Andrea Colagrossi

Italian National Research Council | CNR · CNR-INM (INstitue of Marine Engineering)

The European H2020 project SLOWD is aimed to investigate the fuel sloshing damping effect to reduce the design loads on aircraft wings. Wings house the fuel tanks and are highly flexible structures that can significantly deform under gust loads. In the recent experiment by Martinez-Carrascal and González-Gutiérrez [“Experimental study of the liquid...

The smoothed particle hydrodynamics (SPH) research community has pursued simulating cavitating flows during the past decades, but so far there are no accurate and stable SPH-based cavitation models. This paper aims to present an attempt to predict cavitation phenomena within the SPH framework. To this end, an equation-of-state-based (EoSB) cavitati...

The Diffused Vortex Hydrodynamics (DVH) is a Vortex Particle Method widely validated in the last decade. This numerical approach allows cost-effective simulations of viscous flows past bodies at moderate and high Reynolds numbers, by taking into account only the rotational part of the flow field. In the present work a novel multi-resolution techniq...

The present paper investigates the planar flow past a circular cylinder for Reynolds numbers between 1000 and 10 000. The flow is studied as a dynamical system, so the present investigation is motivated by the presence of complex patterns, as the Reynolds number increases, in the force-time signals when the system goes from the periodic to the chao...

The present work is dedicated to the numerical investigation of three-dimensional sloshing flows inside a ship LNG fuel tank. Long time simulations, involving 3-hours real-time duration with realistic severe sea-state forcing, have been performed using a parallel SPH solver running for several weeks on a dedicated cluster. The adopted SPH method re...

The present work is dedicated to the numerical investigation of sloshing flows inside a ship LNG fuel tank. Long time simulations, involving 3-hours real-time duration with realistic severe sea-state forcing, have been performed using a parallel CFD solver running for several weeks on a dedicated cluster. The numerical model adopted is the Smoothed...

The present work develops an accurate and robust axisymmetric SPH method by introducing the Riemann solver into the framework of axisymmetric SPH. To reduce numerical dissipations caused by the intrinsic numerical viscosity of the Riemann solver, PVRS Riemann solver with MUSCL reconstruction is embedded into the scheme of the axisymmetric Riemann S...

The sloshing motion of a confined liquid inside a vertically moving tank is analyzed in the present series of paper. The main objective of the study is to understand the multiple resulting energy dissipation mechanisms, namely wall-liquid impacts and free surface phenomena, among others. This analysis is connected to the damping effects on the airc...

In Part I of this series [Marrone et al., Numerical study on the dissipation mechanisms in sloshing flows induced by violent and high-frequency accelerations. I. Theoretical formulation and numerical investigation, Phys. Rev. Fluids 6, 114801 (2021)], a theoretical formulation and the numerical model were developed in order to obtain a complete per...

This research was started in 2019 for the 500th anniversary of Leonardo da Vinci's death. Our Italian-French research group focused its attention on a famous drawing by da Vinci in which a water jet impacts on a pool (RCIN 912660 The Windsor Collection). This particular drawing has often been used by many fluid dynamicists as the first important do...

In two previous papers we presented an algorithm for coupling the Finite Volume (FV) method for the solution of 2D Navier–Stokes equations discretized on block structured Eulerian grids with the weakly-compressible Lagrangian Smoothed Particle Hydrodynamics (SPH) method. This coupling procedure exploits the SPH method to discretize flow regions clo...

The smoothed particle hydrodynamics (SPH) method is used in this paper to model micropolar fluids, with emphasis on their dissipation mechanisms. To this aim, a dissipation function is defined at the particle level which depends on the relative velocity between particles but also on an additional spin degree of freedom, which modifies such relative...

A dynamical system involving the decaying test of a partially filled liquid tank is analyzed in the present paper. This analysis is relevant for the design of aircraft fuel tanks, where the wings' structural dynamics are influenced by the complexity and the violence of the internal flow generated when atmospheric turbulence or gust is encountered....

In the present paper, the study of different regimes arising from the incompressible planar viscous flow past an elliptical cylinder is presented. In order to highlight the effect of the different parameters on the onset of the regimes, two different aspect ratios, 0.10 and 0.40, are considered and the angles of attack span from 0∘ to 90∘, while th...

The present work deals with some recent developments regarding the inclusion of the Large-Eddy Simulation (LES) in the weakly compressible Smoothed Particle Hydrodynamics (SPH) framework. Previously {see the work of Di Mascio et al. [Phys. Fluids 29, 4 (2017)]}, this goal was achieved by applying a Lagrangian filter to the Navier–Stokes equations f...

The behaviour of a weakly-compressible SPH scheme obtained by rewriting the Navier-Stokes equations in an arbitrary Lagrangian-Eulerian (ALE) format is studied. Differently from previous works on ALE, which generally adopt conservative variables (i.e. mass and momentum) and rely on the use of Riemann solvers inside the spatial operators, the propos...

In the present work the multi-phase SPH model presented in Grenier et al. (2009) is considered and extended through the inclusion of a diffusive term in the continuity equation. The latter based on the δ-SPH model of Antuono et al. (2012), allows to improve the evaluation of the pressure field, removing numerical noise and improving also the partic...

The study of an airfoil at low Reynolds number regime was found to be a typical problem where the inception of bifurcations leads the flow evolution from a stationary or periodic behaviour to a purely chaotic one. The present work extends the present literature where numerical investigations of the flow field past two-dimensional symmetric airfoils...

An angular momentum conservative pure bulk viscosity term for smoothed particle hydrodynamics (SPH) is proposed in the present paper. This formulation permits independent modeling of shear and bulk viscosities, which is of paramount importance for fluids with large bulk viscosity in situations where sound waves or large Mach numbers are expected. W...

In this paper, the Lagrangian particle method δ-P lus-SPH model is used to solve a series of benchmark test-cases of vortex induced vibrations (VIV). An Adaptive Particle Refinement (APR) technique is adopted to resolve correctly the boundary layer regions of the moving bodies, and to de-refine the particles that are transported far away. Furthermo...

In the present paper, a Vortex Particle Method is combined with a Boundary Element Method for the study of viscous incompressible planar flow around solid bodies. The method is based on Chorins operator splitting approach for the Navier–Stokes equations written in vorticity–velocity formulation, and consists of an advection step followed by a diffu...

The wings of large civil passenger aircrafts, which are designed to withstand the loads occurring from atmospheric gusts and turbulence to landing impacts, still demand further research. This goal will be achieved through investigating the damping effect of sloshing on the dynamics of flexible wing-like structures carrying liquid via the developmen...

The question of whether it is possible to set relevant, robust and reliable benchmarks for viscous free-surface flows with complex free-surface dynamics is investigated in this work. The proposed method for finding an answer to this question consists of selecting three conditions leading to increasing flow complexity and to simulate them using thre...

In the present work a consistent inclusion of a particle shifting technique (PST) in the weakly compressible Smoothed Particle Hydrodynamic (SPH) models is discussed. Recently, it has been shown that the use of PST can largely improve both the accuracy and the robustness of SPH models. In particular, the δ ⁺ -SPH model is a weakly-compressible SPH...

The present work addresses the evaluation by numerical simulation of the extreme loads acting on a flap-type wave energy converter. To this aim, a realistic situation is considered: an extreme wave impacting a bottom-mounted pitching device, consisting of a partly submerged flap, placed in front of a dike on the coast of Bayonne, south-west Atlanti...

This work aims to clarify some of the dissipation properties observed in the weakly compressible SPH model with artificial diffusive terms, by specifically considering the δ-SPH formulation. The main features of the δ-SPH formulation are the use of two diffusive terms added in the continuity and momentum equations in order to stabilise the scheme....

In the present study, the sudden changes of the flow field past stalled airfoils for small variations of the Reynolds number are investigated numerically. A vortex particle method has been used for the simulations in a two-dimensional framework. The most critical configurations found with this solver are verified through the comparison with the sol...

This paper presents a numerical analysis of the time behaviours of mechanical and internal fluid energies during generation, propagation and absorption of gravity waves. The analyses are performed through a Smoothed Particle Hydrodynamics (SPH) model in which the viscous and diffusive dissipations are determined through the turbulence closure model...

The violent water entry of flat plates is investigated through a Riemann-ALE SPH model. The test conditions are of interest for problems related to aircraft and helicopter emergency landing in water. Three main parameters are considered: the horizontal velocity, the approach angle (i.e. vertical to horizontal velocity ratio) and the pitch angle, α....

It is well known that the use of SPH models in simulating flow at high Reynolds numbers is limited because of the tensile instability inception in the fluid region characterized by high vorticity and negative pressure. In order to overcome this issue, the δ+-SPH scheme is modified by implementing a Tensile Instability Control (TIC). The latter cons...

The present work is dedicated to the application of the recently developed (δ+-SPH) scheme to the self-propulsive fishlike swimming hydrodynamics. In the numerical method, a particle shifting technique (PST) is implemented in the framework of δ-SPH, combining with an adaptive particle refinement (APR) which is a numerical technique adopted to refin...

The violent water entry of flat plates is investigated using a Riemann-arbitrary Eulerian-Lagrangian (ALE) smoothed particle hydrodynamics (SPH) model. The test conditions are of interest for problems related to aircraft and helicopter emergency landing in water. Three main parameters are considered: the horizontal velocity, the approach angle (i.e...

Stokes' hypothesis, the zeroing of the bulk viscosity in a Newtonian fluid, is discussed in this paper. To this aim, a continuum macroscopic fluid domain is initially modeled as a Hamiltonian system of discrete particles, for which the interparticle dissipative forces are required to be radial in order to conserve the angular momentum. The resultin...

The load assessment in water impacts problems involving complex geometries is generally a quite challenging task for numerical solvers. Indeed, the occurrence of large free-surface deformation, air cushioning and possible compressibility effects strain the standard Computational Fluid Dynamics (CFD) codes to their limits. In the present work, an en...

The Diffused Vortex Hydrodynamic (DVH) is a meshless 2D Lagrangian incompressible Particle Vortex Method. In this study the DVH will be applied to simulate viscous flows around five different bodies at Re=10,000. In order to show how the DVH method works, simulations about five different geometries will be discussed: (i) a cylinder with circular se...

In ocean engineering, the applications are usually related to a free surface which brings so many interesting physical phenomena (e.g. water waves, impacts, splashing jets, etc.). To model these complex free surface flows is a tough and challenging task for most computational fluid dynamics (CFD) solvers which work in the Eulerian framework. As a L...

The Smoothed Particle Hydrodynamics (SPH) method, often used for the modelling of the Navier–Stokes equations by a meshless Lagrangian approach, is revisited from the point of view of Large Eddy Simulation(LES). To this aim, the LES filtering procedure is recast in a Lagrangian framework by defining a filter that moves with the positions of the flu...

The present paper is dedicated to the post-processing analysis of the time pressure signals when a weakly-compressible Smoothed Particle Hydrodynamics (SPH) model is used to simulate free-surface flows. Indeed, it is well known in literature that this particle model is characterized by the occurrence of high-frequency acoustic noise making the pres...

Single-phase two-dimensional flow past a circular cylinder intersecting, or close to, a free surface at a Reynolds number of 180 is numerically investigated in this paper series using the Smoothed Particle Hydrodynamics (SPH) method. The wake behavior for Froude numbers between 0.3 and 2.0, based on the diameter, and for submergence-diameter ratios...

In the present work, the energy conservation properties of the Smoothed Particle Hydrodynamics (SPH) are investigated in the presence of fluid-solid interactions. Similarly to the fluid phase, the solid bodies are modelled through solid particles so that the whole solid-fluid domain can be described as a unique particle system. The pressure and vel...

In the present paper the study of the two-dimensional flow field past a circular cylinder for Reynolds number up to 5 · 10⁵ is addressed. A Lagrangian particle method approach has been exploited and the simulations have been performed with high spatial resolutions in order to resolve all the main vortical scales. Long simulation time evolutions hav...

The present work is dedicated to the improvement of the -SPH scheme. This is an enhanced weakly-compressible SPH model widely used in recent years thanks to its benefits to the standard SPH scheme, to its low CPU costs and to its ease of implementation. Nonetheless, the -SPH still presents some drawbacks as other SPH models. For example, in some cr...

In this work two particle methods are studied in the context of viscous flows. The first one is a Vortex Particle Method, called Diffused Vortex Hydrodynamics (DVH), recently developed to simulate complex viscous flows at medium and high Reynolds regimes. This method presents some similarities with the SPH model and its Lagrangian meshless nature,...

Flow past a circular cylinder close to a free surface at low Reynolds number is investigated numerically in this paper extending the work done in previous 2014 and 2015 OMAE papers [1, 2]. In the former, the dependence of the flow with the submergence was discussed and in the latter the flow at high Froude numbers was investigated. It was found tha...

The study of energetic free-surface flows is challenging because of the large range of interface scales involved due to multiple fragmentations and reconnections of the air-water interface with the formation of drops and bubbles. Because of their complexity the investigation of such phenomena through numerical simulation largely increased during re...

The present work is dedicated to the detection of Lagrangian Coherent Structures (LCSs) in viscous flows through the Finite-Time Lyapunov Exponents (FTLEs) which have been addressed by several works in the recent literature. Here, a novel numerical technique is presented in the context of the Smoothed Particle Hydrodynamics (SPH) models. Thanks to...