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December 7, 2011
The Center for Ocean Engineering Presents "Design and Hydrodynamics of High Speed Ships" by Prof. Stefano Brizzolara
Date: Thursday, December 8, 2011
Refreshments will be provided before the seminar
Examples will include: semi-displacement, Deep-V Monohulls designed for the first series of largest-ever fast ferries (140m, 40+ knots), the same hull type currently used for the LCS-1 series of US Navy ships; multi-hulls such as trimaran and unconventional SWATH (Small Waterplane Area Twin Hull) vessels with hull forms that noticeably reduce drag at high speeds; stepped planing hulls with partial ventilation of the bottom at the highest Froude numbers; and the most advanced hybrid vessels, dynamically supported by super-cavitating hydrofoils and capable of speeds in excess of 100 knots. Certain hydrodynamic design aspects of the propellers or impellers used on these vessels, where the correct modeling of unsteady cavitation is a primary issue, will also be discussed.
For each example presented, the chief hydrodynamic peculiarities of the design will be described and the numerical models used to solve the main design problems. Methods presented will range from steady and unsteady potential flow panel methods with thin boundary layer corrections and non-linear cavitation effects, to finite volume solvers of the unsteady Reynolds Averaged Navier-Stokes Equations with volume of fluid multi-phase and cavitation models to deal with two or three phase flows (air/water/vapor). Recently, potential flow methods have been integrated into numerical shape optimization procedures in combination with efficient multi-objective minimization algorithms and smart parametric 3D geometry representations for optimization of the automatic hull or propeller. The fully turbulent viscous solvers have been intensively tested and validated for various planing and displacement hull forms in stationary conditions, while there are ongoing developments, particularly regarding combined cavitation/ventilation of surface-piercing hydrofoils or propellers and viscous simulations of vessels motions in waves.
He founded and currently coordinates the Marine CFD Group, a research team devoted to the development, application and validation of CFD methods for Marine hydrodynamics, ranging from BEM, RANSE and SPH applied to hydrodynamics of propellers, resistance propulsion fast ship hulls, cavitation and seakeeping. He also contributes to several EU framework research projects, the Maritime Industry, the Italian MoD and the Office of Naval Research of the US Navy, dealing with hydrodynamics of advanced vessel and propulsion systems. Past experience includes: experimental research on propellers and hydrofoils at the cavitation tunnel of the Italian Navy in Rome; senior designer of navy ships and propellers in the hydrodynamic design office of Fincantieri Navy Ship Business Unit (Genoa, Italy). He is author of more than 80 scientific papers and holder of three patents.