coefficients in the radiated velocity potentials of the two domains are solved using a domain -matching approach. Added mass, damping coefficient and radiation wave force are then calculated directly from the radiated potentials. The influence of the outer cylinder permeability, radius ratio, and the water depth on the wave radiation process is discussed and suggestions for engineering applications are proposed.