# Vincenzo ArmenioUniversity of Trieste | UNITS · Department of Engineering and Architecture

Vincenzo Armenio

Ph.D., Professor

## About

142

Publications

26,111

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2,664

Citations

Citations since 2017

Introduction

Vincenzo Armenio currently works at the Department of Engineering and Architecture, University of Trieste. Vincenzo does research in Environmental Engineering, Industrial Engineering and Civil Engineering. Their current project is 'Rotating RBC'.

## Publications

Publications (142)

In the present work, we develop a new methodology to investigate the propagation of acoustic noise originating from a naval propeller, in a bounded marine environment. The propagation in a realistic environment is achieved by coupling the Ffowcs-Williams and Hawkings (FW-H) equation with the acoustic wave equation, overcoming some intrinsic limitat...

In the present work we perform the numerical characterization of the hydrodynamic and the hydroacoustic field of a notional submarine geometry (the BB2 submarine). Starting from a model-scale CFD simulation, the full scale acoustic signature of the submarine is derived. We use large eddy simulation with a wall-layer model and perform laboratory-sca...

The acoustic analogy is adopted to characterise the signature of a seven-bladed submarine propeller, relying on a high-fidelity large-eddy simulation, performed on a computational grid consisting of 840 million points. Results demonstrate that the nonlinear terms of the Ffowcs-Williams and Hawkings equation quickly become dominant moving away from...

The need to understand how complex acoustic sources propagate noise in a realistic environment is of growing interest. In this work, we propose a numerical model for the simulation of noise generated by sources with directivity and propagating in ocean waveguides. The numerical model solves the wave equation for the acoustic pressure in the physica...

We present results of numerical simulations of a stratified reservoir with a three-layer stratification, subject to an oscillating surface shear stress. We investigate the effect of sloped endwalls on mixing and internal wave adjustment to forcing within the basin, for three different periods of forcing. The simulations are carried out at a laborat...

We perform a scaling analysis of the terms composing the Ffowcs-Williams and Hawkings (FWH) equation, which rules the propagation of noise generated by a rigid body in motion. Our analysis extends the seminal work of Lighthill ( Proc. R. Soc. Lond. A, vol. 211, 1952, pp. 564–587) and the dimensional analysis of classical sources (monopole, dipole a...

Cavitation is often simulated using a mixture model, which considers the transport of an active scalar, namely the vapor fraction αv. Source and sink terms of the transport equation of αv, namely vaporization and condensation terms, rule the dynamics of the cavity and are described through different models. These models contain empirical coefficien...

Scaling parameters governing the physics of two-phase flow turbulence are presented, in particular for the study of coupled Poiseuille–Couette flows where waves are well under the capillary regime. Different approaches can be followed to either simplify the analysis of the results or computational requirements to run such case. Such simplification...

One-dimensional models of exchange flows driven by horizontal density gradients are well known for performing poorly in situations with weak turbulent mixing. The main issue with these models is that the horizontal density gradient is usually imposed as a constant, leading to non-physically high stratification known as runaway stratification. Here,...

The problem of turbulent Couette flow driven by a statistically steady external wind is studied in the framework of spatially filtered Navier–Stokes equations. The phenomenon of wind-driven flow of water is represented by a layer of air modeled as Poiseuille flow (air sub-domain), coupled to a layer of water modeled as Couette flow (water sub-domai...

The existence and properties of the logarithmic layer in a turbulent streamwise oscillating flow are investigated through direct numerical simulations and wall-resolved large-eddy simulations. The phase dependence of the von Kármán constant and the logarithmic layer intercept is explored for different values of the Reynolds number and the depth-rat...

We performed high-resolution numerical simulations of a turbulent flow driven by an oscillating uniform pressure gradient. The purpose was to investigate the influence of a reduced water depth h on the structure and dynamics of the turbulent boundary layer and the transition towards a fully turbulent flow. The study is motivated by applications of...

In the present paper, we study the hydrodynamic noise generated by a ship propeller in open sea conditions. We use Large Eddy Simulation for the hydrodynamic field whereas the acoustic field is reconstructed by applying the advective form of the Ffowcs-Williams and Hawkings equation. A dynamic Lagrangian model is adopted for the closure of the subg...

We validate and test two algorithms for the time integration of the Boussinesq form of the Navier—Stokes equations within the Large Eddy Simulation (LES) methodology for turbulent flows. The algorithms are implemented in the OpenFOAM framework. From one side, we have implemented an energy-conserving incremental-pressure Runge–Kutta (RK4) projection...

In the present paper we study buoyant (plume) and non-buoyant (jet) fluid injection in a neutrally stratified uniform cross-flow. Both cases are of practical importance in environmental fluid mechanics. The study is carried out numerically, using highly resolved large-eddy simulation in conjunction with the Lagrangian dynamic sub-grid scale model f...

Large-eddy simulations of thermal convection are presented and discussed for a cube with rough horizontal surfaces. Two types of roughness are considered: uniformly placed pyramids, and grooves aligned parallel to one set of sidewalls. The Rayleigh number is 10 8 , the Prandtl number 0.7, and the aspect ratio 1, as in a previous study [N. Foroozani...

A major threat for marine and coastal environment comes from oil spill accidents. Such events have a great impact on both the ecosystem and on the economy, and the risk increases over time due to increasing ship traffic in many sensitive areas. In recent years, numerical simulation of oil spills has become an affordable tool for the analysis of the...

The present study focuses on the evaluation of the impact of marine stable stratification on turbine performance and wake characteristics. Stratification is usually present in regions where marine turbines are installed; this is the case of estuarine basins and shelf seas. Stratification influences the turbine efficiency and rotor wake development;...

The objective of the present work is to study wake dynamics behind a surface-mounted circular cylinder immersed between two highly stratified fluids in the crossflow, by performing LES. The focus is to evaluate the degree of interference and interaction caused by the presence of obstacles and of the air-water interface over incoming turbulent bound...

This book gathers the proceedings of the 11th workshop on Direct and Large Eddy Simulation (DLES), which was held in Pisa, Italy in May 2017. The event focused on modern techniques for simulating turbulent flows based on the partial or full resolution of the instantaneous turbulent flow structures, as Direct Numerical Simulation (DNS), Large-Eddy S...

Unconfined three-dimensional gravity currents generated by lock exchange using a small dividing gate in a sufficiently large tank are investigated by means of large eddy simulations under the Boussinesq approximation, with Grashof numbers varying over five orders of magnitudes. The study shows that, after an initial transient, the flow can be separ...

In nature and in many industrial applications, the boundary of a channel flow is made of solid particles which form a porous wall, so that there is a mutual influence between the free flow and the subsurface flow developing inside the pores. While the influence of the porous wall on the free flow has been well studied, less well characterized is th...

The flow around ship over-structures is characterized by both separation phenomena with recirculation regions at high Reynolds number, and the fast ejection of hot smokes from chimneys. These two features are of the utmost importance for two linked goals in the ship design, namely the aerodynamic drag reduction and the preservations of passengers c...

In the present work a hybrid methodology is used to evaluate the hydrodynamic noise generated by a marine propeller in open sea condition. The hydrodynamic field is computed using Large Eddy simulation under the assumption of incompressible flow field; the acoustic field is reconstructed by applying the advective Ffowcs Williams and Hawkings equati...

A large-eddy simulation of a counter-current gas–liquid flow is performed. At the flat interface where the different fluids meet, continuity of momentum and momentum fluxes are enforced following the work of Lombardi et al. [Direct numerical simulation of near-interface turbulence in coupled gas-liquid flow. Phys Fluids. 1996;8(6):1643–1665]. The i...

Large Eddy simulations of lock-exchange gravity currents propagating over a mobile reach are presented. The numerical setting allows to investigate the sediment pick up induced by the currents and to study the underlying mechanisms leading to sediment entrainment for different Grashof numbers and grain sizes. First, the velocity field and the bed s...

Turbulent Rayleigh-Bénard convection (RBC) in a fluid heated from below and cooled from above is a challenging problem in nonlinear physics, with many important applications in natural and engineering systems. Because of the complexity of the governing equations, analytical progress in understanding convection has been slow, and laboratory experime...

This book addresses nearly all aspects of the state of the art in LES & DNS of turbulent flows, ranging from flows in biological systems and the environment to external aerodynamics, domestic and centralized energy production, combustion, propulsion as well as applications of industrial interest. Following the advances in increased computational po...

Over the years, large eddy simulation (LES) has emerged as a tool to study problems in fluid mechanics characterized by complex physics and geometry. Among these, attention has been paid to studying problems of relevance in hydraulics and environmental fluid mechanics. For many years, LES has been used as an underresolved, or coarse, direct numeric...

We investigate wind-driven circulation in a peri-alpine lake (Lake Ledro - Italy) using LES-COAST. Lake Ledro is interesting because its own dimensions are suited for LES and it is surrounded by complex orography, affecting wind distribution. We consider the winter condition when stratification is nearly absent. Two types of time-varying wind stres...

Lock-release gravity currents flowing up a slope are investigated by Large Eddy Simulations. The angle between the bottom boundary and the horizontal direction, θ, and the aspect ratio of the initial volume of dense fluid in the lock, R, are varied. The mean flow is analysed and both density and velocity fields reveal the presence of a backward flo...

A parametric investigation of radiative heat transfer is carried out, including the effects of conjugate heat transfer between fluid and solid media. The thermal radiation is simulated using the -model. The numerical model and the thermal coupling strategy, suitable for a transient solver, is described. Such numerical coupling requires that the rad...

Large-eddy simulations of turbulent Rayleigh-Bénard convection were conducted for a fluid of Prandtl number Pr=0.7 confined in a cube, for Rayleigh numbers of 106 and 108. The model solves the unsteady Navier-Stokes equations under the Boussinesq approximation, using a dynamic Smagorinsky model with a Lagrangian averaging technique for the subgrid...

In the present paper we propose an improved Nihoul’s model which accounts for the main forces acting on oil slick and ruling its spreading and transport in the first tens of hours after the spill. In the original model, Nihoul considered the Coriolis force to be negligible; we re-formulate the Nihoul’s analysis including the Coriolis force in the m...

Over the last decades, increasing interest has been paid to environmental fluid mechanics (EFM), in relation to land reclamation and the improvement of the quality of air and water on Earth. The continuous increase of the computer performance, in terms of data storage and CPU time, is making more attractive the use of numerical techniques which, so...

Density currents are a ubiquitous phenomenon caused by natural events or anthropogenic activities, and play an important role in the global sediment cycle; they are agents of long distance sediment transport in lakes, seas and oceans. Density gradients induced by salinity, temperature differences, or by the presence of suspended material are all po...

Currently, Wall Functions (WF) work well under specific conditions, mostly exhibit drawbacks specially in flows with separation beyond curvatures. In this work, we propose a more general WF which works well in attached and detached flows, in presence and absence of Immersed Boundaries (IB). First we modified an equilibrium stress WF for boundary-fi...

The present contribution aims to develop a numerical model to accurately represent the mentioned phenomena. A Large-Eddy Simulation (LES) methodology is used, where the Lagrangian dynamic Sub-Grid Scale (SGS) model is adopted to determine the SGS viscosity. To dynamically compute the temperature and vapour SGS diffusivity the same approach is follo...

The evaporation process of a plate in an enclosure is investigated numerically using large-eddy simulations. The heat exchange between fluid and solid media is reproduced, along with the evaporation/condensation of water film onto the solid surfaces. A preliminary steady state case and subsequent transitory cases (performed changing the plate mater...

The results and the main contents presented in this document, have been reported in the journal paper: Carlo Cintolesi, Hakan Nilsson, Andrea Petronio, Vincenzo Armenio. ”Numerical a simulation of conjugate heat transfer and surface radiative heat transfer using the P1 thermal radiation model: parametric study in benchmark cases”. Submitted to Int....

Thermal radiation rules, or strongly influences, many different environmental and industrial systems. A reliable numerical simulation cannot neglect radiative heat transfer within the fluid medium, along with the thermal interaction between fluid and the surrounding solids, due to surface heat transfer by conduction and radiation. Indeed, the tempe...

Entrainment and mixing in lock-exchange gravity currents are investigated by large eddy simulations. Nine cases are analysed, varying the initial excess density driving the motion and the aspect ratio r of the initial water depth to the lock length. Laboratory experiments are also performed and a fair agreement between numerical simulations and mea...

Lock-exchange gravity currents propagating up a slope are investigated by large eddy simulations, focusing on the entrainment and mixing processes occurring between the dense current and the ambient fluid. Relevant parameters, such as the aspect ratio of the initial volume of dense fluid in the lock R, the angle between the bottom boundary and the...

Simulation of detached flows using OpenFOAM, comparing RANS and LES methodology on benchamark cases

A new small drifter prototype for measuring current immediately below the free surface in a water basin is proposed in this paper. The drifter dimensions make it useful for shallow water applications. The drifter transmits its GPS location via GSM phone network. The drifter was used to study the trajectory of the surface current in the Muggia bay,...

Massive flow separation is ubiquitous in industrial applications, ruling drag and hydro-dynamic noise. In spite of considerable efforts, its numerical prediction still represents a challenge for CFD models in use in engineering. Aside commercial software, over the latter years the opensource software OpenFOAM R (OF) has emerged as a valid tool for...

Turbulent natural convection in enclosure is a paradigmatic case for wide class of processes of great interest for industrial and environmental problems. The solid-fluid thermal interaction, the anisotropy of the turbulence intensity in the flow field along with the transient nature of heat transfer processes, pose challenges regarding the numerica...

Simulation of turbulent buoyant flow with boundaries heat exchange

Large-eddy simulations (LES) of oscillating turbulent boundary layers, over a rippled bed, subjected to frame rotation are presented. This flow is archetypal of a bottom-ocean, tidally driven boundary layer developing over sand dunes. A forcing-type immersed boundary method (IBM) is used to represent the solid bed and the filtered structure functio...

In the present paper numerical simulations are used to investigate suspended sediment transport and its effect on the dynamics of the turbulent boundary layer. We use an Euler-Euler methodology based on single-phase approach. Large eddy simulation is employed to resolve the large scales of motion, whereas the contribution of the small scales is par...

We perform large-eddy simulations of turbulent convection in a cubic cell for Rayleigh numbers, Ra, between 10^{6} and 10^{10} and the molecular Prandtl number, Pr=0.7. The simulations were carried out using a second-order-accurate finite-difference method in which subgrid-scale fluxes of momentum and heat were both parametrized using a Lagrangian...

In the present paper, we use numerical simulation to investigate currents, mixing and water renewal in Barcelona harbour under typical conditions of wind forcing for the winter season. This site is of particular importance due to the interplay between touristic and commercial activities, requiring detailed and high-definition studies of water quali...

Mathematical models of sediment transport usually assume the sediment particles as passive tracer and neglect the feedback effect of sediment resuspension on near-wall momentum transport. In the present research we attempt to quantify the above mentioned effect with the aim of gaining better description of sediment-turbulence interaction. We carry...

Three-dimensional Large Eddy Simulations and laboratory experiments of lock exchange gravity currents propagating on up-sloping boundaries are presented. Different sloping angles were tested, while all the other parameters were fixed. The LES reproduce the same domain as the laboratory experiments by a very high resolution computational grid. A ver...

Particle dispersion in a stratified bottom Ekman layer is studied by direct numerical simulation. Neutral, stable and unstable stratifications are considered. The stable stratification tends both to suppress the turbulence and to reduce the boundary layer thickness, while the opposite is observed for the unstable case. Therefore stable stratificati...

Particle dispersion in a stratified bottom Ekman layer is studied by direct numerical simulation. Neutral, stable and unstable stratifications are considered. The stable stratification tends both to suppress the turbulence and to reduce the boundary layer thickness, while the opposite is observed for the unstable case. Therefore stable stratificati...

In the present paper a state-of-the-art large eddy simulation model
(LES-COAST), suited for the analysis of water circulation and mixing in
closed or semi-closed areas, is presented and applied to the study of
the hydrodynamic characteristics of the Muggia bay, the industrial
harbor of the city of Trieste, Italy. The model solves the
non-hydrostati...

The problem of pollutant dispersion is a crucial issue for life quality in urban areas.

In the present paper turbulent mixing in the Stokes–Ekman bottom boundary layer is investigated analytically and by wall-resolving large-eddy simulations (LES). The analytical solution shows that when the Rossby number oscillation and rotation interact with each other, this gives rise to a thickening of the boundary layer compared with the purely o...

Prediction of pollutant dispersion in urban area is of crucial importance to assess quality of life of populations. At urban scales, local phenomena take place, governed by the building canopy, together with large scale motion driven by vertical stratification, air humidity and heat sources created in the canopy. This situation requires up-to-date...

The scope of this paper is to analyze the performance of wall-layer model Large Eddy Simulation (WLES) in the prediction of flow separation under stable stratification. This is a fundamental problem of practical importance both in industrial and in environmental applications. We consider turbulent flow in a plane asymmetric diffuser because this si...

In environmental flows where the Reynolds numbers are very high it is not possible to solve directly the near-wall region because of the still-limited computer power. Furthermore, the presence of irregular wall-roughness in practical high Reynolds flows would make the direct resolution of the near wall viscous layer somewhat useless. When using Lar...

Local scour phenomena around bridge abutments and piers can induce the collapse of hydraulic structures (Cardoso and Bettess, 1999). Understanding of the erosion process is required for the a-priori estimation of the scour-hole geometry. The problem of local erosion is particularly difficult since a complete modeling of the process needs to take in...

The interaction of droplets that undergo phase transition with a turbulent flow is encountered in many areas of engineering and atmospheric science as described in (Lanotte et al., 2008). In the context of cloud physics the evaporation and condensation of water vapor from and to the droplets is the governing process for the growth of the droplets f...

The channel ﬂow subjected to a wind stress at the free surface and an oscillating pressure gradient is investigated using large-eddy simulations. The orientation of the surface stress is parallel with the oscillating pressure gradient and a purely pulsating mean ﬂow develops. The Reynolds number is typically Re$_\omega$ = 10^6 and the Keulegan–Carp...