Davide Poggi

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

Engineering

About

79
Publications
18,556
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3,131
Citations
Additional affiliations
March 2011 - present
Politecnico di Torino
Position
  • Professor (Associate)

Publications

Publications (79)
Article
Full-text available
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...
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
Full-text available
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
Full-text available
We review developments in the field of boundary-layer flow over complex topography, focussing on the period from 1970 to the present day. The review follows two parallel strands: the impact of hills on flow in the atmospheric boundary layer and gravity-driven flows on hill slopes initiated by heating or cooling of the surface. For each strand we co...
Article
Full-text available
Plain Language Summary Diagnosing the complex flow mechanisms that control mass transport and dispersion within forest canopies or vegetated streams is required in a plethora of applications spanning atmospheric and climate sciences, earth system modeling, ecology, and hydrology. Examples include pollen dispersal, residence time of volatile organic...
Article
Full-text available
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
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A rotary hydrostatic pressure machine (RHPM) is a hydropower converter for very low head applications (less than 2.5 m). An RHPM can be installed in straight canals, because its wheel can generate a hydraulic head as a result of the created dam effect. Some new experimental results on an RHPM are presented in this paper. Because of the asymmetric s...
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
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The effect of hydraulic resistance on the downstream evolution of the water surface profile h in a sloping channel covered by a uniform dense rod canopy following the instantaneous collapse of a dam was examined using flume experiments. Near the head of the advancing wavefront, where h meets the rods, the conventional picture of a turbulent boundar...
Conference Paper
Dambreak waves in a horizontal rectangular and smooth channel are measured using a number of low cost laser sources, fluorescent dies and Planar Laser Induced Fluorescence (PLIF). Even in such a simple configuration, the experiment are useful to investigate a number of factors such as: the initial wave formation process, the positive front propagat...
Conference Paper
The propagation of dam-break waves along a hillslope is studied by mean of a physical model and an image-analysis technique. The facility and the calibration phase are described. Preliminary results are given.
Article
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The aim of this work is to study the propagation of dam-break waves along a hillslope by mean of a physical model (basically i.e. a 3 x 4 m2 plane set downstream of a reservoir) build up in the Hydraulic Laboratory of the Politecnico di Torino. We want to recreate the water surface, to assess the shape of the flooded area and the arrival time of th...
Article
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The dispersion of heavy particles such as seeds within canopies is evaluated using Lagrangian stochastic trajectory models, laboratory, and field experiments. Inclusion of turbulent kinetic energy dissipation rate intermittency is shown to increase long-distance dispersal (LDD) by contributing to the intermittent ejection of particles to regions of...
Article
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Wave power is one of the most rich and promising sources of renewable energy for the future. Approximately 2000 TWh/year can be produced through the exploitation of the waveenergy potential. In the past four decades, hundreds of WaveEnergy Converters have been proposed and studied, but so far a conclusive architecture to harvest wave power has not...
Article
Full-text available
Connections between the spatial and temporal statistics of turbulent flow, and their possible convergence to ensemble statistics as assumed by the ergodic hypothesis, are explored for passive scalars within a rod canopy. While complete ergodicity is not expected to apply over all the spatial domain within such heterogeneous flows, the fact that can...
Article
Full-text available
Streamflow prediction in high-altitude scarcely-gauged catchments is essential for efficient water resources management and hydropower generation. Aim of this study is to estimate water resources availability (WRA) by the application of a standard rainfall-runoff model and to study its impact on mini-hydropower production with application to Mangla...
Conference Paper
The ergodic hypothesis is central to the statistical theory of turbulence and is implicitly assumed when interpreting many laboratory and field experiments. The hypothesis states that the time/space averaging of flow statistics converge to that of an ensemble of flows with independent realizations but similar initial and boundary conditions. Despit...
Article
Full-text available
A streamfunction-vorticity formulation is used to explore the extent to which turbulent and turbulently inviscid solutions to the mean momentum balance explain the mean flow across forest edges and within cavities situated inside dense forested canopies. The turbulent solution is based on the mean momentum balance where first-order closure principl...
Chapter
The exchange of scalars between the biosphere and the atmosphere has direct bearing on a large number of problems such as climate change, air and water quality, agricultural management and food security, landscape ecology, and decision making for environmental compliances and policy formulation. Near the canopy-atmosphere interface, turbulent fluct...
Conference Paper
Full-text available
In the past four decades, hundreds of Wave Energy Converters (WECs) have been proposed and studied, but so far a final architecture to harvest wave power has not been identified. Many engineering problems are still to be solved, like survivability, durability and effective power capture in a variable wave climate. ISWEC (Inertial Sea Wave Energy Co...
Chapter
Full-text available
The exchange of scalars between the biosphere and the atmosphere has direct bearing on a large number of problems such as climate change, air and water quality, agricultural management and food security, landscape ecology, and decision making for environmental compliances and policy formulation. Near the canopy-atmosphere interface, turbulent fluct...
Article
Full-text available
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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Almost all winter resorts rely on artificial snow production as a surrogate for natural snow when the natural snow cover is missing or inadequate. The sustainability of snowmaking practices represents a debated issue, with two contrasting views: on the one hand the need for enhancing the value of mountain regions in terms of touristic appeal; on th...
Article
Seed dispersal kernels of wind-dispersed species imprint the initial spatial template over which later demographic processes such as establishment or re-colonization operate from. A major knowledge gap in seed dispersal modeling by wind is the role of complex topography in modifying the kernel shape when referenced to the flat-world case. How compl...
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
Full-text available
The specification of a flow resistance factor to account for vegetative effects in the Saint-Venant equation (SVE) remains uncertain and is a subject of active research in flood routing mechanics. Here, an analytical model for the flow resistance factor is proposed for submerged vegetation, where the water depth is commensurate with the canopy heig...
Article
Micrometeorological measurements of aerosol sized dry particle deposition velocity (Vd) onto forested canopies have significantly advanced over the past two decades and now include both—airborne and stationary platforms. However, the interpretation of these Vd measurements still relies on stationary and planar homogeneous flow assumptions only appr...
Article
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The scalar concentration fluctuations within a plane parallel-to-the-ground surface were measured inside a model canopy composed of densely arrayed rods using the laser-induced fluorescence technique. Two-dimensional scalar concentration spectra were computed and were shown to exhibit an approximate −3 power-law scaling at wavenumbers larger than t...
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
Full-text available
Inferring the vertical variation of the mean turbulent kinetic energy dissipation rate (ε) inside dense canopies remains a basic research problem to be confronted. Using detailed laser Doppler anemometry (LDA) measurements collected within a densely arrayed rod canopy, traditional and newly proposed methods to infer ε profiles are compared. The tra...
Article
Full-text available
Virtually all reviews dealing with aerosol-sized particle deposition onto forested ecosystems stress the significance of topographic variations, yet only a handful of studies considered the effects of these variations on the deposition velocity (V d ). Here, the interplay between the foliage collection mechanisms within a dense canopy for differen...
Article
The modulation of turbulent energetics and their canonical length scales inside tall and dense canopies on complex terrain remains largely an unexplored topic though interest in these properties is now proliferating. These interests are motivated by footprint analysis when interpreting eddy-covariance derived evapo-transpiration (ET) measurements f...
Article
The exchange of water and nutrients between rivers and hyporheic zones has been recognized as a very important process for the stream ecosystem. This water exchange is generally explained by pressure gradients on the riverbed that are induced by fluvial geomorphological features or by turbulent coherent structures. In this work we discuss a differe...
Article
Full-text available
The past decade witnessed rapid developments in remote sensing methods that now permit an unprecedented description of the spatial variations in water levels (Hw), canopy height (hc), and leaf area density distribution (a) at large spatial scales. These developments are now renewing interest in effective resistance formulations for water flow withi...
Article
Full-text available
How the presence of a canopy alters the clustering and the fine scale intermittency exponents and any possible connections between them remains a vexing research problem in canopy turbulence. To begin progress on this problem, detailed flume experiments in which the longitudinal and vertical velocity time series were acquired using laser Doppler an...
Article
Full-text available
The effects of surface roughness on various measures of fine-scale intermittency within the inertial subrange were analyzed using two data sets that span the roughness "extremes" encountered in atmospheric flows, an ice sheet and a tall rough forest, and supplemented by a large number of existing literature data. Three inter-related problems pertai...
Article
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To investigate how velocity variances and spectra are modified by the simultaneous action of topography and canopy, two flume experiments were carried out on a train of gentle cosine hills differing in surface cover. The first experiment was conducted above a bare surface while the second experiment was conducted within and above a densely arrayed...
Article
Full-text available
Resolving every detail of the three-dimensional canopy morphology and its underlying topography remains untenable when modeling high Reynolds number geophysical flows. How to represent the effects of such a complex morphological variability and any concomittant topographic variability into one-dimensional bulk flow representation remains a fundamen...
Article
Full-text available
Simplifications and scaling arguments employed in analytical models that link topographic variations to mean velocity perturbations within dense canopies are explored using laboratory experiments. Laser Doppler anemometry (LDA) measurements are conducted in a neutrally-stratified boundary-layer flow within a large recirculating flume over a train o...
Article
Full-text available
Abstract How to represent the effects of variable canopy morphology on turbulence remains a fundamental challenge yet to be confronted.
Article
The choice of the Kolmogorov constant (C0) in Lagrangian Stochastic Models (LSMs) for canopy flows remains a subject of debate and uncertainty. This uncertainty stems from the fact that canopy flows are highly dissipative, lack a well-defined inertial subrange (ISR) in their energy cascade, and in the deeper layers of the canopy, the attenuation of...
Article
Full-text available
Recent theories and model calculations for flows inside canopies on gentle hilly terrain suggest that the impact of advection and pressure perturbations on the mean momentum budget remains problematic when the canopy adjustment length (Lc) is comparable to the hill half-length (L) (referred to as narrow gentle hills). To progress on this problem, d...
Article
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A number of analytical and numerical studies employing first-order closure principles have suggested that canopy flows on gentle sinusoidal hills feature a recirculation region, situated on the lee side, that can dramatically affect scalar transfer between the biosphere and the atmosphere. To date, the onset of this region, and its effects on bulk...
Article
Full-text available
Progress on practical problems such as quantifying gene flow and seed dispersal by wind or turbulent fluxes over nonflat terrain now demands fundamental understanding of how topography modulates the basic properties of turbulence. In particular, the modulation by hilly terrain of the ejection-sweep cycle, which is the main coherent motion responsib...
Article
Full-text available
Gentle topographic variations significantly alter the mass and momentum exchange rates between the land surface and the atmosphere from their flat-world state. This recognition is now motivating basic studies on how a wavy surface impacts the flow dynamics near the ground for high bulk Reynolds numbers Re h . Using detailed flume experiments on a t...
Article
Full-text available
The Markov order of a time series is an important measure of the "memory" of a process, and its knowledge is fundamental for the correct simulation of the characteristics of the process. For this reason, several techniques have been proposed in the past for its estimation. However, most of this methods are rather complex, and often can be applied o...
Article
Full-text available
The turbulent flow inside dense canopies is characterized by wake production and short-circuiting of the energy cascade. How these processes affect passive scalar concentration variability in general and their spectral properties in particular remains a vexing problem. Progress on this problem is frustrated by the shortage of high resolution spatia...
Article
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Using an incomplete third-order cumulant expansion method (ICEM) and standard second-order closure principles, we show that the imbalance in the stress contribution of sweeps and ejections to momentum transfer (ΔS o ) can be predicted from measured profiles of the Reynolds stress and the longitudinal velocity standard deviation for different bound...
Article
Full-text available
Modeling scalar transport within canopies remains a vexing research problem in eco-hydrology and eco-hydraulics. Canopy turbulence is inhomogeneous, non-Gaussian, and highly dissipative, thereby posing unique challenges to three-dimensional Lagrangian Dispersion Models (LDM). Standard LDM approaches usually satisfy the well-mixed condition and acco...
Chapter
One of the defining syndromes of turbulence is nonlinear stochasticity. This view of turbulence motivated the development of statistical mechanics theories that have served to connect the basic Navier-Stokes (NS) equations of motion to the statistical results of numerous field experiments. In general, the proper averaging operator for stochastic pr...
Article
Full-text available
Topography influences many aspects of forest-atmosphere carbon exchange; yet only a small number of studies have considered the role of topography on the structure of turbulence within and above vegetation and its effect on canopy photosynthesis and the measurement of net ecosystem exchange of CO2 (Nee) using flux towers. Here, we focus on the inte...
Article
Full-text available
In contrast to atmospheric surface-layer (ASL) turbulence, a linear relationship between turbulent heat fluxes (FT) and vertical gradients of mean air temperature within canopies is frustrated by numerous factors, including local variation in heat sources and sinks and large-scale eddy motion whose signature is often linked with the ejection-sweep...
Chapter
Full-text available
Long-distance dispersal (LDD) of pollen in conifers presents a risk for transgenic escape into unmanaged forests. Here, we report simulations of transgenic pollen dispersal and LDD from genetically modified forests using a mechanistic turbulent dispersal model. The dispersal model is based on coupled Eulerian-Lagrangrian closure (CELC) principles t...
Article
Virtually all recent reviews concerning surface-atmosphere water vapor and momentum exchange have expressed the need to confront the problem of turbulent flows within plant canopies on non-flat terrain. In particular, the presence of topographic variability induces advective fluxes that disbalance the one-to-one relationship between plant evapotran...
Article
Full-text available
Estimating transpiration and water flow in trees remains a major challenge for quantifying water exchange between the biosphere and the atmosphere. We develop a finite element tree crown hydrodynamics (FETCH) model that uses porous media equations for water flow in an explicit three-dimensional branching fractal tree-crown system. It also incorpora...
Article
Full-text available
We introduce an analytical model, the Wald analytical long-distance dispersal (WALD) model, for estimating dispersal kernels of wind-dispersed seeds and their escape probability from the canopy. The model is based on simplifications to well-established three-dimensional Lagrangian stochastic approaches for turbulent scalar transport resulting in a...
Article
Full-text available
We introduce an analytical model, the Wald analytical long‐distance dispersal (WALD) model, for estimating dispersal kernels of wind‐dispersed seeds and their escape probability from the canopy. The model is based on simplifications to well‐established three‐dimensional Lagrangian stochastic approaches for turbulent scalar transport resulting in a...
Article
Full-text available
It is recognized that topography influences almost all aspects of forest-atmosphere carbon exchange, yet a limited number of studies considered the role of topography on the structure of turbulence within vegetation and its ultimate effect on photosynthesis and net ecosystem carbon fluxes. Here, we focus on the interplay between radiative transfer,...