Mean Drift Loads on Array of Vertical Cylinders in Narrow Tank

The influence of tank walls on the mean drift loads on an array of bottom‐mounted surface‐piercing vertical cylinders of arbitrary uniform cross section in a narrow wave tank is investigated theoretically. The problem is rendered two‐dimensional by specifying analytically the z‐dependency of the linearized velocity potential. Application of Green's second identity, utilizing an appropriate two‐dimensional Green's function, yields an integral equation for the velocity potential on the cylinder surfaces. Discretizing this equation leads to a matrix system for the potential at the nodal points on the cylinders. The mean drift forces and moments on the array members are obtained via a direct pressure integration. A forward difference approximation is used to calculate the fluid velocity components on the cylinders from the corresponding potentials. Numerical results are presented that illustrate the effect of the tank walls on the mean drift loads for various array configurations. It is found that the mean drift loads experienced by the array members in a narrow tank are quite different from those experienced by the same array members in the open sea.