**Giuseppe Tripepi, Francesco Aristodemo \* and Paolo Veltri**

Dipartimento di Ingegneria Civile, Università della Calabria, via Bucci, cubo 42B,

87036 Arcavacata di Rende (CS), Italy; giuseppe.tripepi@unical.it (G.T.); paolo.veltri@unical.it (P.V.)

**\*** Correspondence: francesco.aristodemo@unical.it; Tel.: +39-0984-496554

Received: 28 March 2018; Accepted: 12 April 2018; Published: 16 April 2018

**Abstract:** A two-dimensional (2D) laboratory investigation on the horizontal and vertical hydrodynamic forces induced by tsunami-like solitary waves on horizontal circular cylinders placed on a rigid sea bed is presented. A series of 30 physical model tests was conducted in the wave channel of the University of Calabria in which a rigid circular cylinder was equipped with 12 pressure transducers placed along its external surface to determine the wave loads, with three wave gauges to record the surface elevation. The observed experimental range was characterized by the prevalence of the inertia component for the horizontal forces and of the lift component for the vertical ones. On the basis of the performance of several time-domain methods, the wave loads and the undisturbed velocity and acceleration derived from the surface elevation of the cylinder section were used to calculate the drag, lift, and horizontal and vertical inertia coefficients in the practical Morison and transverse semi-empirical equations.

**Keywords:** tsunami-like solitary waves; horizontal cylinders; hydrodynamic loads; experimental tests; Morison and transverse equations; hydrodynamic coefficients
