VERNENGO G.

Three-dimensional effects induced by dimensional ratios on the gap resonances happening in twin hull vessels oscillating in forced vertical motion have been analyzed. They can lead to relevant consequences, such as the amplification of the inner radiated waves or the generation of standing waves in between the demi-hulls, that can have a direct...

Small Waterplane Area Twin Hulls (SWATHs) are known to have superior seakeeping performance but higher resistance compared to equivalent catamarans or mono-hulls. A way to improve their resistance characteristics is to use unconventional hull forms parametrically defined and optimized by CFD methods. This study builds on previous SWATH...

The engineering design of a three dimensional submerged hydrofoil operating at very high speeds is obtained leveraging a Differential Evolution (DE) approach. The final goal is to identify the optimal load distribution over the span of a super-cavitating hydrofoil by using a design by optimization approach driven by hydrodynamic analysis of...

A Simulation Based Design Optimization method for marine propellers design using a two-fidelity levels metamodel for global design space exploration and optimization is presented. Response surfaces are built using the co-Kriging approximation, i.e. a multi-output Gaussian process that combines large low-fidelity dataset with few, costly,...

The interaction of the free surface with either lifting and non lifting, submerged, bodies moving beneath it is of primary interest in naval architecture. Indeed, there are many examples of possible applications such as rudders, stabilizer fins, hydrofoils among the others. The hydrodynamic problem of a submerged lifting body moving close to a...

Achieving a reliable and accurate numerical prediction of the self-propulsion performance of a ship is still an open problem that poses some relevant issues. Several CFD methods, ranging from boundary element methods (BEM) to higher-fidelity viscous Reynolds averaged Navier–Stokes (RANS) based solvers, can be used to accurately analyze the...

We construct a multi-fidelity framework for statistical learning and global optimization that is capable of effectively synthesizing seakeeping predictions having two different levels of modeling fidelity, namely a strip theory and a boundary element method based on potential flow assumption. The objective of this work is to demonstrate that...

In the international regulation framework, the energy-efficient operation of ships is becoming standard. In this respect, restrictions on new construction appear to encourage improvement to existing vessels often equipped with outdated technologies. One of the relevant aspects of propulsion plant design and fleet management is the propulsion...

We propose a Simulation-Based Design Optimization (SBDO) approach for the design of an Energy Saving Device (ESD) based on the Wake Equalizing Duct (WED) concept. Pre-Ducts, like Wake Equalizing Ducts, reduce the wake losses, improve the propeller-hull interaction and generate an additional thrust. An integrated design approach, relying on a...

A computational framework for hydrodynamic shape optimization of complex ship hull form is proposed and applied to improve the calm water performance of the KRISO Container Ship (KCS). The framework relies on three key features: a novel shape morphing method based on a combination of subdivision surfaces and free form deformations, a robust...

The representation and the variation of hull shapes are two challenging problems in naval architecture due to the complexity of the geometry and to the need to ensure the fairness of the surfaces. Conventional CAD techniques are widely used to accurately describe the hull shape. However, they are rather complex to be easily used to generate...

This paper presents the results of the hydrodynamic optimization of a large yacht concept design that is meant to be used as a reference for future buildings. The optimization framework is used to improve the calm water resistance performance of a generic baseline design while satisfying a set of geometrical constraints. The shape of the hull...

The sensitivity of ship stability performance in waves to geometric variation has been investigated by means of a simulation-based design framework. The study was devoted to assess the influence of hull geometry variations on some stability failure modes, namely, parametric roll (PR) and pure loss of stability (PLS). The application has been...

The estimation of wave breaking and run-up on sloped beaches is a relevant issue in different coastal engineering applications. The present study stresses on the capabilities of a Smoothed Particle Hydrodynamics (SPH) solver, with optimal numerical and physical parameters, to accurately simulate the complex flow field in the surf zone and...

Simulation-driven shape optimisation (SDSO) of marine propellers is often obstructed by high-dimensional design spaces stemming from its complex geometry and baseline parameterisation, which leads to the notorious curse of dimensionality. In this study, we propose using the shape-supervised dimension reduction (SSDR) approach to expedite the...

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A method for the morphing of surface/volume meshes suitable to be used in hydrodynamic shape optimization is proposed. Built in the OpenFOAM environment, it relies on a Laplace equation that propagates the modifications of the surface boundaries, realized by applying a free-form deformation to a subdivision surface description of the geometry,...

The hydrodynamics of surface piercing struts and pile-like structures in general presents some very complex fluid dynamics phenomena that are worth investigating. Among them there are the forward wave pile-up at stagnation, the wave breaking with flow reversal like that observed in Bidone-type hydraulic jumps, flow separation caused by...

Submarines bring many interesting hydrodynamic challenges that need to be properly addressed to provide precise and reliable information about their performance. Hydrodynamic performance must be evaluated at least in two main operating conditions, namely when it is deeply submerged and at snorkel depth. There are relevant differences in terms...