Resumo em Inglês:

ABSTRACT Improving natural ventilation during animal transportation is a promising approach for promoting animal well-being and reducing losses. The objective of this study was to evaluate in silico the efficiency of devices (airfoils and deflectors) used for cooling trailers during the transportation of pigs. Device performance was assessed using computational fluid dynamics (CFD) simulations and 3D modeling of the enthalpy profile of a trailer, and adaptive mesh generation was employed to construct a computational mesh. Turbulence treatments were performed using RANS model and k-ω SST models. The results revealed that compared with the conditions observed in commercial transportation, the use of an airfoil increased the airflow and reduced the enthalpy within the assessed trailer (-5.4%). Likewise, the use of deflectors resulted in a reduction in enthalpy (-3.04%), although their use led to a translocation of the thermal core to the front region of the upper floor of the trailer. Nevertheless, the use deflectors has been proven to be more efficient when combined with an airfoil. In conclusion, the results obtained from our CFD simulations provide evidence to indicate that it is possible to optimize ventilation within transport containers using aerodynamic devices.

Resumo em Inglês:

ABSTRACT Cylindrical steel silos with flat bottoms are widely used in agriculture and industry for storing granular materials. While research has advanced our understanding of pressure on silo walls, accurate prediction, especially during the dynamic filling and discharge phases, remains a challenge. This study presents a finite element (FE) analysis of pressure distribution in a model cylindrical steel silo with a flat bottom, investigating the influence of the height-to-diameter (H/D) ratio. The numerical results were validated against experimental data from a pilot-scale test facility storing corn. Material properties were determined through laboratory experiments, with mechanical properties obtained from literature. An arbitrary Lagrangian formulation was employed for the FE calculations. The FE results showed good agreement with experimental data for static pressure distribution on the silo wall across all H/D ratios analyzed. While the patterns of dynamic pressure curves were similar, the FE-predicted magnitudes were lower than those observed experimentally. Notably, the simulations captured significant pressure fluctuations during silo discharge.

Resumo em Inglês:

ABSTRACT Mathematical models to determine external pressure coefficients (Cpe) in conical silo roofs are scarce in silo design standards and scientific papers. These coefficients are dimensionless and are influenced by Reynolds number, air viscosity, geometry, and surface roughness of the material used in the structure. Pressure coefficients in conical roofs vary in the circumferential and meridional directions. Cpe values are essential in designing these structures to determine the pressures that arise from wind action. However, the scarcity of mathematical models for calculating external pressure coefficients in conical silo roofs made us conduct harmonic regression analyses to fit mathematical models based on experimental data developed in wind tunnels. Model fitting to experimental data had coefficients of variation lower than 10% in 87.5% (7/8) of the analyzed levels. These models are recommended for cases where wind gust duration does not exceed 3 seconds.

Resumo em Inglês:

ABSTRACT Timber bridges in Brazil, intended for rural roads and rural areas, present several problems due to the lack of design, structural calculation, and periodic maintenance by municipal administrations. This study evaluated a total of 10 timber bridges with a deck of sawn planks connected by nails to natural round beams, aiming to identify their main pathologies and provide minimum pre-sizing values for the used sections. The bridges were inspected on-site to measure the parts and identify the main problems. Subsequently, based on the Manual de Projeto e Construção de Pontes de Madeira and ABNT NBR 7190-1 (2022), we verified whether the diameter of the round beams found on site was adequate from the point of view of structural sizing using an Excel spreadsheet. Most of the analyzed bridges had spans of up to 15 m and problems related to the degradation of the timber and metal connections, reducing their useful life. As a result, the main construction recommendations for bridges are the use of timber treated with chromated copper arsenate (CCA) and galvanized connections to prevent corrosion. The use of the proposed pre-sizing tables is recommended to ensure minimum calculation values, considering the design vehicle classes and the minimum dimensions for the timber sections. This study aims to guide Brazilian municipal administrations and other interested parties in the construction of timber bridges for rural areas, obtaining safe, low-cost, and highly durable structures.