Hydrodynamic Load Models

There are various load models that can be used. These can be set in the Hydrodynamic force coefficient tab in the cross sectional properties.

The following load models are available:

  • Morison’s Generalized Equation

    • Use for slender structures where the structural diameter is small relative to the wavelength. This is the standard and most commonly used load model.

  • MacCamy-Fuchs Load Model

    • Use for large-diameter cylindrical structures (e.g. monopiles) where diffraction effects are significant and Morison’s equation is no longer valid. Applicable for bottom-fixed or floating single-column systems.

  • Hydrodynamic Load on Partly Submerged, Floating Elements

    • Use for elements that cross the free surface (partly submerged floating elements) The load model is relevant for analysis of such as floating flexible fish farm systems, floating offshore loading hoses, etc.

    • The model accounts for the time-varying wetted length due to wave action.

  • Potential Flow with Quadratic Load Coefficients

    • Use when full first-order potential flow results (e.g. from WAMIT) are available and interaction effects or short-wave loading need to be accounted for. Requires pre-processing of WAMIT results.

  • Net

    • Use for modelling nets (e.g. fish cage net panels). Provides net hydrodynamic properties and added mass coefficients. Can only be used with bar elements (no bending or torsional stiffness).

  • Loads due to vortex induced vibrations (Time domain VIV)

    • Use when time domain vortex-induced vibration loads need to be accounted for in the dynamic analysis. Supports cross-flow and in-line VIV load options.

      Pure in-line VIV is currently under development.

  • None

    • No hydrodynamic loads are applied. This can be used for testing or when hydrodynamic loads are negligible.

  • Froude-Krylov Scaling

    • An input parameter that scales the Froude-Krylov force contribution. Available for Morison’s Generalized Equation and Potential Flow only. For Potential Flow, it must be set to zero if the Froude-Krylov pressure is already included in the WAMIT results.