The non-Newtonian Carreau fluid model is a suitable model for pseudoplastic fluids and can be used to characterize fluids not so different from biological fluids, such as the blood, and fluids involved in geological processes, such as lava and magma. These fluids are frequently conveyed by complex flow structures, which consist of a network of channels that allow the fluid to flow from one place (source or sink) to a variety of locations or vice versa. These flow networks are not randomly arranged but show self-similarity at different spatial scales. Our work focuses on the design of self-similar branched flow networks that look the same on any scale. The flow is incompressible and stationary with a viscosity following the Carreau model, which is important for the study of complex flow systems. The flow division ratios, the flow resistances at different scales, and the geometric size ratios for maximum flow access are studied, based on Computational Fluid Dynamics (CFD). A special emphasis is placed on investigating the possible incidence of flow asymmetry in these symmetric networks. Our results show that asymmetries may occur for both Newtonian and non-Newtonian fluids and shear-thinning fluids most affect performance results. The lowest flow resistance occurs when the diameters of the parent and daughter ducts are equal, and the more uniform distribution of flow resistance occurs for a ratio between the diameters of the parent and daughter ducts equal to 0.75. Resistances for non-Newtonian fluids are 4.8 to 5.6 times greater than for Newtonian fluids at Reynolds numbers of 100 and 250, respectively. For the design of engineering systems and the assessment of biological systems, it is recommended that the findings presented are taken into account.

This study probabilistically assesses magma ascent by modeling dike propagation as a fully coupled fluid-flow, thermo-mechanical problem, explicitly accounting for the stochastic heterogeneity of the crustal host rock. We study felsic (rhyolite) lava flow and two distinct basaltic feeding regimes that correspond to the conditions necessary to produce the contrasting pāhoehoe and ʻaʻā surface morphologies. Basaltic dikes demonstrate high propagation efficiency to the surface (pāhoehoe-feeding regime 99.5%; ʻaʻā-feeding regime 97.5%), whereas rhyolite dikes have an 89% failure rate, attributed to significant friction. Both regimes represent distinct constructal approaches aimed at maximizing flow persistence. The pāhoehoe-feeding regime is a thermally regulated, stable design characterized by low-velocity, cooling-dominated dynamics. Its slow, persistent flow allows for significant conductive heating of the surrounding rock wall, creating an efficient, pre-heated thermal conduit. In contrast, the ʻaʻā-feeding regime is a mechanically dominated design governed by high-velocity, stochastic dynamics. This morphology is driven by forceful flow, and its thermal budget is supplemented by intense viscous dissipation (internal friction). Rhyolite magma flow fails upon losing constructal viability, driven by a coupled mechanical–thermal cascade. The sequence begins when a mechanical barrier halts the magma velocity, which triggers a freezing event and leads to permanent arrest.

This study investigates the asymmetric effects applying heat transfer as a diagnostic tool in dendritic networks with symmetrical branching, characterized by the geometric property of self-similarity. Using a Computational Fluid Dynamics (CFD) model, we analyze five structural isomers of a three-level dichotomous branching network to evaluate the relationship between fluid dynamics, heat transfer, and geometric configuration. The main constraints are geometrical; that is, the volume at each branching level remains constant, and homothetic relationships respect the Hess–Murray law both for diameters and angles between sister tubes. The model considers an incompressible and stationary Newtonian fluid flow with Reynolds numbers ranging from 10 to 2000 and heat transfer in the range 1 to 1000 W/m². Our results show that significant asymmetries in flow distribution and temperature profiles emerge in these symmetric structures, primarily due to the successive alignment of tubes between different branching levels. We found that the isomer with the lowest pressure drop is not the same as the one providing the most uniform flow distribution. Crucially, thermal analysis proves to be more sensitive than fluid dynamic analysis for detecting flow asymmetries, particularly at low Reynolds numbers less than 50 and q″ = 1000 W/m². While heat transfer does not significantly alter the fluid dynamic asymmetry, its application as a diagnostic tool for identifying flow asymmetries is effective and crucial for such purposes.

Este artigo teve como objetivo identificar os aspectos e estimar os impactos financeiro de um acidente de trabalho com afastamento em uma concessionária de veículos pesados. Para o desenvolvimento deste trabalho, foram aplicadas as ferramentas de qualidade como o Diagrama de Ishikawa e 5 Porquês. Também foram utilizadas as ferramentas associadas à Saúde e Segurança como a Pirâmide de Segurança e a análise de ocorrência de desvio por meio da Curva de Bradley. Foram avaliados e estudados os dados históricos de acidentes com afastamento de uma oficina de veículos pesados, no qual o período analisado foi de 60 meses entre janeiro de 2019 a dezembro de 2023. Buscou-se realizar uma avaliação detalhada dos setores com maior incidência de acidentes da empresa pesquisada. Com base nos aspectos e dados levantados, foi elaborado um levantamento dos principais custos relacionados aos acidentes de trabalho. Entre os resultados destaca-se o impacto financeiro diário de R$ 1.647,91 ou R$ 196.450,00 relacionado a 120 dias de afastamento de um colaborador acidentado. Além disso, com a evolução da maturidade de segurança, busca-se a meta acidente zero, o que acaba refletindo em ganhos operacionais sem perda de Horas Homem Trabalhadas (HHT), melhorando a imagem da organização perante a sociedade, maior capacidade de atendimento aos clientes e melhor resultado financeiro.

This study applies the Constructal Design method to the geometric optimization of a branched symmetric concentration divider for calibrating ultrasound devices used to monitor tumor response with dynamic contrast. Accurate calibration ensures image quality and diagnostic reliability. The geometry consists of a three-dimensional, tree-shaped flow network with two inlets and three outlets, where inlet 1 carries water containing contrast particles, while inlet 2 carries only water. Laminar flow simulations are performed using Computational Fluid Dynamics (CFD) with Ansys Fluent, assuming no-slip wall conditions and zero-pressure outlets. The analysis investigates the effects of the inlet velocity ratio, the diameter ratio, and the vertical positions of the central outlet and inlet tubes, while keeping the total volume and inlet diameter constant. Additionally, velocity, pressure, particle distributions, flow partition ratio, and hydraulic resistance are evaluated. Results show nearly linear concentration responses among the outlets (100%, 50%, and 0%) when the device approaches geometric symmetry with equal inlet velocities, demonstrating efficient control of flow splitting. Although the diameter ratio imposes a trade-off with hydraulic resistance, geometric symmetry combined with Constructal Design promotes improved flow uniformity and enhanced performance, with potential applications in microfluidic mixers that require precise intermediate concentrations.

Com intuito de obter bons resultados em relação à concorrência, as empresas têm estimulado a competitividade nos diversos segmentos industriais, desenvolvendo formas de tornar suas operações e processos produtivos cada vez mais eficientes. Desta forma, este trabalho teve como objetivo reduzir os tempos de processo e o consumo de energia elétrica dos misturadores de aditivo e polímero. Foram utilizados fluxogramas para o mapeamento do processo de aditivação e a ferramenta 5W2H, para desenvolver um plano de ação eficiente na implementação das propostas de melhorias no sistema de automação dos misturadores de aditivo e polímero, reduzindo os tempos de operação dos equipamentos e gerando economia, tanto de energia elétrica quanto financeira. Nesse sentido, este trabalho apresenta um estudo de caso quantitativo e qualitativo, com natureza de pesquisa aplicada envolvendo um caso real, com interesses locais e com objetivos específicos. Após a implementação das melhorias, houve diminuição no tempo total de processo de cem minutos (1h40min), redução no tempo de utilização da água gelada de cento e setenta minutos (2h50min) e diminuição no tempo de operação dos agitadores de oitenta minutos (1h20min) gerando uma economia de R$ 6.011,60 por dia com energia elétrica, que maximizada representa R$ 2.194.234,00 por ano. Desta maneira, o trabalho contribuiu para a geração de resultados positivos no processo, permitindo ganhos de produtividade e redução de custos, com oportunidade de alcançar os mesmos resultados em outros sistemas automatizados assim como em outras unidades industriais.