Wave-field Flow Structures Developing around Large-diameter Vertical Circular Cylinder

In this work the issue of wave-induced flow structures that develop around a largediameter surface-piercing vertical circular cylinder is addressed. A strictly-linear wave case is considered and simulated numerically, solving the Euler equations in primitive variables, and the results are compared with those obtained from the corresponding close-form velocity-potential solution. Then, the swirling-strength criterion for flowstructure eduction is applied to the primitive-variable Euler-equations-derived velocity field. It is found that differently-shaped flow structures develop at the free surface and under the free surface, in particular at the cylinder wall. This field of structures is not detectable from the potential-derived velocity field, due to the purely mathematical nature of the latter.