10 documents found, page 1 of 1
Comparison of RANS and LES turbulent flow models in a real stenosis
Lopes, D.; Puga, Hélder; Teixeira, J.; Lima, R.; Grilo, J.; Dueñas-Pamplona, J.; Ferrera, C.This study focuses on the performance of various turbulence models in predicting hemodynamic variables within a patient-specific geometry of the Brachiocephalic trunk exhibiting a severe stenosis. Numerical simulations employing Reynolds-averaged Navier-Stokes (RANS) and Large Eddy Simulation (LES) models were conducted, comparing four RANS with two LES models. Results indicated significant differences in turbu...
Casting A356+SiCp with ultrasonically treated melts: effect reinforcement and p...
Carneiro, Vitor H.; Grilo, J.; Puga, H.; Duarte, I.; Jesus, C.Low mass fractions (0.05 wt%) of SiC micro sized particles have been added to an A356 melt and dispersed by ultrasonic vibration to study their impact on the microstructural morphology of cast samples. It is shown that the ultrasonic melt treatment at 680°C can promote a homogenizeddistribution of the reinforcement while also degassing the melt and induces a moderate grain refinement. Even though SiC may act as...
Effect of hybrid ultrasonic and mechanical stirring on the distribution of m-Si...
Grilo, J.; Puga, Hélder; Carneiro, V. H.; Tohidi, Shafagh Dinparast; Barbosa, Flávia Vieira; Teixeira, J. CarlosThe present study details the micro-scale silicon carbide particle (m-SiCp) homogeneous distribution in an A356 alloy through hybrid ultrasonic-stirring melt treatment under different operation conditions. Ultrasonically excited fluids were studied by particle image velocimetry to estimate the efficiency of the acoustic streaming in different distances to the sonotrode. Distinct particle approaches to introduce...
High-performance μ-thermoelectric device based on Bi2Te3/Sb2Te3 p-n junctions
Vieira, Eliana Maria Fernandes; Pires, A. L.; Silva, José Pedro Basto; Magalhães, V. H.; Grilo, J.; Brito, F.P.; Silva, M. F.; Pereira, A. M.A flexible and ultralight planar thermoelectric generator based on 15 thermocouples composed of n-type bismuth telluride (Bi2Te3) and p-type antimony telluride (Sb2Te3) legs (each with 400 nm thick) connected in series, on 25 μm thick Kapton substrate, was fabricated with impressive power factor values of 2.7 and 0.8 mW K-2 m-1 (at 298 K) for Bi2Te3 and Sb2Te3 films, respectively. The p-n junction thermoelectri...
Physical and chemical assessment of lime–metakaolin mortars: Influence of binde...
Gameiro, A.; Santos Silva, A.; Faria Rodrigues, P.; Grilo, J.; Branco, T.; Veiga, M. R.; Velosa, A.This work evaluates the influence of binder:aggregate ratio on the mineralogical and mechanical properties of air lime–metakaolin mortars. Mineralogical analysis showed that binder:aggregate ratio affects the extent of carbonation and pozzolanic reactions with curing. The pozzolanic reaction occurs mostly at lower curing times (28 days), while, at higher curing ages, carbonation reaction is mostly dominant. The...
New natural hydraulic lime mortars – Physical and microstructural properties in...
Grilo, J.; Faria Rodrigues, P.; Veiga, M. R.; Santos Silva, A.; Silva, V.; Velosa, A.The new version of EN 459-1 standard for building limes redefined the classes of hydraulic limes and made the producers reformulate or reclassify their natural hydraulic limes. This work evaluates the mechanical, physical and microstructural behavior of mortars formulated with a recently produced natural hydraulic lime NHL3.5 that conforms to EN 459-1, submitted to natural marine environment, humid and standard...
Long-term behavior of lime–metakaolin pastes at ambient temperature and humid c...
Santos Silva, A.; Gameiro, A.; Grilo, J.; Veiga, M. R.; Velosa, A.This paper presents the reaction behavior of lime and metakaolin (MK) pastes submitted to long term aging at ambient temperature and relative humidity of 95 ± 5%. The results presented are the basis for an extensive research pointing towards the formulation of lime based mortars for conservation of historic buildings, namely in humid environments. MK, when mixed with calcium hydroxide, in the presence of water,...
Mechanical and mineralogical properties of natural hydraulic lime-metakaolin mo...
Grilo, J.; Santos Silva, A.; Faria Rodrigues, P.; Gameiro, A.; Veiga, M. R.; Velosa, A.This paper investigates the mechanical and mineralogical characteristics of natural hydraulic lime NHL3.5 (NHL) mortars with different% of lime replacement by metakaolin (MK) under different laboratory and natural marine curing conditions. Tests were conducted at different curing ages, using compressive and flexural strength tests and thermogravimetric and X-ray diffraction techniques. NHL mortars cured at high...
Influence of the particle size and animal slurry type on the potential of nitro...
Fangueiro, D.; Gusmão, M.; Grilo, J.; Vasconcelos, E.; Cabral, F.Animal manures are rich in organic matter and nutrients, namely nitrogen (N) and, consequently, widely applied to soil as organic fertilizers. However, a large part of the nitrogen contained in animal manures is in the organic form and so not directly available for plants. Indeed, organic N has to be mineralized prior to plant uptake (Rees and Castle, 2002). Several manure characteristics as the C:N ratio (Chad...
Proportion, composition and potencial N mineralisation of particle size fractio...
Fangueiro, D.; Gusmão, M.; Grilo, J.; Porfirio, G.; Vasconcelos, E.; Cabral, F.Mechanical slurry separation is a useful technology for slurry management on farms. The characteristics of the fractions obtained depend on the separation efficiency and on the characteristics of the original slurry. In the present work, three types of slurry e pig, cow and duck e were separated into 4 particle size fractions. The proportion, composition in terms of carbon and nutrients as nitrogen (N) phosphor...