Leonardo. Tecnica e territorio.

Il catalogo della mostra presso il castello del Valentino (15 aprile-14 luglio 2019), svolta in perfetto parallelismo con quella presso i Musei Reali di Torino, esplora, nel cinquecentenario della morte del Vinciano, il lascito di Leonardo nel contesto della cultura politecnica. Organizzata in tre stanze dell'appartamento dorato o meridionale del Palazzo (Gigli, Vallantino e Zodiaco o Pianeti), corrisponde ad altrettante sezioni, di cui il catalogo rende ragione. I temi delle edizioni critiche dei codici di Leonardo, delle costruzioni di macchine, dello studio dei minerali e delle pietre da costruzione, della formazione della sensibilità geografica si intrecciano con l'esposizione di esemplari, anche di pregio, appartenenti alle collezioni politecniche, in un dialogo serrato tra lascito del Vinciano e acquisizione di consapevolezza da parte di architetti e ingegneri. Il catalogo è anche l'occasione per approfondire, in ampie schede, la natura dei singoli manufatti presentati, e si presenta in versione bilingu

Impact of structural heterogeneity on solute transport andmixing in unsaturated porous media: An experimental study

International audienceSolute transport in unsaturated porous media plays a crucial role in environmental processesaffecting soils, the unsaturated zone, and aquifers lying below. These processes include nutrientand pesticide leaching in soils, contaminant migration to aquifers and degradation in the vadosezone, and nutrient exchange at the soil-river interface, to name a few. Natural porous media arecharacterized by structural heterogeneity in the pore sizes disorder and their spatialarrangements. The impact of pore size heterogeneity on the spreading and mixing of a soluteplume, and the resulting reaction rates, are not well understood for unsaturated flow. In addition,these processes can be affected by incomplete mixing at the pore scale. Thus, direct pore-scaleexperimental measurements are needed to gain a comprehensive understanding of the mixingstate of the system. Our goals are to 1) study the impact of structural heterogeneity on fluid phasedistributions and 2) establish how the arrangement of fluid phases impacts solute spreading andmixing. We use micromodel experiments with two-dimensional porous media. The samples arecreated by placing an array of circular posts in a Hele-Shaw-type flow cell. We vary theheterogeneity by controlling the circular posts’ diameters disorder and correlation length of theirspatial distribution. In the first stage of each experiment, we simultaneously inject liquid and air toestablish an unsaturated flow pattern with a connected liquid phase cluster. Then, we introduce aconservative fluorescent solute pulse with the moving liquid phase. We track the soluteconcentration and gradients’ evolution by taking periodic images of the flow cell and analyzingtheir fluorescence intensity. In addition to unsaturated flow experiments, our system allows us tostudy the impact of pore size disorder and correlation on solute mixing in saturated porous mediaand even directly quantifying fast reaction products’ concentrations. Initial results confirmprevious findings on the impact of desaturation on enhanced mixing rates for a single porousmedium geometry. In addition, our use of a continuous solute pulse highlights regions thatmaintain a high mixing rate at the interface between mobile and stagnant liquid phase parts.Ongoing experiments explore the impact of increasing pore size disorder and correlation lengthon fluid phase distributions and mixing rates

Impact of structural heterogeneity on solute transport andmixing in unsaturated porous media: An experimental study

International audienceSolute transport in unsaturated porous media plays a crucial role in environmental processesaffecting soils, the unsaturated zone, and aquifers lying below. These processes include nutrientand pesticide leaching in soils, contaminant migration to aquifers and degradation in the vadosezone, and nutrient exchange at the soil-river interface, to name a few. Natural porous media arecharacterized by structural heterogeneity in the pore sizes disorder and their spatialarrangements. The impact of pore size heterogeneity on the spreading and mixing of a soluteplume, and the resulting reaction rates, are not well understood for unsaturated flow. In addition,these processes can be affected by incomplete mixing at the pore scale. Thus, direct pore-scaleexperimental measurements are needed to gain a comprehensive understanding of the mixingstate of the system. Our goals are to 1) study the impact of structural heterogeneity on fluid phasedistributions and 2) establish how the arrangement of fluid phases impacts solute spreading andmixing. We use micromodel experiments with two-dimensional porous media. The samples arecreated by placing an array of circular posts in a Hele-Shaw-type flow cell. We vary theheterogeneity by controlling the circular posts’ diameters disorder and correlation length of theirspatial distribution. In the first stage of each experiment, we simultaneously inject liquid and air toestablish an unsaturated flow pattern with a connected liquid phase cluster. Then, we introduce aconservative fluorescent solute pulse with the moving liquid phase. We track the soluteconcentration and gradients’ evolution by taking periodic images of the flow cell and analyzingtheir fluorescence intensity. In addition to unsaturated flow experiments, our system allows us tostudy the impact of pore size disorder and correlation on solute mixing in saturated porous mediaand even directly quantifying fast reaction products’ concentrations. Initial results confirmprevious findings on the impact of desaturation on enhanced mixing rates for a single porousmedium geometry. In addition, our use of a continuous solute pulse highlights regions thatmaintain a high mixing rate at the interface between mobile and stagnant liquid phase parts.Ongoing experiments explore the impact of increasing pore size disorder and correlation lengthon fluid phase distributions and mixing rates

Two-phase flow in geological rough fractures to decipher CO2 residual trapping in fractured aquifers: an analog experimental study

International audienceResearch on multiphase flow in porous media has been very extensive in the last 40 years, at both the pore and the continuum scales. However, a comprehensive understanding of the phenomenology of two-phase flow in geological fractures, encompassing flow regimes (capillary number Ca), fluid properties (viscosity ratio M), and the geometry (aperture fields), remains elusive. We investigate residual trapping of CO2 in fractured reservoirs at the fracture scale, exploring the complex interplay between fracture surface roughness and the displacement of fluid-fluid interfaces. Our approach explores the phenomenology of two-phase flow in fractures, systematically taking into meticulous consideration the fluid properties, flow conditions, and fracture geometry. To this aim, we have developed a transparent fracture flow cell with self-affine rough-walled surfaces and precisely-controlled mean aperture, which can be varied. The fracture wall geometry is generated from numerical models that are consistent with the well-known stochastic geometric properties of geological fractures. A camera allows recording the dynamics of the fluid phases’ spatial distribution within the fracture plane. The displacement patterns are characterized as functions of Ca, M, the density difference of the fluids, and the fracture’s geometrical parameters. We thus aim to characterize the amount of supercritical CO2 trapped in fractured aquifers as a function of those controlling parameters

Two-phase flow in geological rough fractures to decipher CO2 residual trapping in fractured aquifers: an analog experimental study

International audienceResearch on multiphase flow in porous media has been very extensive in the last 40 years, at both the pore and the continuum scales. However, a comprehensive understanding of the phenomenology of two-phase flow in geological fractures, encompassing flow regimes (capillary number Ca), fluid properties (viscosity ratio M), and the geometry (aperture fields), remains elusive. We investigate residual trapping of CO2 in fractured reservoirs at the fracture scale, exploring the complex interplay between fracture surface roughness and the displacement of fluid-fluid interfaces. Our approach explores the phenomenology of two-phase flow in fractures, systematically taking into meticulous consideration the fluid properties, flow conditions, and fracture geometry. To this aim, we have developed a transparent fracture flow cell with self-affine rough-walled surfaces and precisely-controlled mean aperture, which can be varied. The fracture wall geometry is generated from numerical models that are consistent with the well-known stochastic geometric properties of geological fractures. A camera allows recording the dynamics of the fluid phases’ spatial distribution within the fracture plane. The displacement patterns are characterized as functions of Ca, M, the density difference of the fluids, and the fracture’s geometrical parameters. We thus aim to characterize the amount of supercritical CO2 trapped in fractured aquifers as a function of those controlling parameters

Development of a Beam Loss Monitor and Transverse Beam Dynamics Studies at ARRONAX C70XP Cyclotron

International audienceThe ARRONAX Interest Public Group uses a multi-particle, high energy and high intensity industrial accelerator which has several beamlines used for various purposes. For improvement of operations, ARRONAX has foster and installed robust air-based Beam Loss Monitors (BLMs) outside the beam pipes. BLMs consist of four active detecting plates and are integrated within the experimental physics and industrial control system (EPICS) monitoring and data acquisition system. Each BLM has been tested for the pre-commissioning phase with beams at low intensity (600pA to 6nA on target). Comparative studies and selection of the BLMs has led to their installation at high intensity beam lines. BLMs are now used in beam dynamics studies to investigate transverse characteristics while in regular operation. They support present and future operations extension foreseen at ARRONAX. The results from experimental studies on BLMs at low beam intensity and status of beam dynamics studies at high intensity (A) are presented here. Keywords: BLM, beam dynamics, EPICS, Gas ionization detector, cyclotron, proton

Optical thermometry to assess the impact of structural heterogeneities on coupled flow and heat transport in permeable media

National audienceA novel application of phosphor themometry is proposed aiming to evaluate local thermal nonequilibrium effects on heat transport in heterogenous porous and fractured media. This experimental approach overcomes technical challenges as current experimental techniques, based on point (sensor) temperature measurements, do not allow capturing the interplay between temperature gradients and 3D flow topologies. A major technological challenge addressed in this project is the design and development of new experimental methodologies to perform dynamical pore scale optical measurements of temperature.It offers the possibility of presenting high resolution optical monitoring of the time-evolving temperature field. Fluid thermometry uses solid phosphor particles seeded into the flow as a tracer and probes their temperature-dependent luminescence properties using light sources and cameras. The fluid temperature is then obtained from the luminescence emission of the particles through a calibration, with a precision better than 0.3°C

Optical thermometry to assess the impact of structural heterogeneities on coupled flow and heat transport in permeable media

National audienceA novel application of phosphor themometry is proposed aiming to evaluate local thermal nonequilibrium effects on heat transport in heterogenous porous and fractured media. This experimental approach overcomes technical challenges as current experimental techniques, based on point (sensor) temperature measurements, do not allow capturing the interplay between temperature gradients and 3D flow topologies. A major technological challenge addressed in this project is the design and development of new experimental methodologies to perform dynamical pore scale optical measurements of temperature.It offers the possibility of presenting high resolution optical monitoring of the time-evolving temperature field. Fluid thermometry uses solid phosphor particles seeded into the flow as a tracer and probes their temperature-dependent luminescence properties using light sources and cameras. The fluid temperature is then obtained from the luminescence emission of the particles through a calibration, with a precision better than 0.3°C