Fluid Structure Interaction of Buoyant Bodies with Free Surface Flows: Computational Modelling and Experimental Validation

Abstract

In this paper we present a computational model for the fluid structure interaction of a buoyant rigid body immersed in a free surface flow. The presence of a free surface and its interaction with buoyant bodies make the problem very challenging. In fact, with light (compared to the fluid) or very flexible structures, fluid forces generate large displacements or accelerations of the solid and this enhances the artificial added mass effect. Such a problem is relevant in particular in naval and ocean engineering and for wave energy harvesting, where a correct prediction of the hydrodynamic loading exerted by the fluid on buoyant structures is crucial. To this aim, we develop and validate a tightly coupled algorithm that is able to deal with large structural displacement and impulsive acceleration typical, for instance, of water entry problems. The free surface flow is modeled through the volume of fluid model, the finite volume method is utilized is to discretize the flow and solid motion is described by the Newton-Euler equations. Fluid structure interaction is modeled through a Dirichlet-Newmann partitioned approach and tight coupling is achieved by utilizing a fixed-point iterative procedure. As most experimental data available in literature are limited to the first instants after the water impact, for larger hydrodynamic forces, we specifically designed a set of dedicated experiments on the water impact of a buoyant cylinder, to validate the proposed methodology in a more general framework. Finally, to demonstrate that the proposed numerical model could be used for a wide range of engineering problems related to FSI in multiphase flows, we tested the proposed numerical model for the simulation of a floating body.

Vulnerability of Hydraulic Constructions in Flood-Prone Agricultural Areas

“…In fact, the MCA could be applied to our case study if we had proper data to calibrate the model. Moreover, we are currently investigating the possible integration of detailed hydraulic simulations [57][58][59][60][61] instead of one-dimensional ones for particularly complex circumstances, thus improving the effectiveness of the methodology. In particular, Tables A1 and A2 report the number of bridges and road embankments at different levels of freeboard for an RT = 50 and RT = 200 and corresponding vulnerability levels.…”

Wave Force Characteristics and Stability of Detached Breakwaters Consisting of Open Cell Caissons Interlocked via Crushed Stones

“…During the experiment, a sampling rate of 600 Hz was set to measure water level fluctuations, wave pressures, and displacements. In generating impulsive pressure by breaking waves, it should be set to be 1 kHz or higher [20][21][22], but our sampling rate is sufficient to acquire data to qualitatively confirm the occurrence of impulsive pressure in this experiment [23].…”

Analysis of Deformation in an Aluminium Hull Impacting Water Free Surface

“…Bodies' impact on free water surface represents an interesting and widely investigated topic in the literature, in particular in the case of cylindrical bodies [20][21][22][23][24][25][26][27][28][29][30] and wedges [31,32]. These works are mainly focused on fluid dynamics, on the evolution of the free surface and the pileup [26][27][28][29] through both numerical and experimental analyses [21,24,32]; moreover, some works concern fluid-structure interaction considering both rigid and flexible structures and several levels of complexity, from simple systems (in terms of structure geometry and fluid-structure interaction) [23,25,31] to advanced applications concerning sea loads on simple geometries [22] or complex geometries [20,30]. Here the proposed reconstruction methodology [6] is applied to a three-dimensional aluminium wedge modified as a ship hull.…”