Michele Larcher

• Free University of Bozen-Bolzano

Climate data plays a crucial role in water resources management, which is becoming an increasingly relevant asset in all types of hydrological analysis not only for climate change studies but for various horizon forecasting. Though the ever-improving accuracy of climate models' spatial and temporal resolution has surged the validity of their output...

This research aims to experimentally characterize cooling, clogging and jamming of a dry granular flow in a chute partially obstructed by a stopping wall with two slits adjacent to the side walls. We ensemble‐average velocities, determined with Particle Tracking Velocimetry, and its fluctuations, to compute mean flow and granular temperature fields...

We study the behaviour of a particle bed immersed in water when a flow generated by an oscillating plate is induced above it. We first consider a rigid plate submerged and oscillated over a particle bed. During upward motion of the plate, a portion of the bed fails, allowing particle displacement, and the bed surface to deform into a heap. We have...

Using the global climate model outputs without any adjustment may bring errors in water resources and climate change investigations. This study tackles the critical issue of bias correction temperature in ERA5-Land reanalysis for 10 ground stations in the northern Italy using 9 machine learning (ML) techniques. Among standalone ML models, XGBoost r...

The dataset provided in this paper refers to an experimental campaign conducted in Laboratory of Fluid Dynamics (LTDF) of the Free University of Bozen-Bolzano at NOI Techpark aiming to understand the movement of granular material in fluids of low viscosity and density exhibited in debris flows. One experimental test was performed consisting of 31 r...

The water industry is facing significant challenges due to the effects of climate change and energy crises. To address these issues, the water sector is undergoing a digital transformation, leveraging digital technologies and methods, such as artificial intelligence and smart sensors, to improve sustainable supply, distribution, and treatment of wa...

Kinetic theory is used to propose and solve boundary value problems for fully developed, steady, dense gravity-driven flows of mixtures composed of identical inelastic spheres and water over both inclined erodible beds and rigid, bumpy bases confined by vertical sidewalls. We solve the boundary value problems assuming values of the mass density and...

Drinking water demand modelling and forecasting is a crucial task for sustainable management and planning of water supply systems. Despite many short-term investigations, the medium-term problem needs better exploration, particularly the analysis and assessment of meteorological data for forecasting drinking water demand. This work proposes to anal...

The ongoing pandemic has driven the attention of both policy makers and professionals of the building sector towards the need for proper ventilation of the indoor environment. Despite accurate ventilation control only being available with mechanical ventilation systems, in several countries worldwide the renovation of indoor air relies mainly on na...

We phrase boundary-value problems for a dense, steady, fully developed, gravitational flow of identical inelastic spheres and water over an inclined erodible bed in the presence of sidewalls. The mass density and the size of the spheres are that of the particles employed in laboratory experiments by Armanini et al., [J. Fluid Mech. 532, 269 (2005)]...

In this letter, we discuss how flow inhomogeneity affects the self-diffusion behavior in granular flows. Whereas self-diffusion scalings have been well characterized in the past for homogeneous shearing, the effect of shear localization and nonlocality of the flow has not been studied. We therefore present measurements of self-diffusion coefficient...

In this Letter, we discuss how flow inhomogeneity affects the self-diffusion behavior in granular flows. Whereas self-diffusion scalings have been well characterized in the past for homogeneous shearing, the effect of shear localization and nonlocality of the flow has not been studied. We, therefore, present measurements of self-diffusion coefficie...

We report on the discovery, using numerical simulations, of a segregation pattern in high-speed granular flows, in which size segregation is primarily driven by two-dimensional granular temperature gradients, rather than by gravity. In contrast to slower flows on gentle slopes, in high-speed flows on steep slopes, large particles no longer accumula...

Short-term streamflow forecasting is crucial for many activities including flood risk mitigation, multi-use water management and production planning for hydropower plants. Several studies have shown that data-driven approaches are more suitable for operational forecasting than physics-based models due to the higher flexibility and reproducibility o...

To enable the mechanistic description of the mixing of larger particles in gas-fluidized beds in models (e.g. fuel particles in combustors), knowledge about the rheology of the bed emulsion is required. Here, it is crucial to determine the drag on large fuel-alike particles. This work presents the experimental work on the fate of 13 different solid...

We report on measurements of self-diffusion coefficients in discrete numerical simulations of steady, homogeneous, collisional shearing flows of nearly identical, frictional, inelastic spheres. We focus on a range of relatively high solid volume fractions that are important in those terrestrial gravitational shearing flows that are dominated by col...

We report on measurements of self-diffusion coefficients in discrete numerical simulations of steady, homogeneous, collisional shearing flows of nearly identical, frictional, inelastic spheres. We focus on a range of relatively high solid volume fractions that are important in those terrestrial gravitational shearing flows that are dominated by col...

Particle fracture, the formation of small particles as the result of the breakage of large ones, and aggregation, the formation of large particles as the result of the combination of small ones, have important implications in industry (e.g. food processing, pharmaceutical production) and geophysics (e.g., snow avalanches and rock debris flows). Als...

We analyse the different morphologies induced by an oscillating plate above an erodible bed. We present some data describing how the shape and the stiffness of the plate affects the main features of the generated heap. We investigate several configurations with different geometries, frequencies and the amplitudes. Some preliminary results are avail...

We consider an inclined flow of two different types of spheres in which there is a dense collisional flow above a layered flow that involves force-chains that extend through its depth. In the latter, the granular temperature increases linearly from its base, in the former the granular temperature increases linearly from its top. Consequently, for s...

The aim of this work is to investigate the fluid dynamic behavior of a cold bubbling fluidized bed gasifier, both from an experimental and a numerical point of view. The experimental analysis has been carried out considering three heights of bed particles and several fluidization velocities for each height. The experimental average pressure drops t...

This work aims at comparing two different procedures used to downscale a real fluidized bed reactor for biomass gasification. According to the literature, two sets of non-dimensional parameters have been exploited: while the so-called full one takes into account all the necessary dimensionless coefficients, the so-called simplified one doesn't invo...

Profiles of concentration, velocity and granular temperature are measured in tilting flume and analyzed using kinetic theory of granular flow. Distributions of granular stresses across collisional transport layer are determined and linked to flow transport and friction conditions. Conditions under which the kinetic theory is applicable to intense b...

The paper deals with the interaction forces between the two phases of a granular flow immersed in water, analyzing in detail the effects on the drag of the concentration of the solid phase and of the interactions between velocities of the two phases and particle concentration. According to the system of equations, the relations between these variab...

A method for human safety assessment on a hydropeaked river reach is proposed and applied to an Alpine river. The human safety analysis during hydropeaking events is of particular interest because most of the Alpine watercourses are affected by hydropower plant energy production that cause rapid and frequent flow alterations (hydropeaking), but at...

The paper addresses the dynamic impact of channel flows of water and mixtures of water and sediments on a test wall. Two types of impact may occur: the first characterized by the formation of a complete reflected wave moving upstream; the second type consisting in the vertical deviation of the flow along the wall with a jet-like behaviour. The pape...

We investigate the mechanism of particle entrainment for dense, dry, collisional granular flows driven by gravity through a set of uniform-unsteady experiments. The flow evolves in time from a rest to a fully developed condition, but without any variability in the longitudinal direction. Using a high speed camera and particle tracking algorithms, w...

Flows involving solid particulates have been widely studied in recent years, but their dynamics are still a complex issue to model because they strongly depend on the interaction with the boundary conditions. We report on laboratory investigations regarding homogeneous and steady flows of identical particles over a loose bed in a rectangular channe...

A series of laboratory experiments on turbulent open-channel two-phase flow in a form of intense bed load transport is reported. Measurements in a laboratory tilting flume included camera based imaging techniques to identify the structure of the flow at the local level. Obtained experimental distributions of two-phase flow related parameters - gran...

We consider dense, inclined flows of spheres in which the particles translate in layers, whose existence may be promoted by the presence of a rigid base and/or sidewalls. We imagine that in such flows a sphere of a layer is forced up the back of a sphere of the layer below, lifting a column of spheres above it, and then falls down the front of the...

We phrase and solve boundary-value problems for the segregation of spheres with either equal density and different sizes, or the same size and different densities in flows of a clear fluid driven by gravity over an inclined, erodible bed in a wide channel. We assume that the flow is steady and uniform, collisions between particles dissipate little...

We outline the equations that govern the evolution of segregation of a binary mixture of spheres in flows down inclines. These equations result from the mass and momentum balances of a kinetic theory for dense flows of inelastic spheres that interact through collisions. The theory employed for segregation is appropriate for particles with relativel...

We consider the evolution of particle segregation in collisional flows of two types of spheres down rigid bumpy inclines in the absence of sidewalls. We restrict our analysis to dense flows and use an extension of kinetic theory to predict the concentration of the mixture and the profiles of mixture velocity and granular temperature. A kinetic theo...

We consider a steady, uniform, dense, fully-saturated, gravity-driven, inclined flow of water and identical spherical grains over an erodible bed between parallel, vertical sidewalls. The grains are inelastic and the energy lost in their interaction is also influenced by the fluid viscosity. We use an extension of kinetic theory for dense flows and...

In this work we present a model for granular flows saturated with water and driven by gravity, which is therefore well suited to the modeling of debris flows. These phenomena are treated with a two-phase approach. In particular in the case of interest for this work the liquid phase is water, while the solid phase is treated as a granular flow. The...

The paper presents a rheological model for gravity driven granular flows saturated with water. The model adopts the kinetic theory for the collisional regime, which is dominant near the free surface, while for the frictional regime a specific model is proposed, which matches the Coulombian condition at the boundary with the loose static bed. The so...

We study dry flows of two types of spheres down an inclined, rigid, bumpy bed in the absence of sidewalls. The flow is assumed to be steady and uniform in all but the direction normal to the free surface, collisions between particles are dissipative, and the sizes and masses of the particles are not too different. We restrict our analysis to dense...

We phrase and solve a problem of particle segregation in a dry flow of a binary mixture of spheres down an inclined bed in a wide channel. The flow is assumed to be steady and fully-developed, collisions between particles are dissipative, and the sizes and masses of the particles are not too different. We restrict our analysis to dense flows and us...

This work presents a model for gravity driven granular flows saturated with water, particularly suited for modeling of debris flows. To describe these natural phenomena a two-phase approach is necessary: the liquid-phase (the interstitial fluid), which usually is water treated with a Newtonian rheology, and the solid phase (the granular fluid). Her...

Debris flows are complex natural phenomena, characterized by a mixture of poorly sorted sediments and water driven by gravity. Depending on the size distribution, on the volume concentration of sediments and on the geometry and topography of the channel, flow conditions may be very different, ranging from very fast flows, dominated by granular coll...

Recent experimental results obtained at the University of Trento show that a liquid-granular wave can impact against a vertical obstacle producing two different mechanisms of reflection, depending on the Froude number: if the front is sufficiently fast, the flow is completely deviated in the vertical direction, producing a vertical jet-like bulge,...

We report on recent advances in experiments and modeling of particle-fluid flows that are relevant to an understanding of debris flows. We first describe laboratory experiments on steady, inclined flows of mixtures of water and a single idealized granular phase that focus on the differences in the depths and the velocity of the two phases and that...

A simple, robust, and accurate imaging technique is proposed to measure granular concentration profiles in channel flows of liquid-granular mixtures. We focus on moderate to high granular concentrations (5–50%), for which optical access is restricted to regions close to a transparent wall. To measure concentrations in this range, we illuminate soli...

We phrase and solve a problem of particle segregation in a dry flow of two sizes of spheres down an inclined bed in a wide channel. The flow is assumed to be steady and fully‐developed, collisions between particles are dissipative, and the sizes and masses of the particles are not too different. We restrict our analysis to dense flows and use an ex...

We present a detailed analysis of a free surface-saturated liquid-granular mixture flowing over a static loose bed of grains, where the coexistence of layers dominated by collisional and frictional interactions among particles was observed. Kinetic theory was applied to the flow described above and it proved suitable for describing a realistic beha...

We phrase and solve a problem of particle segregation in a flow of two sizes of spheres in water that is driven above by a clear fluid down an inclined erodible bed in a wide channel. The flow is assumed to be steady and fully-developed, collisions between particles are assumed to dissipate little energy, and the sizes and masses of the particles a...

The paper tackles some important issues regarding the dynamics of mixtures of grains and water, on the basis of a series of experiments on uniform channel flows of non-cohesive particles and water. Precise measurements of the granular concentration, temperature, velocity, normal and shear stresses are presented. The experiments show the existence o...

The paper documents a detailed set of measurements from laboratory experiments involving open–channel flows of granular–liquid mixtures. Polyvinyl Chloride pellets mixed with clear water are used, and represent simplified analogues of the mixtures of rocks and muddy water encountered in stony inertial debris flows. The flows are examined in steady...

The behavior of liquid-granular flows, driven by gravity, is experimentally analyzed. Two types of free-surface uniform flow can take place, having different boundary conditions at the bottom. The first one runs over a fixed surface behaving as a solid (non-deformable) impermeable wall; the second one runs over a mobile-bed at rest, formed by the s...

The principal features of debris flow are described. One section is devoted to debris-flow triggering, accounting for the geomechanical criteria by Takahashi (1978) and for most recent hydrological distributed models. In a second section, the rheology of debris flows is described: the theory of dispersive stresses by Bagnold, the kinetic theories o...

Laboratory experiments are conducted to study the rheological behaviour of high-concentration granular–liquid mixtures. Steady uniform free-surface flows are obtained using a recirculating flume. Cases in which a loose deposit forms underneath the flow are contrasted with runs for which basal shear occurs along the flume bottom. The granular motion...

The present paper aims to present the issues and the scope of the IMPACT research project in the field of dam-break induced geomorphic flows, to give an overview of the experi-mental work carried out in the frame of the research program, to summarize the new develop-ments in modeling, to outline the validation process and to give some practical con...

A set of stereoscopic imaging techniques is proposed for the measurement of rapidly flowing dispersions of opaque particles observed near a transparent wall. The methods exploit projective geometry and the Voronoï diagram. They rely on purely geometrical principles to reconstruct 3D particle positions, concentrations, and velocities. The methods ar...

New apparatuses were developed in the University of Trento to obtain mudflows in steady uniform conditions, in order to permit precise measurements of flow parameters. In a first experimental phase the natural material of the recent mudflow in South of Italy (Sarno, Campania) was employed, in a second phase a well-sorted porphyry material was utili...

This paper presents a theoretical approach to the problem of designing the opening in a slit-check dam. The approach is based on the conservation of the mass of water and sediments and on the energy balance under steady conditions. It leads to a relationship among opening width, sediment characteristics, mountain river geometry, and water and sedim...

Open-check darns are built in mountain streams to control sediment transport during a flood. Sediment passes through them at the lowest discharges, whereas deposition occurs during the highest discharges. Open-check dams are currently designed based mainly on construction experience. Modeling of hydraulics and bed morphology in check darns involves...

The first part of the note presents a theoretical and experimental approach to the problem of designing the opening in a slit check dam for debris flow events. It leads to a relationship among opening width, sediment characteristics, channel geometry and water and sediment discharge. The results have been verified in a laboratory investigation usin...

The paper presents a rational criterion to design the slit check dams to control mudflows and debris flows. The method here presented is based on the scheme proposed by Armanini & Larcher (2001) for the case of ordinary sediment transport and it is based on the balances of the solid and liquid phases of debris flow and mudflow and on momentum conse...

In this note we describe the procedures and the design assumptions under the project of restoration and the hydraulic defence constructions of the Quebrada San José de Galipán and Quebrada el Cojo which has been assigned to the Provincia Autonoma di Trento (Italy) and to the University of Trento. Of those assumptions, some crucial aspects are empha...

SOMMARIO. Questo file contiene le istruzioni per la formattazione delle memorie per il Convegno Nazio-nale di Idraulica e Costruzioni Idrauliche che siter a a Trento nel settembre 2004. Gli autori dovranno in-viare in formato PDF le memorie, scritte utilizzando il presente stile, al comitato organizzatore all'indirizzo: idratrento@ing.unitn.it o id...