Hydroelastic interaction between ocean waves and large floating structures in the inhomogeneous ocean environment

• Main Authors: Karperaki, Angeliki, Καρπεράκη, Αγγελική
• Language: unknown
• Published: 2021
• Subjects: Υδροελαστικότητα; Μεγάλες πλωτές κατασκευές; Μέθοδος πεπερασμένων στοιχείων; Σύστημα συζευγμένων ιδιομορφών; Μείωση διάστασης; Finite element method; Coupled mode system; Dimensionality reduction; Hydroelasticity; Large floating structures; Ice Shelf; Sea ice
• Online Access: https://dspace.lib.ntua.gr/xmlui/handle/123456789/53190; https://doi.org/10.26240/heal.ntua.20888

Interaction of waves with Very Large Floating Structures (VLFS) and sea ice formations present similarities permitting a common mathematical treatment and numerical modelling. Wave-induced structural response and its underlying effect on the hydrodynamic field are fundamental to the in-depth understanding of physical processes like ice shelf calving as well as the design of marine structures operating nearshore. The common features of the aforementioned systems are: (a) their low bending rigidity, (b) their inherently complex geometries and material inhomogeneity and (c) their extent over large horizontal domains, dictating the need to address the effects of bathymetric variations. The common ground allows for the development of joint computational tools for the treatment of the above coupled wave-structure-seabed interaction problems. Intricacies lay on the very same features, namely the large horizontal domains along with geometric and material inhomogeneity. In this work a novel methodology is proposed based on finite elements, in conjunction with coupled-mode system formulation, which is derived by appropriate local-mode representations of the vertical structure of the wave field. Confined in the linear regime, potential theory is employed. The floating body is assumed to be thin in the vertical direction within the limits of reduced elastic plate models. Depending on the structure slenderness and the excitation wavelength-to-plate thickness ratio, the structure is modelled using either Classical Thin or Reissner-Mindlin Plate theory to account for first order shear deformation effects. The wave field is decomposed in the propagating component over the variable bathymetry (in the absense of the body) and the diffraction and radiation parts both due to the rigid motions and the elastic plate deflection. An in vacuo modal expansion for the plate deflection is employed to partially decouple the hydrodynamics from structural mechanics. The employed decomposition allows for the formulation of a propagating wave ...