ABSTRACT
The hydrodynamic force on a structure immersed in a uniform flow, is commonly split into a component acting in the direction of the approach flow and two components acting perpendicular to it. Hydrodynamic forces on structures can be determined experimentally either directly by force measurement or indirectly by pressure measurements. Extraneously induced excitation (EIE) is caused by fluctuating velocities or pressures which are independent of any flow instabilities originating from the structure and independent of structural motion except for added-mass effects. The most common EIE is turbulence buffeting, for which the fluctuating velocities or pressures are caused by turbulent eddies passing near or impinging on the structure. Belonging to the same category of EIE is the buffeting by vortices which are shed from upstream structures. EIE is possible also due to two-phase or multiple-phase flows. The fluctuating load on a structure is induced by either a gas or a solid, carried along in the liquid flow.
