Approximate calculation method of hydrodynamic solution of an array with a large number of truncated cylinders

Based on linear wave theory, the hydrodynamic problem of the array of truncated cylinders with relative motion is studied, and the calculation formulas of hydrodynamic force/moment, added mass, and added damping coefficients are given. Firstly, the effect of the evanescent mode on the hydrodynamic coefficients are studied by the truncated two-cylinders as an example. And based on this, an approximation formula for the heave added mass of the truncated two-cylinders is given. After that, a fast formula for calculating the added mass coefficient of an oscillating cylinder of the rectangularly arranged array with a large number of cylinders caused by evanescent mode is presented. Finally, the approximate calculation method of the hydrodynamic coefficients for a large number of rectangular arrays with a given amplitude are summarized. The method is able to efficiently solve the hydrodynamic coefficients of the array with a large number of cylinders, providing an idea to evaluate the performance of such models in engineering.