Granular flow in equilibrium with the bottom: experimental analysis and theoretical prediction

International audienceThe paper presents measurements performed on the granular flow that develops in a drum partially filled with sand grains and rotating at various speeds. The aims of the paper are: to provide experimental evidence and measurements on grain flow in a drum; to compare theoretical and experimental velocity profiles; to point out discrepancies among theory and experiments. Velocity and "temperature" profiles were obtained with a Laser Doppler Anemometer (LDA) in the mid-section of the stream, where the flow is usually uniform; image analysis and visual observations of the flow were also carried out to evaluate the local slope, the depths of the characteristic flow regions and the concentration of the granular material. A semi-empirical relation that fits the experimental velocity profiles is presented and compared with Takahashi's velocity distributions for rigid and erodible bed. As proven by the distributions of free surface elevation, velocity, volumetric concentration and grain size across the drum, the three-dimensional nature of the flow field is not negligible. By increasing the drum rotation speed, in correspondence with critical and supercritical flows, changes in the flow regime are observed with formation of quasi-stationary surface waves. Wave development is described by analysing the extension and form of the experimental and theoretical velocity profiles. Wave effects on measurements are quantified and checked comparing the free-surface velocity-discharge relation obtained from experiments and from Takahashi's model for erodible bed

Wave simulation for the design of an innovative quay wall: the case of Vlorë Harbour

Sea states and environmental conditions are basic data for the design of marine structures. Hindcasted wave data have been applied here with the aim of identifying the proper design conditions for an innovative quay wall concept. In this paper, the results of a computational fluid dynamics model are used to optimise the new absorbing quay wall of Vlorë Harbour (Republic of Albania) and define the design loads under extreme wave conditions. The design wave states at the harbour entrance have been estimated analysing 31 years of hindcasted wave data simulated through the application of WaveWatch III. Due to the particular geography and topography of the Bay of Vlorë, wave conditions generated from the north-west are transferred to the harbour entrance with the application of a 2-D spectral wave module, whereas southern wave states, which are also the most critical for the port structures, are defined by means of a wave generation model, according to the available wind measurements. Finally, the identified extreme events have been used, through the NewWave approach, as boundary conditions for the numerical analysis of the interaction between the quay wall and the extreme events. The results show that the proposed method, based on numerical modelling at different scales from macro to meso and to micro, allows for the identification of the best site-specific solutions, also for a location devoid of any wave measurement. In this light, the objectives of the paper are two-fold. First, they show the application of sea condition estimations through the use of wave hindcasted data in order to properly define the design wave conditions for a new harbour structure. Second, they present a new approach for investigating an innovative absorbing quay wall based on CFD modelling and the NewWave theory

Natural Metric for Quantum Information Theory

We study in detail a very natural metric for quantum states. This new proposal has two basic ingredients: entropy and purification. The metric for two mixed states is defined as the square root of the entropy of the average of representative purifications of those states. Some basic properties are analyzed and its relation with other distances is investigated. As an illustrative application, the proposed metric is evaluated for 1-qubit mixed states.Comment: v2: enlarged; presented at ISIT 2008 (Toronto

Werner states and the two-spinors Heisenberg anti-ferromagnet

We ascertain, following ideas of Arnesen, Bose, and Vedral concerning thermal entanglement [Phys. Rev. Lett. {\bf 87} (2001) 017901] and using the statistical tool called {\it entropic non-triviality} [Lamberti, Martin, Plastino, and Rosso, Physica A {\bf 334} (2004) 119], that there is a one to one correspondence between (i) the mixing coefficient $x$ of a Werner state, on the one hand, and (ii) the temperature $T$ of the one-dimensional Heisenberg two-spin chain with a magnetic field $B$ along the $z-$axis, on the other one. This is true for each value of $B$ below a certain critical value $B_c$. The pertinent mapping depends on the particular $B-$value one selects within such a range

Pseudo-ductile Failure of Adhesively Joined GFRP Beam-Column Connections:An Experimental and Numerical Investigation

Glass Fiber Reinforced Polymer (GFRP) I-beam-column adhesively bonded connections are tested under combined bending and shear. The special feature of the novel connection is the wrapping of the seat angles at the connection by a carbonfiber reinforced polymer (CFRP) fabric wrap. The wrap is primarily intended to alter the connection failure mode from brittle to pseudo-ductile, thus providing adequate warning of impending failure. Four moment resisting connection configurations are tested, including the reference configuration without the wrap. It is observed that the connection failure is initiated by the fracture of the adhesive, but the provision of the wrap, together with a steelseat angle, alters the failure mode from brittle to pseudoductile. The post-peak load deformation is achieved without a large drop in the resistance of the connection. On other hand, the connection with the wrapping and a GFRP seat angle can also change the failure mode to pseudo-ductile, but it could not be done without a large reduction in theconnectionresistanceafterthepeakload

CFD investigations of OXYFLUX device, an innovative wave pump technology for artificial downwelling of surface water

publisher: Elsevier articletitle: CFD investigations of OXYFLUX device, an innovative wave pump technology for artificial downwelling of surface water journaltitle: Applied Ocean Research articlelink: http://dx.doi.org/10.1016/j.apor.2016.10.002 content_type: article copyright: © 2016 Elsevier Ltd. All rights reserved