Marine hydrodynamics

RESEARCH FIELD The research field deals with several branches of problems connected with water and marine units (ships and ocean structures): 1) characterization of the sea environment, involving surface waves propagating in deep, finite and shallow waters, both in open sea and in channels, internal waves, currents and wind; 2) modeling of the marine units operating as stationary structures or as advancing/maneuvering vessels; 3) estimation of the fluid-induced body motions and/or loads and analysis of the fluid-structure interaction phenomena, also including violent features and the presence or less of incident waves. When the hydrodynamic loads cause elastic deformations of the structure which in return affect the flow evolution, hydroelasticity matters and the fluid-dynamic and structural problems must be solved as coupled. The research studies involve: free-surface and multi-phase (e.g. water, air and oil) flows, rigid and elastic bodies generally shaped with a certain degree of bluntness and slenderness and used as single or multi-body arrangements, vortex shedding and wake flows, open ocean, and sea-floor and shore effects. The experiments are considered the most reliable investigation mean, but Computational Fluid Dynamics (CFD) solvers have great potentialities and theoretical approaches can provide quick answers when simplifications can be made. A synergetic use of these three tools is desirable. RESEARCH APPLICATIONS The applications are connected with the estimation of (1) the behavior at sea of ships and offshore structures, i.e. seakeeping and station-keeping, respectively, (2) vessel maneuvering capabilities, (3) resistance and required propulsion, (4) phenomena leading to off-design conditions, e.g. added resistance and speed loss. The dynamic stability for high-speed vessels represents also an important application. The fluid-structure interactions may involve local nonlinear phenomena such as water shipping and slamming/water-entry and water-exit events, which can be responsible for important local/global consequences. In this framework, safety is an important motivation for research in this area. Implications of climate changes on safe design and operation, including new methodology to determine the impact of extreme waves on ships and other marine structures are also important applications. Finite and shallow-water studies are relevant for the actual alternative-energy devices (e.g. offshore wind turbines) and for aquaculture and oil and gas industries. In this case, nature and topography of the sea floor, wave steepening and breaking, will affect features and amplitudes of induced loads/motions on the marine units. Future installations could be made in the Arctic and in the open ocean, due to the climate changes and the need for new resources. These represent other crucial application topics