Numerical simulation of the sea bottom modifications behind a T-head groin

In this paper, we simulate the sea bottom modifications produced by the presence of a T-head groin. We present a simulation model of sea bottom modifications composed of two sub-models: a two-dimensional phase-resolving model that simulate the variation of the fluid dynamic variables inside the wave; a second sub-model to simulate the sea bottom modifications, in which the suspended sediment concentration is calculated by the wave-averaged advection-diffusion equation. The fluid motion equation and the concentration equation are expressed in a new contravariant formulation. The velocity fields from deep water up to just seaward of the surf-zone are simulated by a new integral contravariant form of the Fully Nonlinear Boussinesq Equations. The new integral form of the proposed continuity equation does not contain the dispersive term. The Nonlinear Shallow Water Equations, expressed in an integral contravariant form, are solved in order to simulate the breaking wave propagation. The momentum equation, integrated over the turbulent boundary layer, is solved to calculate the near-bed instantaneous flow velocity and the intra-wave hydrodynamic quantities. Starting from the contravariant formulation of the advection–diffusion equation for the suspended sediment concentration, it is possible to calculate the sea bottom modification. The advective sediment transport terms in the advection-diffusion equation are formulated according to a quasi-three-dimensional approach

3D numerical simulation of the interaction between waves and a T-head groin structure

The aim of coastal structures for the defense from erosion is to modify the hydrodynamic fields that would naturally occur with the wave motion, to produce zones of sedimentation of solid material, and to combat the recession of the coastline. T-head groin-shaped structures are among the most adopted in coastal engineering. The assessment of the effectiveness of such structures requires hydrodynamic study of the interaction between wave motion and the structure. Hydrodynamic phenomena induced by the interaction between wave motion and T-head groin structures have three-dimensionality features. The aim of the paper is to propose a new three-dimensional numerical model for the simulation of the hydrodynamic fields induced by the interaction between wave fields and coastal structures. The proposed model is designed to represent complex morphologies as well as coastal structures inside the domain. The numerical scheme solves the three-dimensional Navier-Stokes equations in a contravariant formulation, on a time-dependent coordinate system, in which the vertical coordinate varies over time to follow the free-surface elevation. The main innovative element of the paper consists in the proposal of a new numerical scheme that makes it possible to simulate flows around structures with sharp-cornered geometries. The proposed numerical model is validated against a well-known experimental test-case consisting in a wave train approaching a beach (non-parallel with the wave front), with the presence of a T-head groin structure. A detailed comparison between numerical and experimental results is shown

development of a dlp 3d printer for orthodontic applications

Abstract Recent advances in Additive Manufacturing (AM) technologies have allowed a widespread diffusion of their use in different fields. 3D printing is becoming commonplace for biomedical applications requiring the custom fabrication of prostheses and appliances fitting patient-specific anatomies. In this work, the feasibility of a vat photopolymerization technology, based on Digital Light Processing (DLP), has been investigated for the manufacturing of polymeric orthodontic appliances. A custom DLP 3D printer has been developed by exploiting an off-the-shelf digital projector, with the aim at studying the influence of printing parameters on the surface roughness. The feasibility of using Dental LT Clear resin, a biocompatible photopolymer specifically designed for SLA technology, has been finally verified

A Digital Process for Manufacturing Customized Trays for Dental-Whitening Treatments

This study presents an alternative process for designing and manufacturing customized trays for dental-whitening treatments. The process is based on a digitized approach consisting of three main stages: design of a reference model, its manufacturing by AM, and thermoforming of the tray. The aim of the study was to develop a high-performance tray, able to guarantee comfort, safety, and efficacy for whitening treatments. To evaluate the patient’s experience, some tests under real operating conditions were performed. Twenty people carried out a nighttime treatment of 14 days. Each patient was asked to assess the overall level of satisfaction and the comfort of the tray and its ability to retain the gel. Tooth whitening was also determined according to the VITAPAN scale. All patients involved in the study were satisfied and provided positive feedback about comfort and tightness of the tray. At the end of the treatment, 15 out of 20 patients achieved shade A1 on the VITAPAN scale. The mean improvement in color shades was about 7. These results confirmed the great potential of the proposed dental tray. Its use was proven to guarantee a high level of quality, flexibility, and customization of dental-whitening treatments, improving comfort, safety, and efficacy

Efficient District Heating in a Decarbonisation Perspective: A Case Study in Italy

The European and national regulations in the decarbonisation path towards 2050 promote district heating in achieving the goals of efficiency, energy sustainability, use of renewables, and reduction of fossil fuel use. Improved management and optimisation, use of RES, and waste heat/cold sources decrease the overall demand for primary energy, a condition that is further supported by building renovations and new construction of under (almost) zero energy buildings, with a foreseeable decrease in the temperature of domestic heating systems. Models for the simulation of efficient thermal networks were implemented and described in this paper, together with results from a real case study in Italy, i.e., University Campus of Parma. Activities include the creation and validation of calculation codes and specific models in the Modelica language (Dymola software), aimed at investigating stationary regimes and dynamic behaviour as well. An indirect heat exchange substation was coupled with a resistive-capacitive model, which describes the building behaviour and the thermal exchanges by the use of thermos-physical parameters. To optimise indoor comfort conditions and minimise consumption, dynamic simulations were carried out for different operating sets: modulating the supply temperature in the plant depending on external conditions (Scenario 4) decreases the supplied thermal energy (-2.34%) and heat losses (-8.91%), even if a lower temperature level results in higher electricity consumption for pumping (+12.96%), the total energy consumption is reduced by 1.41%. A simulation of the entire heating season was performed for the optimised scenario, combining benefits from turning off the supply in the case of no thermal demand (Scenario 3) and from the modulation of the supply temperature (Scenario 4), resulting in lower energy consumption (the thermal energy supplied by the power plant -3.54%, pumping +7.76%), operating costs (-2.40), and emissions (-3.02%). The energy balance ex-ante and ex-post deep renovation in a single user was then assessed, showing how lowering the network operating temperature at 55 degrees C decreases the supplied thermal energy (-22.38%) and heat losses (-22.11%) with a slightly higher pumping consumption (+3.28%), while maintaining good comfort conditions. These promising results are useful for evaluating the application of low-temperature operations to the existing district heating networks, especially for large interventions of building renovation, and confirm their potential contribution to the energy efficiency targets

Processability of Bulk Metallic Glasses

Microfluidic Shear Flow Instabilities in Injection Molded Glassy Metal are investigated. The formation of microfluidic shear flows instabilities involving the presence of different viscosities fluids has been observed in injection molded Bulk Metallic Glasses. The complex rheology of injection molded metastable glassy metal, which has been hypothesized to induce selective clustering of atoms of different steric hindrance, is discussed. Smaller Be, Cu and Ni atomsmay differently rearrange themselves in the bulk metal glassy super cooled liquids forming flow streams of lower viscosity. Segregation of atoms of different size could activate a variety of viscous flow instabilities such as folding and swirling. FEI Scios Dual-Beam Electron scanning and optical microscopy observations of a commercial liquid metal alloy (Zr44Ti11Cu10Ni10Be25) have been carried out. We discussed the influence of short-range order clusters distribution and its effect in locally induced shear flow instability and corrosion resistance

Additive manufacturing in bespoke interactive devices-a thematic analysis

Additive Manufacturing (AM) facilitates product development due to the various native advantages of AM when compared to traditional manufacturing processes. Efficiency, customisation, innovation, and ease of product modifications are a few advantages of AM. This manufacturing process can therefore be applied to fabricate customisable devices, such as bespoke interactive devices for rehabilitation purposes. In this context, a two-day workshop titled Design for Additive Manufacturing: Future Interactive Devices (DEFINED) was held to discuss the design for AM issues encountered in the development of an innovative bespoke controller and supporting platform, in a Virtual Reality (VR)-based environment, intended for people with limited dexterity in their hands. The workshop sessions were transcribed, and a thematic analysis was carried out to identify the main topics discussed. The themes were Additive Manufacturing, Generative Design Algorithms, User-Centred Design, Measurement Devices for Data Acquisition, Virtual Reality, Augmented Reality, and Haptics. These themes were then discussed in relation to the available literature. The main conclusion of this workshop was that a coherent design for AM tools is needed by designers to take AM considerations throughout the design process, since they lack the AM knowledge required to develop bespoke interactive devices