Hydrodynamic Load on Partly Submerged, Floating Elements

The hydrodynamic load models for floating partly submerged elements are relevant for analysis of floating flexible fish farm systems, floating offshore loading hoses, etc.

The load model accounts for the time-varying wetted length of the element due to wave action, which affects the hydrodynamic forces. The hydrodynamic loads are calculated based on the local wetted length and the corresponding hydrodynamic coefficients.

The load model for partly submerged elements is based on the generalized Morison equation, where the Froude-Krylov term is modified to account for the varying submerged area.

The hydrodynamic force at a cross-section is reduced in proportion to the instantaneous wet portion of the cross-section. The Froude-Krylov term used in the longitudinal direction in Morison’s equation is replaced by the product of the dynamic pressure and the submerged area at each end of the element.

If the specified value for external area (AE) is zero, neither hydrostatic nor hydrodynamic loads will act on the cross section. Definitions of dimensional/nondimensional hydrodynamic force coefficients for a fully submerged cross section are given below.

Please refer to the description in Theory - Load models - Hydrodynamic Load on Partly Submerged, Floating Elements.