Costantino Manes

Costantino Manes
Politecnico di Torino | polito · DIATI - Department of Environment, Land and Infrastructure Engineering

About

75
Publications
23,464
Reads
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1,695
Citations
Introduction
Environmental and Industrial Fluid Mechanics
Additional affiliations
October 2011 - November 2015
University of Southampton
Position
  • Lecturer

Publications

Publications (75)
Article
Full-text available
Ureteric stents are clinically deployed to restore urinary drainage in the presence of ureteric occlusions. They consist of a hollow tube with multiple side-holes that enhance urinary drainage. The stent surface is often subject to encrustation (induced by crystals-forming bacteria such as Proteus mirabilis) or particle accumulation, which may comp...
Article
Full-text available
Flux reduction induced by fouling is arguably the most adverse phenomenon in membrane-based separation systems. In this respect, many laboratory-scale filtration studies have shown that an appropriate use of hydrodynamic perturbations can improve both performance and durability of the membrane; however, to fully understand and hence appropriately e...
Article
This paper provides insights into processes governing oil-mist filtration in coalescing filters. In particular, it resolves an apparent inconsistency between different published studies regarding the occurrence (or not) of internal gravity-induced flows. As a result of this, it also clarifies whether in industrially-relevant scenarios such as those...
Article
This paper presents some results coming from a linear stability analysis of turbulent depth-averaged open-channel flows (OCFs) with secondary currents. The aim was to identify plausible mechanisms underpinning the formation of large-scale turbulence structures, which are commonly referred to as large-scale motions (LSMs) and very-large-scale motion...
Article
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This work investigates how turbulence in open-channel flows is altered by the passage of surface waves by using experimental data collected with laboratory tests in a large-scale flume facility, wherein waves followed a current. Flow velocity data were measured with a laser Doppler anemometer and used to compute profiles of mean velocity and Reynol...
Article
Empirical formulas describing the Darcy-Weisbach friction factor remain indispensable for applications in sciences and engineering dealing with turbulent flows. Despite their practical significance, these formulas have remained without theoretical interpretation for many decades. To close this knowledge gap, much research has been devoted to the de...
Article
Previous research has shown that local scour at bridge piers is severely increased by the accumulation of woody debris around piers. However, due to the unavailability of accurate information regarding the characteristics of formed debris jams, the shape and dimensions of accumulations tested in previous laboratory experiments had to be assumed. Th...
Article
Pore-scale CFD simulations of liquid aerosol filtration in coalescing fibrous filters are currently limited by severe computational constraints. In this paper, we present a new multiphase multicomponent framework for modelling such dynamic filtration process at the Darcy-scale. Moving from the pore- to the Darcy-scale allows for significant reducti...
Article
Several studies have investigated the dynamics of a single spherical bubble at rest under a nonstationary pressure forcing. However, attention has almost always been focused on periodic pressure oscillations, neglecting the case of stochastic forcing. This fact is quite surprising, as random pressure fluctuations are widespread in many applications...
Conference Paper
Full-text available
The scaling of Large-and Very-Large-Scale Motions (LSMs and VLSMs) is studied in non-uniform smooth-bed open-channel flows. Results indicate that LSMs scale with the flow depth whereas the size of VLSMs is dictated by the aspect ratio, namely the ratio between channel width and flow depth.
Conference Paper
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The interaction between waves and wall turbulence is studied in a smooth-bed open-channel flume where waves following a current can be generated. Herein, for the first time in combined wave-current flows, the simultaneous inner-outer scaling of the vertical profiles of the mean longitudinal velocity is presented. This simultaneous scaling indicates...
Article
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Systematic experiments on European eel (Anguilla anguilla) in their juvenile, early life stage (glass eel), were conducted to provide new insights on the fish swimming performance and propose a framework of analysis to design swimming-performance experiments for bottom-dwelling fish. In particular, we coupled experimental and computational fluid dy...
Article
Spatial patterns in moving fish shoals originate from social interactions and are driven by factors that benefit individuals, such as predator avoidance or reduced energy expenditure. How shoaling is influenced by the presence and absence of a flow field is only partially understood. Adopting a reductionist approach, time spent shoaling, shoal stru...
Article
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This paper investigates the existence and scaling of the so-called large-scale and very-large-scale motions (LSMs and VLSMs) in non-uniform turbulent open-channel flows developing over a smooth bed in a laboratory flume. A laser Doppler anemometry system was employed to measure vertical profiles of longitudinal and bed-normal velocity statistics ov...
Article
In the last five decades much research has been devoted to the development of predictive formulae to quantify the maximum local-scour depth developing around hydraulic structures (e.g bridge piers). Owing to the complexity of the problem, most of the proposed formulae were developed on empirical grounds, which made them susceptible to scale issues....
Article
The properties of the wake generated by a porous body fully immersed in a turbulent boundary layer are experimentally assessed. The body consists of an array of cylinders, with diameter d, covering a circular patch of diameter D. For fixed d and D, by increasing the number of cylinders, Nc, within the patch, the wake properties are systematically t...
Conference Paper
Full-text available
KEY POINTS  Artificial Vegetation Patches (VP) can be used for the design of fish passes.  The drag coefficient of VP depends on the patch solidity (SVF).  The drag coefficient vs SVF is explained by bleeding effects.  RANS-based CFD allows for a satisfactory prediction of VP drag.
Article
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Hydrodynamic Cavitation (HC) is considered as a promising water-disinfection technique. Due to the enormous complexity of the physical and chemical processes at play, research on HC reactors is usually carried out following an empirical approach. Surprisingly, past experimental studies have never been designed on dimensional-analysis principles, wh...
Article
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A novel scanning technique using a rotating-head sonar profiler attached to a slider mechanism is presented as a means to directly measure the complex erosion and deposition features of local scour holes developing in clear-water conditions around vertical cylinders mimicking bridge piers. Extensive validation shows that the method produces high-de...
Conference Paper
Full-text available
Bimodal distribution of the streamwise velocity pre-multiplied spectra in canonical turbulent flows (pipe, channel and boundary layer flow) is well documented in the literature. The two peaks of this distribution are associated with eddies of a defined size and they are called Large-Scale Motion (LSM) and Very-Large-Scale Motion (VLSM). These eddy...
Article
The apparent random swirling motion of water is labeled “turbulence,” which is a pervasive state of the flow in many hydrological and hydraulic transport phenomena. Water flow in a turbulent state can be described by the momentum conservation equations known as the Navier–Stokes (NS) equations. Solving these equations numerically or in some approxi...
Conference Paper
Full-text available
Local scour represents the erosion process that occurs at the base of hydraulic structures overlying sediment beds. Horseshoe vortices forming at the bed-structure junction are the main responsible for sediment removal and dictate erosion rates as well as the maximum erosion depth resulting from a significant flow event. In steady-flow conditions t...
Conference Paper
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The scaling results developed by Manes and Brocchini (2015) for local scour around bridge piers are herein tested for the case of vertical wall bridge abutments.
Article
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Purpose of Review. There are three technological parameters that play a key role on the performance of an ideal stent. These are its material, design and surface coating. This article highlights some fundamental developments that took place in these three areas of stent’s technology, in order to contribute to the identification of an ideal stent. R...
Article
The measurement of methane emissions from landfills is important to the understanding of landfills’ contribution to greenhouse gas emissions. The Tracer Dispersion Method (TDM) is becoming widely accepted as a technique, which allows landfill emissions to be quantified accurately provided that measurements are taken where the plumes of a released t...
Article
Scouring at the base of bridge piers is the major cause of bridge collapses worldwide. Computing the scour risk of bridge foundations is therefore key for a correct management and allocation of resources for maintenance and scour mitigation works. Existing risk-assessment models compute the vulnerability of bridge foundations to scour by comparing...
Article
Full-text available
Introduction. An ideal stent would offer simple insertion and removal with no discomfort and/or migration, would have no biofilm formation or encrustation, and would also maintain patient's quality of life. Materials and methods. In this mini review we outline the engineering developments relating to stent material, design and coating. Results. The...
Article
Manning’s empirical formula in conjunction with Strickler’s scaling is widely used to predict the bulk velocity $V$ from the hydraulic radius $R_{h}$ , the roughness size $r$ and the slope of the energy grade line $S$ in uniform channel and pipe flows at high bulk Reynolds numbers. Despite their importance in science and engineering, both Manning’s...
Conference Paper
Ureteral stents are often associated with high failure rates and complications that impact on both patients’ quality of life and costs for national healthcare services. The formation of encrusting deposits over the stent surface is recognised as one of the primary determinants of stent failure. In the present study we developed a microfluidic-based...
Article
It is commonly assumed that stream-dwelling fish should select positions where they can reduce energetic costs relative to benefits gained and enhance fitness. However, the selection of appropriate hydrodynamic metrics that predict space use is the subject of recent debate and a cause of controversy. This is for three reasons: 1) flow characteristi...
Article
The wakes and the drag forces of canopy patches with different densities, immersed in turbulent boundary layers, are investigated experimentally. The patches are circular (with outer diameter D) and are made of several identical circular cylinders (height, H and diameter, d). The bulk aspect ratio of all the patches (AR = H~D) was fixed at 1 and th...
Article
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The compensated three-dimensional turbulent kinetic energy spectrum exhibits a peculiar bump at wave numbers in the vicinity of the crossover from inertial to viscous regimes due to pile up in turbulent kinetic energy, a phenomenon referred to as the bottleneck effect. The origin of this bump is linked to an inflection point in the second-order str...
Article
The scaling of the scour depth of equilibrium at the base of a solid cylinder immersed within an erodible granular bed and impinged by a turbulent shear flow is investigated here, for the first time, by means of the phenomenological theory of turbulence. The proposed theory allows the derivation of a predictive formula that (i) includes all the rel...
Article
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Anthropogenic structures (e.g. weirs and dams) fragment river networks and restrict the movement of migratory fish. Poor understanding of behavioural response to hydrodynamic cues at structures currently limits the development of effective barrier mitigation measures. This study aimed to assess the effect of flow constriction and associated flow pa...
Article
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As rainfall intensities increase so does the risk of scour damage to river crossings. Scour inspections are traditionally carried out by divers, but the water around bridge piers is often turbulent and murky such that little can be seen. This paper reports on a trial inspection of the underwater foundations of the 1889 River Hamble railway viaduct...
Article
Connections between the wall-normal turbulent velocity spectrum E_{ww}(k) at wave number k and the mean velocity profile (MVP) are explored in pressure-driven flows confined within smooth walls at moderate to high bulk Reynolds numbers (Re). These connections are derived via a cospectral budget for the longitudinal (u^{'}) and wall-normal (w^{'}) v...
Article
A new formula to predict the scour depth of equilibrium around bridge piers (i.e. ys) under clear water conditions is derived using principles pertaining to the phenomenological theory of turbulence. The derivation provides insights into the relation between ys and the so-called relative coarseness (i.e. a/d, where a and d are bridge-pier and sedim...
Article
A large number of experiments and numerical simulations have proved that friction factors in laminar channel flows are roughness-dependent provided that the ratios between roughness and channel height (i.e., the relative roughness) exceed some threshold values. However, it is not yet clear what are the causes that lead to this anomalous behaviour....
Article
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Connections are explored between spectral descriptions of turbulence and the mean velocity profile in the equilibrium layer of wall-bounded flows using a modeled budget for the co-spectral density. Using a standard model for the wall normal velocity variance and a Rotta-like return-to-isotropy closure for the pressure-strain effects, the co-spectru...
Article
The stability of open-channel flows (or film flows) has been extensively investigated for the case of impermeable smooth walls. In contrast, despite its relevance in many geophysical and industrial flows, the case that considers a permeable rather than an impermeable wall is almost unexplored. In the present work, a linear stability analysis of a f...
Article
Full-text available
Describing the canonical properties of turbulent flows over rough-permeable walls such as gravel beds, vegetated- or snow-covered surfaces have, to date, resisted complete theoretical treatment. The major complication in describing such geophysical flows is that the friction factor - Reynolds number relationships significantly deviate from their co...
Article
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This study presents spatiotemporally-resolved measurements of surface shearstress τs in live plant canopies and rigid wooden cube arrays to identify the sheltering capability against sediment erosion of these different roughness elements. Live plants have highly irregular structures that can be extremely flexible and porous resulting in considerabl...
Article
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Laser Doppler anemometery and laser-induced fluorescence techniques were used to explore the spatial structure of the flow within and above finite cavities created within porous and solid media. The cavities within these two configurations were identical in size and were intended to mimic flow disturbances created by finite gaps and forest clearing...
Article
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This paper presents an experimental study devoted to investigating the effects of permeability on wall turbulence. Velocity measurements were performed by means of laser Doppler anemometry in open channel flows over walls characterized by a wide range of permeability. Previous studies proposed that the von Kármán coefficient associated with mean ve...
Article
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This study presents the results from a series of wind-tunnel experiments designed to investigate the aerodynamic roughness length z 0 of fresh snow under no-drift conditions. A two-component hot-film anemometer was employed to obtain vertical profiles of velocity statistics in a zero pressure gradient turbulent boundary layer for flow over naturall...
Article
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Mountain snow covers typically become patchy over the course of a melting season. The snow pattern during melt is mainly governed by the end of winter snow depth distribution and the local energy balance. The objective of this study is to investigate micrometeorological processes driving snow ablation in an Alpine catchment. For this purpose we com...
Article
Full-text available
Mountain snow covers typically become patchy over the course of a melting season. The snow pattern during melt is mainly governed by the end of winter snow depth distribution and the local energy balance. The objective of this study is to investigate micrometeorological processes driving snow ablation in an Alpine catchment. For this purpose we com...
Article
Full-text available
The experimental results of Nikuradse and the concept of hydraulically smooth, transitional, and rough flow regimes are commonly used as a benchmark for data interpretation and modeling of hydraulic resistance. However, Nikuradse's experiments were carried out in pipes with impermeable rough-walls whereas many geophysical flows occur over permeable...
Article
It has long been recognised in many branches of aeolian research that the process of sediment transport by the wind alters the surface aerodynamics. This effect is less clear over snow surfaces, particularly because of the difficulty of accurately identifying the contribution of surface topography and surface change. We present a synopsis of data f...
Article
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The formation, growth, and destruction of surface hoar crystals is an important feature of mountain snow covers as buried surface hoar layers are a frequent weak layer leading to unstable snowpacks. The energy and mass exchange associated with surface hoar dynamics is further an important part of land-atmosphere interaction over snow. A quantitativ...
Article
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The behavior of turbulent open channel flows over permeable surfaces is not well understood. In particular, it is not clear how the surface and the subsurface flow within the permeable bed interact and influence each other. In order to clarify this issue we carried out two sets of experiments, one involving velocity measurements in open channel flo...
Article
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The surface roughness is essential for all turbulent exchange processes within the lower part of the atmospheric boundary layer. Consequently, a proper representation of the surfaces roughness is needed in every mathematical description of near surface mass-, energy- and momentum exchange processes. Considering the vertical mean velocity profile of...
Article
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We present a laboratory experimental investigation of the interaction between the turbulent flow in an open channel and the turbulent flow within its very permeable bed. The bed was composed of uniform-size spheres packed in a cubic pattern. Fluid velocities were measured by Particle Image Velocimetry (PIV), which allowed us to investigate the spat...
Article
The formation of surface hoar, which takes predominantly place during cold and clear nights over snow covered surfaces, is particularly important for avalanche formation since a buried surface hoar layer forms very often a significant weak layer. We present measurements and simulations of surface hoar formation at an Alpine study plot in the Swiss...
Article
Velocity profiles over fresh fallen snow surfaces have been measured in the SLF cold atmospheric boundary layer wind tunnel. Aerodynamic roughness lengths z0 have been estimated from log-law velocity profile fitting. In parallel, photographs of the snow surfaces have been taken and evaluated using digital image analysis giving snow surface contour...
Article
Full-text available
We present results from a series of experiments in which fresh snow roughness was measured by means of digital photography and analyzed using the random field approach. The aim of the paper is to investigate the scaling properties of fresh-snow-covered surfaces and to capture key roughness length scales which can characterize the surface geometry a...
Article
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We present experimental results on the snow drift in a turbulent boundary layer over a flat fresh snow-covered surface. Vertical profiles of mass flux and of the distribution of particle diameters were obtained by means of a pair of Snow Particle Counters parallel with measurements of the stream-wise velocity profile. The aim of the paper is to dis...
Article
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This paper presents a review of recent experimental and numerical studies which deal with the analysis of form-induced stress in rough wall turbulent boundary layers. The aim of the paper is to assess the importance of this stress for various rough wall geometries and flow conditions. Analysis of the significance of form-induced stress is first per...
Article
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This paper explores the concept of a macroscopic boundary between turbulent flows above and within rough permeable walls. The macroscopic boundary and the associated conditions for macroscopic flow variables have been thoroughly investigated for laminar, but not for turbulent flows. The literature on laminar flows follows two main conceptual models...
Article
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The roughness characteristics of snow covered surfaces are one of the key parameters influencing surface energy and mass transfer. In particular, finding relationships between surface roughness geometry and the aerodynamic roughness length z0 is very desirable since z0 is an important parameter in any numerical model designed to simulate processes...
Article
Vapor exchange processes between the snow surface and the lower atmosphere lead to mass sublimation or deposition. While the former usually occurs during day, the latter often co-occurs at night with the formation of surface hoars. These crystals, when buried after snow falls, often form failure planes for avalanches. Understanding surface hoar for...
Article
The deposition and attachment mechanism of settling snow crystals during snowfall dictates the very initial structure of ice within a natural snowpack. In this letter we apply ballistic deposition as a simple model to study the structural evolution of the growing surface of a snowpack during its formation. The roughness of the snow surface is predi...
Article
Full-text available
The deposition and attachment mechanism of settling snow crystals during snowfall dictates the very initial structure of ice within a natural snowpack. In this letter we apply ballistic deposition as a simple model to study the structural evolution of the growing surface of a snowpack during its formation. The roughness of the snow surface is predi...
Article
Full-text available
We present the velocity profile measured within a porous bed below rough turbulent open channel flow. Mean streamwise velocity has a minimum in the top pore, just below the bed surface, and then increases towards a constant value in the deeper pores. We argue that the velocity minimum in the top pore is due to enhanced turbulence generated within t...
Article
We investigate the turbulent structure of shallow open channel flows where the flow depth is too small �compared with the roughness height� to form a logarithmic layer but large enough to develop an outer layer where the flow is not directly influenced by the roughness elements. Since the log layer is not present, the displacement height d, which d...