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Due to the anatomical complexity of the aortic arch for the development of stent-grafts for total repair, this region remains without a validated and routinely used endovascular option. In this work, a modular stent-graft for aneurysms that covers all aortic arch zones, proposed by us and previously structurally evaluated, was evaluated from the point of view of haemodynamics using fluid-structural numerical simulations. Blood was assumed to be non-Newtonian shear-thinning using the Carreau model, and the arterial wall was assumed to be anisotropic hyperelastic using the Holzapfel model. Nitinol and expanded polytetrafluoroethylene (PTFE-e) were used as materials for the stents and the graft, respectively. Nitinol was modelled as a superelastic material with shape memory by the Auricchio model, and PTFE-e was modelled as an isotropic linear elastic material. To validate the numerical model, a silicone model representative of the aneurysmal aorta was subjected to tests on an experimental bench representative of the circulatory system. The numerical results showed that the stent-graft restored flow behaviour, making it less oscillatory, but increasing the strain rate, turbulence kinetic energy, and viscosity compared to the pathological case. Taking the mean of the entire cycle, the increase in turbulence kinetic energy was 198.82% in the brachiocephalic trunk, 144.63% in the left common carotid artery and 284.03% in the left subclavian artery after stent-graft implantation. Based on wall shear stress parameters, it was possible to identify that the internal branches of the stent-graft and the stent-graft fixation sites in the artery were the most favourable regions for the deposition and accumulation of thrombus. In these regions, the oscillating shear index reached the maximum value of 0.5 and the time-averaged wall shear stress was close to zero, which led the relative residence time to reach values above 15 Pa-1. The stent-graft was able to preserve flow in the supra-aortic branches.

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Mitigating Urban Heat Island (UHI) intensity in cities through adaptative strategies has become an urgent need, as UHI are also exacerbated by climate change impacts imputable to anthropogenic actions. This study addresses the need for reliable simulation models to analyze outdoor thermal comfort (OTC) in future or alternative scenarios. The aim of the present study is to contribute to the validation of CFD urban microclimate simulations by employing intra-urban canyon transects as an alternative or a complementary approach to fixed stations. To accomplish this, we developed a cost-effective monitoring unit to carry out transects on a pre-defined route (1), devised the area of interest (2), elaborated a simulation model in ENVI-met (3), and proposed different validation methods for comparative analyses (4). Results indicate that temporal validated simulation tended to underestimate thermal indices in the morning and night and overestimate them in the afternoon, while spatio-temporal validation under a human-centric comfort approach via wearable sensing notably improved accuracy. Moderate to very strong agreement between simulation and measurement data in summer (Willmot's d ~ 0.70, d ~ 0.81) and very strong agreement in winter (d ~ 0.79, d ~ 0.96), with low error magnitudes in summer (RMSE ~ 0.91℃ and 9.59%, MBE ~ 0.23℃ and 9.10%) have been found. In winter, such figures were RMSE ~ 0.71℃ and 3.51%, MBE ~ 0.00℃ and 0.98%, for the spatio-temporal validated model. This research contributes to enhancing the reliability of relatively affordable CFD urban microclimate simulations, supporting its scale up for policymakers in implementing effective strategies for OTC.

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The automotive industry continuously enhances vehicle design to meet the growing demand for more efficient vehicles. Computational design and numerical simulation are essential tools for developing concept cars with lower carbon emissions and reduced costs. Underground roads are proposed as an attractive alternative for reducing surface congestion, improving traffic flow, reducing travel times and minimizing noise pollution in urban areas, creating a quieter and more livable environment for residents. In this context, a concept car body design for underground tunnels was proposed, inspired by the mako shark shape due to its exceptional operational kinetic qualities. The proposed biomimetic-based method using computational fluid dynamics for engineering design includes an iterative process and car body optimization in terms of lift and drag performance. A mesh sensitivity and convergence analysis was performed in order to ensure the reliability of numerical results. The unique surface shape of the shark enabled remarkable aerodynamic performance for the concept car, achieving a drag coefficient value of 0.28. The addition of an aerodynamic diffuser improved downforce by reducing 58% of the lift coefficient to a final value of 0.02. Benchmark validation was carried out using reported results from sources available in the literature. The proposed biomimetic design process based on computational fluid modeling reduces the time and resources required to create new concept car models. This approach helps to achieve efficient automotive solutions with low aerodynamic drag for a low-carbon future.

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A conventional hydrocyclones is a versatile equipment with a high processing capacity and low maintenance cost. Currently, several studies aim to alter the typical structure of the conventional hydrocyclone in order to modify its performance and purpose. For this, filtering hydrocyclones have emerged, where a porous membrane replaces the conic or cylindrical wall. During the operation of this equipment, in addition to the traditionally observed streams (feed, underflow, and overflow), there is a liquid stream resulting from the filtration process, commonly referred to as filtrate. This work proposes to numerically investigate the solid particle/liquid water separation process in a filtering hydrocyclone using the commercial software Ansys CFX® 15.0. The proposed mathematical model for the study considers three-dimensional, steady state and turbulent flow, using the Eulerian-Eulerian approach and the Shear Stress Transport (SST) turbulence model. This study presents and analyzes the volume fraction, velocity, and pressure fields, along with flowlines and velocity profiles. The results indicate that the proposed model effectively captures the fluid dynamic behavior within the filtering hydrocyclone, highlighting higher pressures near the porous membrane and a higher concentration of solid particles in the conical region, with water being more concentrated in the cylindrical part of the hydrocyclone. Additionally, the findings show that the volumetric flow rate of the filtrate significantly influences the internal flow dynamics, with conventional hydrocyclones demonstrating higher pressure gradients compared to the proposed filtering hydrocyclone.

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This study conducts a numerical comparison of the thermal performance of three distinct working fluids (pure water, TiO2, and SiO2 water-based nanofluids) within an evacuated tube solar collector using Computational Fluid Dynamics. The study evaluates thermohydraulic performance alongside global and local entropy generation rates, while considering variations in solar radiation values and inlet mass flow rates. Results indicate that nanofluids demonstrate superior performance under low solar radiation, exhibiting higher outlet temperatures, velocities, thermal efficiency, and exergy efficiency compared to pure water. However, at the higher solar radiation level, the efficiency of SiO2 water-based nanofluid diminishes due to its impact on specific heat. Furthermore, the entropy generation analysis reveals significant reductions with TiO2 water-based nanofluid in all the phenomena considered (up to 79 %). The SiO2 nanofluid performance aligns closely with pure water under high radiation value. This investigation offers valuable insights into the utilization of nanofluids in solar collectors across diverse operating conditions, emphasizing their pivotal role in enhancing overall performance.

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Ascending aortic aneurysm (AAoA) is a silent disease with high mortality; however, the factors associated with a worse prognosis are not completely understood. The objective of this observational, longitudinal, single-center study was to identify the hemodynamic patterns and their influence on AAoA growth using computational fluid dynamics (CFD), focusing on the effects of geometrical variations on aortic hemodynamics. Personalized anatomic models were obtained from angiotomography scans of 30 patients in two different years (with intervals of one to three years between them), of which 16 (53%) showed aneurysm growth (defined as an increase in the ascending aorta volume by 5% or more). Numerically determined velocity and pressure fields were compared with the outcome of aneurysm growth. Through a statistical analysis, hemodynamic characteristics were found to be associated with aneurysm growth: average and maximum high pressure (superior to 100 Pa); average and maximum high wall shear stress (superior to 7 Pa) combined with high pressure (>100 Pa); and stress load over time (maximum pressure multiplied by the time interval between the exams). This study provides insights into a worse prognosis of this serious disease and may collaborate for the expansion of knowledge about mechanobiology in the progression of AAoA.

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AIM: To compare eight large- and low-tapered heat-treated reciprocating instruments regarding their design, metallurgy, mechanical properties, and irrigation flow through an in silico model. METHODOLOGY: A total of 472 new 25-mm E-Flex Rex (25/.04 and 25/.06), Excalibur (25/.05), Procodile (25/.06), Reciproc Blue R25 (25/.08v), WaveOne Gold Primary (25/.07v), and Univy Sense (25/.04 and 25/.06) instruments were evaluated regarding their design (stereomicroscopy, scanning electron microscopy, and 3D surface scanning), metallurgy (energy-dispersive X-ray spectroscopy and differential scanning calorimetry), and mechanical performance (cyclic fatigue, torsional resistance, cutting ability, bending and buckling resistance). Computational fluid dynamics assessment was also conducted to determine the irrigation flow pattern, apical pressure, and wall shear stress in simulated canal preparations. Kruskal-Wallis and one-way anova post hoc Tukey tests were used for statistical comparisons (α = 5%). RESULTS: Instruments presented variations in blade numbers, helical angles, and tip designs, with all featuring non-active tips, symmetrical blades, and equiatomic nickel-titanium ratios. Cross-sectional designs exhibited an S-shaped geometry, except for WaveOne Gold. Univy 25/.04 and Reciproc Blue displayed the smallest and largest core diameters at D3. Univy 25/.04 and E-Flex Rec 25/.04 demonstrated the longest time to fracture (p < .05). Reciproc Blue and Univy 25/.04 exhibited the highest and lowest torque to fracture, respectively (p < .05). Univy 25/.04 and Reciproc Blue had the highest rotation angles, whilst E-Flex Rec 25/.06 showed the lowest angle (p < .05). The better cutting ability was observed with E-Flex Rec 25/.06, Procodile, Excalibur, and Reciproc Blue (p > .05). Reciproc R25 and E-Flex Rec showed the highest buckling resistance values (p < .05), with WaveOne Gold being the least flexible instrument. The impact of instruments' size and taper on wall shear stress and apical pressure did not follow a distinct pattern, although Univy 25/.04 and E-Flex Rec 25/.06 yielded the highest and lowest values for both parameters, respectively. CONCLUSIONS: Low-tapered reciprocating instruments exhibit increased flexibility, higher time to fracture, and greater angles of rotation, coupled with reduced maximum bending loads and buckling strength compared to large-tapered instruments. Nevertheless, low-tapered systems also exhibit lower maximum torque to fracture and inferior cutting ability, contributing to a narrower apical canal enlargement that may compromise the penetration of irrigants in that region.

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Solar energy capacity has increased significantly globally, with values above 800 GW produced by different systems. Among these, PVT panels can generate either electricity, heat, or both. As these systems present various issues associated with excessive temperature increases, cooling systems have been developed to control the temperature using fluids such as water. The article uses previous data from the Technologic Institute of Sonora, which analyzed various cooling device configurations and selected the best two options (B1 and B4) based on the panel efficiency. Using the boundary conditions and the predicted streamlines, a simulation was made in CFD programs, determining the correct parameters to replicate the system fluid dynamics. Several simulations were carried out using different turbulence models. After comparing the temperature contour diagram and the streamline, it was obtained that the k-ω turbulence model best describes the fluid's behavior. The transient analysis simulations allow us to determine that the B1 configuration delivers the best cooling effect as it presents the most homogeneous temperature profile. BIAS and RMSE were calculated to validate and contrast the results obtained experimentally, obtaining values of 0.8675 and 1.8981, respectively.

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Floating treatment islands (FTIs) offer effective solutions for stormwater management, providing flood attenuation and pollutant removal capabilities. However, there remains a knowledge gap concerning their performance, specifically in terms of pollutant removal and sediment deposition. To address this gap, the present study employs computational fluid dynamics (CFD) modeling to investigate the intricate interactions within FTI systems. Various FTI configurations are analyzed, considering mass removal through FTIs and sediment deposition, the first time where these two processes were considered together in a CFD environment. The findings demonstrate that FTIs have a significant influence on flow patterns and mass removal. Notably, FTIs enhance mass removal compared to the control case, with larger sediment particles exhibiting higher removal rates. The correlation between the short-circuit index and sedimentation in FTI ponds highlights the potential of FTIs as indicators of treatment efficiency. Furthermore, the study focuses on mass removal exclusively through the FTI root zones. The positioning of FTIs within the pond has a considerable impact, resulting in differences of up to 20% in mass removal. Moreover, the FTI configuration exerts a more pronounced influence on mass removal through FTIs than through sediment deposition alone. In cases where both processes occur simultaneously, the presence of FTIs lead to higher mass removal, primarily attributed to the FTIs themselves, particularly in the initial segment. Remarkably, certain FTI configurations enable mass removal exceeding 70% for large sediment particles, even with a pond length less than half of the original.

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OBJECTIVE AND SIGNIFICANCE: This research aims to design and develop a pilot plant-type pharmaceutical reactor with a strong focus on its volumetric capacity and heat transfer capabilities. The primary goal is to replicate design and control strategies at the laboratory or pilot scale to analyze and produce generic semisolid formulations. METHODS: Computational fluid dynamics and heat transfer modeling, utilizing the finite volume method, were employed to determine the reactor's performance and particle trajectory during the mixing and stirring. This allowed for the establishment of optimal operational parameters and variables. Furthermore, prototypes were constructed at 1:2.5 and 1:15 scales to examine the reactor's morphology, ensure volumetric versatility, and conduct mixing, homogenization, and coloration tests using varying volumes. RESULTS AND CONCLUSIONS: The outcomes of this study yielded a versatile reactor suitable for processing pharmaceutical semisolids at both laboratory and pilot-scale volumes. Notably, the reactor demonstrated exceptional volumetric capacity within a single vessel while effectively facilitating heat transfer to its interior.

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The usage of flow-diverting stents in the treatment of intracranial aneurysms is widespread due to their high success and low complication rates. However, their use is still not officially recommended for bifurcation aneurysms, as there is a risk of generating ischemic complications due to the reduced blood flow to the jailed branch. Many works utilize computational fluid dynamics (CFD) to study how hemodynamic variables respond to flow diverter placement, but few seem to use it to verify flow variation between branches of bifurcation aneurysms and to aid in the choice of the best ramification for device placement. This investigation was performed in the present work, by comparing wall shear stress (WSS) and flowrates for a patient-specific scenario of a middle cerebral artery (MCA) aneurysm, considering device placement on each branch. A secondary objective was to follow a methodology that provides fast results, envisioning application to daily medical practice. The device was simplified as a homogeneous porous medium, and extreme porosity values were simulated for comparison. Results suggest that stent placement on either branch is both safe and effective, significantly reducing WSS and flow into the aneurysm while maintaining flow to the different ramifications within acceptable thresholds.

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The present work aimed to study, predict and understand benzene migration that occurred during an industrial spill using numerical simulation by computational fluid dynamics. Advection, diffusion and adsorption were the main mechanisms considered that governed the spill incident. The incident occurred due to a fracture under a fuel oil storage tank. The tank was located on a hill 18 m high, and the initial value of benzene concentration (soil saturation) was 60 ppm. When the spill was discovered, samples in the affected zone were taken using an experimental design. Many samples showed a greater concentration of benzene than allowed by Mexican Official Standards (MOSs) (15 ppm). The concentrations found 100 m away from the spill were around 60 to 15 ppm. Due to the spill being under the tank, it was difficult to discover. The numerical simulation provided an estimate that the spill started around 2 years ago. The type of soil in the afflicted zone is rocky, and, consequently, it is difficult to estimate how long it will take to reach the concentration allowed by the MOSs, but the numerical simulation predicts that this concentration will be reached in 14 years. Experimental values of the spill contaminant concentration were statistically similar to the CFD estimated data (p < 0.05).

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The CCN51 cocoa bean variety is known for being highly resistant to diseases and temperature variation and for having a relatively low cultivation risk for the producers. In this work, a computational and experimental study is performed to analyze the mass and heat transfer within the bean when dried by forced convection. A proximal composition analysis is conducted on the bean testa and cotyledon, and the distinct thermophysical properties are determined as a function of temperature for an interval between 40 and 70 °C. A multidomain CFD simulation, coupling a conjugate heat transfer with a semiconjugate mass transfer model, is proposed and compared to the experimental results based on the bean temperature and moisture transport. The numerical simulation predicts the drying behavior well and yields average relative errors of 3.5 and 5.2% for the bean core temperature and the moisture content versus the drying time, respectively. The moisture diffusion is found to be the dominant mechanism in the drying process. Moreover, a diffusion approximation model and given kinetic constants present a good prediction of the bean's drying behavior for constant temperature drying conditions between 40 and 70 °C.

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This work aims to select a photoreactor flow configuration and operational conditions that maximize the Photocatalytic Space-time Yield in a photoelectrocatalytic reactor to degrade Reactive Red 239 textile dye. A numerical study by Computational Fluid Dynamics (CFD) was carried out to model the phenomena of momentum and species transport and surface reaction kinetics. The photoreactor flow configuration was selected between axial (AF) and tangential (TF) inlet and outlet flow, and it was found that the TF configuration generated a higher Space-time Yield (STY) than the AF geometry in both laminar and turbulent regimes due to the formation of a helical movement of the fluid, which generates velocity in the circumferential and axial directions. In contrast, the AF geometry generates a purely axial flow. In addition, to maximize the Photocatalytic Space-time Yield (PSTY), it is necessary to use solar radiation as an external radiation source when the flow is turbulent. In conclusion, the PSTY can be maximized up to a value of 45 g/day-kW at an inlet velocity of 0.2 m/s (inlet Reynolds of 2830), solar radiation for external illumination, and internal illumination by UV-LEDs of 14 W/m2, using a photoreactor based on tangent inlet and outlet flow.

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In the present work, a vertical axis turbine with straight blades was analyzed through a numerical simulation in three dimensions, the performance of the turbine was studied while synthetic jets were used as an active flow control method. To carry out the simulations, the Unsteady Reynolds Averaged Navier-Stokes (URANS) equations were solved on Star CCM+, through the k-ω SST turbulence model. The dynamics of the turbine movement were described using the Overset Mesh technique, capturing the transient characteristics of the flow field. Hydrodynamic coefficients and vorticity fields were obtained to describe the flow behaviour, and the results were compared with two-dimensional simulations of the same system. Turbine performance with tangential synthetic jets located on the intrados and extrados of the airfoil shows an increase in the torque and power output of the turbine. Moreover, using simple estimates, synthetic jets used less power than the increment in power generated at the turbine shaft, showing that efficiency of the turbine increases with the use of synthetic jets. However, the increment in the turbine performance is not as high as in previous two-dimensional studies reported in the literature.

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Photoelectrocatalysis has been highlighted as a tertiary wastewater treatment in the textile industry due to its high dye mineralisation capacity. However, design improvements are necessary to overcome photo-reactors limitations. The present work proposes a preliminary configuration of a photoelectrocatalytic reactor to degrade Reactive Red 239 (RR239) textile dye, using computational fluid dynamics (CFD) to analyse the mass transfer rate, radiation intensity loss (RIL), and its effect on kinetics degradation, over a photoelectrode based on a TiO2 nanotube. A study to increase the space-time yield (STY) was carried out through mass transfer rate and kinetic analysis, varying the optical thickness (δ) between the radiation entrance and the photocatalytic surface, photoelectrode geometry, inlet flow rate, and the surface radiation intensity. The RIL was determined using a 1D Beer-Lambert-based model, and an extinction coefficient experimentally determined by UV-Vis spectroscopy. The results show that in RR239 solutions below concentrations of 6 mg/L, a woven mesh photoelectrode and an optimal optical thickness δ of 1 cm is enough to keep the RIL below 15% and maximise the mass transfer and the STY in around 110 g/m3-day.

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Due to the increase in the number of people affected by chronic renal failure, the demand for hemodialysis treatment has increased considerably over the years. In this sense, theoretical and experimental studies to improve the equipment (hemodialyzer) are extremely important, due to their potential impact on the patient's life quality undergoing treatment. To contribute to this research line, this work aims to study the fluid behavior inside a hollow fiber dialyzer using computational fluid dynamics. In that new approach, the blood is considered as multiphase fluid and the membrane as an extra flow resistance in the porous region (momentum sink). The numerical study of the hemodialysis process was based on the development of a mathematical model that allowed analyzing the performance of the system using Ansys® Fluent software. The predicted results were compared with results reported in the literature and a good concordance was obtained. The simulation results showed that the proposed model can predict the fluid behavior inside the hollow fiber membrane adequately. In addition, it was found that the clearance decreases with increasing radial viscous resistance, with greater permeations in the vicinity of the lumen inlet region, as well as the emergence of the retrofiltration phenomenon, characteristic of this type of process. Herein, velocity, pressure, and volumetric fraction fields are presented and analyzed.

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Capsule-based, single-dose dry powder inhalers (DPIs) are commonly-used devices to deliver medications to the lungs. This work evaluates the effect of the drug/excipient adhesive bonding and the DPI resistances on the aerosol performance using a combination of empirical multi-stage impactor data and a fully-coupled computational fluid dynamics (CFD) and discrete element method (DEM) model. Model-predicted quantities show that the primary modes of powder dispersion are a function of the device resistance. Lowering the device resistance increases its capacity to transport a wider range of particle size classes toward the outlet and generate more intense turbulence upstream therein. On the other hand, a higher device resistance increases the velocity of the tangential airflow along the device walls, which in turn increases the intensity of particle/device impaction. Correlating model data and experimental results shows that these differing powder dispersion mechanisms affect different formulations differently, with finer aerosols tending to result when pairing a lower resistance device with formulations that exhibit low API/excipient adhesion, or when pairing a high resistance device with more cohesive formulations.

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The aim of this paper was to analyze, using computational fluid dynamics (CFD), a heating system in a commercial broiler house. Data were collected in a broiler house located in the western mesoregion of Minas Gerais, Brazil. The data were collected at 10 a.m. on the seventh day of chicks' life in 16 points inside the house. A tetrahedral mesh was adopted for the simulation, and testing of the mesh yielded a geometry of 485,691 nodes. The proposed model was developed in a permanent state condition to simulate the temperature air inside the broiler house, and all other input variables were considered constant. The applied CFD technique resulted in satisfactory fitting of the air temperature variable along the broiler facility as a function of the input data. The results indicated that the model predicted the environmental conditions inside the broiler house very accurately. The mean error of the CFD model was 1.49%, indicating that the model is effective and therefore that it can be used in other applications. The results showed that the heating system provided favorable thermoneutral conditions for chicks in the biggest part of the broiler house. However, there were some areas with air temperature above and below the thermoneutral zone.