Artigos de Revista

The interface between the main channel and the floodplain of a compound channel is often populated by trees or buildings that normally remain emergent during floods. This study investigates how drag on an emergent cylinder is affected by the shear flow that develops at the interface. The experimental set-up features a circular cylinder at the interface of a straight compound channel under uniform flow conditions. The integral form of the equation of conservation of momentum was used to calculate the magnitude and direction of the time-averaged drag force per unit submerged-length of the cylinder. All terms were experimentally determined, except for those associated with fluid interaction with the cylinder. The same method was also applied to a cylinder under symmetrical flow conditions. It is concluded that the existence of the shear layer leads to an asymmetrical drag force and to a reduced drag coefficient.

This paper presents the development and application of a comprehensive methodology for the systematic water balance calculation in collective irrigation systems (CIS), applicable to pressurized pipelines or open canals. Existing approaches focus solely on the assessment the water resources use efficiency of CIS single components (e.g., leakage in some canal reaches), without a system-wide approach. A water balance approach allows accounting for the different system volume inputs (i.e., water abstraction, imported water, water volume due to precipitation or surface runoff), authorized and non-authorized consumptions and water losses either in canal, mixed or pressurized CIS, which has never been presented in literature. The proposed methodology allows the assessment of different water loss components (i.e., evaporation losses, unauthorized uses, metering errors, leakage and discharges) and the calculation of water loss performance indicators that allow the identification of the main problems in terms of water losses and provides guidance about measures to control water losses. Although based on the existing and consolidated water balance schemes specifically developed for urban water supply systems, the proposed methodology includes novel components in terms of system input volume, authorized consumption and water loss that are specific of CIS. The methodology is tested and applied to a mixed collective irrigation system. Results show that the water losses due to discharges in canal systems can be one of the most relevant component of the non-revenue water, representing approximately half of its total volume, followed by leakage in canals and metering errors. These results highlight the importance of improving daily operation of these systems and also rehabilitating ageing infrastructures.

Masonry arch bridges form a significant portion of the European transport infrastructure network. Many of these bridges are relatively old but still in service. Increasing vehicle loads and speeds have highlighted the need for reliable estimates of their service condition. Past research demonstrated that load-carrying capacity of a masonry arch bridge is a function of the soil response. However, today, the approaches used for the simulation of soil in masonry arch bridges are over-simplistic and most of them do not take into account the soil-structure interaction phenomena. This paper presents a novel modelling approach, based on the discrete element method, for the simulation of backfill material in masonry arch bridges. According to the method, bricks in the barrel vault are simulated as an assembly of distinct blocks separated by zero thickness interfaces at each mortar joint. Backfill is represented as an assemblage of densely packed discrete irregular deformable particles, here called ‘‘inner-backfill particles”. A series of computational models were developed and their results are compared against full-scale experimental test results. A good agreement between the experimental and the numerical results was obtained which demonstrates the huge potential of this novel modelling approach. One of the major advantages of the proposed approach is its ability to simulate the initiation and propagation of cracking in the backfill and arch ring with the application of the external load. It is envisaged that the current modelling approach can be used by bridge assessment engineers for understanding soil pressures and load distribution on the backfill and arch ring and thus develop serviceability criteria for masonry arch bridges of their care.

Mechanical constraints have a non-negligible influence in the motion of oscillating wave surge converter (OWSC) devices. The key novelty of this paper is a numerical simulation tool for OWSCs that does not neglect or significantly compromise mechanical constraints such as hydraulic power take-off (PTO) system, revolute joints and frictional contacts among components. The paper is aimed at presenting the key components of the numerical simulation tool and at validating it with laboratory data featuring an OWSC with mechanical constraints under regular and irregular waves. It is based on the implementation of the multibody solver of Project Chrono under the Smoothed Particle Hydrodynamics (SPH) model of DualSPHysics, where the SPH solver resolves the interaction between wave and flap and the multibody solver resolves the interaction between flap and mechanical constraints. Comparison between numerical results and experimental data show that the numerical simulation tool properly predicts the dynamics of the OWSC. Furthermore, in what concerns hydrodynamics of the near-flap flow, the computed and measured free-surface elevations and phase-averaged flow field show reasonable agreement. Once properly validated, the numerical simulation tool is then applied to study the influence of several mechanical constraints, PTO damping characteristics and flap inertia on the hydrodynamic of the OWSC. The viability of OWSC design solutions based on the developed numerical simulation tool is emphasised, in view of its performance in the test cases to which it was subjected.

Knowledge of forces due to the action of waves on submarine outfalls composed by a pipe and stabilizing concrete weights, considering the wave propagation direction to the outfalls, is essential to their design. 3D numerical models based on RANS-VoF (Reynolds-Average-Navier-Stokes Volume-of-Fluid) are able to estimate forces on the pipe and weights. The present study aims to simulate a submarine outfall with stabilizing concrete weights at 1:15 scale which was previously tested in the 3D Shallow Water Basin at the Danish Hydraulics Institute (DHI) to analyse the influence of the direction of the incident wave and the distance from the pipe to the bottom on the outfall forces. In this study, numerical results are compared with experimental ones for waves with four different amplitudes and with wave incidence perpendicular to the outfall. The use of k-? SST turbulence model led to good agreement between numerical drag and lift forces and experimental ones, with a mean difference of 8.9 and 7.6%, respectively.

No presente artigo aborda-se a relação entre o interior doméstico e os respectivos vãos de janela, considerados estes vãos como importantes elementos de construção, acabamento, e qualidade arquitectónica do interior doméstico. Inicia-se a reflexão com a consideração das janelas como elementos de composição dos alçados/volumetrias, mas também como elementos multifuncionais e de composição do interior doméstico; desenvolve-se, depois, a temática das janelas domésticas como elementos de composição dos alçados/volumetrias; seguem-se alguns comentários sobre a multifuncionalidade das janelas domésticas; e conclui-se com uma reflexão sobre as janelas como elementos específicos de composição do interior doméstico.

This paper is built around a research project developed with the support of the Regional Planning Authority of the Algarve Region in Portugal which assessed mobility patterns covering all modes of transport using heterogeneous data sources (time-series data). Data mining techniques helped to identify limitations in some data sets. The econometric analysis showed that integrated autoregressive models and moving averages for series with seasonality were successful in the prediction of passenger flows using time-series data gathered by the regional authority from transport operators and other entities. Results from the analysis are useful to support a strategy to reverse current trends on continued car growth (along with public transport decrease) and to devise policy measures to enable a sustainable mobility path towards decarbonisation and social equity goals until 2030.

O risco refere-se à probabilidade de ocorrerem danos causados pela manifestação de um determinado perigo, sendo função da perigosidade, da exposição (de pessoas e bens) e da vulnerabilidade dos elementos expostos face a esse perigo.Um componente essencial da avaliação do risco è a análise da perigosidade associada aos perigos identificados num dado território, sejam de origem natural ou decorrentes da ação humana. Outro componente essencial é a análise dos elementos (pessoas e bens) expostos aos perigos, bem como as características que contribuem para a suavulnerabilidade - ou a sua resiliência em situação de acidente grave ou de catástrofe. Nesta comunicação dá-se conta de alguns estudos desenvolvidos pelo LNEC nos domínios da avaliação da perigosidade e da vulnerabilidade sísmica das construções, da perigosidade de agitação costeira e risco de galgamentos costeiros e da avaliação da vulnerabilidade de edifícios aos incêndios florestais.

O artigo aborda a noção de ‘bairro’ como um importante recurso simbólico da construção do imaginário de Lisboa na atualidade, não só confirmando a continuidade transformativa de que a cidade é “uma cidade de bairros”, mas também influenciando a realidade quotidiana destes lugares-bairro. Para o efeito, realiza-se uma revisitação da noção de bairro na literatura. Seguidamente exemplifica-se, através de determinados casos, alguns recursos à noção de bairro e respetiva resignificação do conceito, procurando observar algumas das problemáticas contemporâneas da cidade e, como tal, dos seus bairros.