With the advances in computers and the growth of science in modeling physical phenomena, wildfire simulation software has become an instrumental tool for governments, agencies, and researchers to tackle the growing challenge of wildfires. Various models have been developed using different methodologies, and different software platforms were created using these models. The Rothermel model is one of the most widely accepted and utilized models in simulation software among agencies. This study discusses the differences in numerical results from three widely used software programs that utilize the Rothermel fire propagation model as their foundation. First, each software will be introduced and explained, and their differences will be discussed. In the next step, multiple cases will be defined and simulated with identical inputs using each software. The effects of different slope and wind conditions on the results will be analyzed by designing four simple scenarios. Although it is acknowledged that numerous factors influence wildfire behavior, the analysis demonstrated that just these two factors were sufficient to reveal significant discrepancies among the software. The results of the simulations will be analyzed, and the software will be compared through a discussion. The results show that by increasing the complexity of the scenarios, the difference in results from each software increases. The differences in results between platforms with identical scenarios emphasize that researchers and decisionmakers must recognize these variations and exercise extra caution when utilizing wildfire simulation tools for decision-making and operational management.

This paper presents the experimental acoustic assessment and optimization of a novel solid visor with aerodynamic sealing for medical care. This Personal Protective Equipment (PPE) ensures an effective aerodynamic sealing of the breathing zone thus reducing the risk of inhaling droplets and aerosols carrying a potential infectious agent. The PPE relies on an air curtain system that may generate considerable noise unsuitable for prolonged usage, so it is essential to investigate solutions to reduce the noise level. The main investigated sound descriptors were the A-weighted Noise Equivalent Level, the Third-Octave Frequency Distribution, and the Speech Intelligibility Index (SII), considering different solutions for air flow rate, tube diameter, thickness and insulation, configurations of the tube splitter and plenum, and the incorporation of physical barriers and a sound muffler. Through several optimizations, noise equivalent levels were reduced by 20 to 30 dBA for air flow rates of 15 to 30 l/min. The final prototype generates a maximum noise level of 45.2 dBA. The SII was improved from poor to excellent, with values close to 1 for all air flow rates considered. The impact on the speech was investigated and the results were also compared to those obtained with a surgical mask and a FFP2 respirator. This study shows the potential of employing different strategies to enhance the acoustic performance of personalized air-curtain protective devices.

This paper presents a numerical model for simulating melting and solidification driven by natural convection, and validates it against a previous experiment. The experiment involved filling a rectangular aluminum enclosure with RT28HC Phase Change Material (PCM) to 95% of its capacity. To investigate the thermal behavior of the PCM during phase change, the enclosure underwent independent heating and cooling procedures. The simulation was conducted using ANSYS CFX®, and the additional heat source (AHS) method was implemented in conjunction with the Boussinesq approximation to account for the latent heat during melting and solidification driven by natural convection. This allowed the calculation of temperature fields, the melted fraction, and fluid dynamics during phase change. The momentum equations were modified to include a source term that accounted for a gradual decrease in fluid velocity as the PCM transitions from solid to liquid. To account for density variation, an artificial specific heat curve was implemented based on the assumption that the product of density and specific heat remains constant during phase change. The proposed numerical model achieved good agreement with the experimental data, with an average root mean square error of 2.6% and 3.7% for temperature profiles during charging and discharging simulations, respectively. This model can be easily implemented in ANSYS CFX® and accurately predicts charging and discharging kinetics, as well as stored/released energy, without any numerical convergence issues.

This paper presents the performance assessment of a novel air-sealed visor for medical care based on experi-ments. This Personal Protective Equipment (PPE) provides effective aerodynamic sealing of the breathing zone, thus reducing the risk of inhaling droplets and aerosols carrying a potential viral load. The air curtain supply system was designed after computational fluid dynamics exploratory simulations to determine suitable airflow conditions. The main parameters under study are the air curtain velocities and the fraction of contaminated air in the breathing zone. The impact of different airflow rates, human breathing, thermal plume and lateral barriers to reduce the risk of leakage, was investigated. For the designed airflow rate and considering the worst-case sce-nario with a contaminated environment, results indicate that this PPE can reduce the contaminated air in the breathing zone by 31% and 82%, without and with lateral physical barriers, respectively. Although the human body thermal plume has a high impact on the air curtain velocity profile, it just affects the device efficiency by 2%. The breathing process increases the air curtain velocities improving the PPE efficiency by 32%. This study shows the potential of using a visor with aerodynamic sealing as an infection control barrier for healthcare workers.

This work proposes a new configuration of liquid piston compressors and a methodology for their optimization, with special attention to heat removal from the compressing gas, in order to minimize the mechanical work required for the compression process. The adopted approach starts with the solution of the governing equations through a 0D model (lumped approach). A new correlation for the heat transfer coefficient is presented to calculate the sensible heat transfer from the compressing gas to the cooling liquid. The results of the 0D model are validated by comparison with experimental and numerical data from the literature and with performed CFD calculations. In the proposed geometric configuration, heat is removed from the compressing gas through a tubes bundle inserted in the compression chamber, the liquid cooling medium flowing inside the tubes. This geometric configuration was chosen because it is simple to design and common materials and manufacturing processes can be used for its manufacturing. In addition, no regeneration of the inserts is required from cycle to cycle, making that configuration ideal for cyclic operation. The parametric study performed focuses on the dependence of the overall efficiency on the number and diameter of the cooling tubes and the speed of the liquid piston. It is found that the overall efficiency is highest for a given number of tubes with at a specific diameter, and that the combination of a few cooling tubes with a larger diameter and a higher piston speed gives the best overall efficiency.

Narrow Neck Press and Blow is a glass moulding process that produces a lightweight container by pressing the glass in the blank mould, baffle, and neck ring to form a parison. This paper presents a cyclic transient computational fluid dynamics study to evaluate the thermal performance of a novel blank mould (ShellMould) for the glass industry. ShellMould consists of two cast iron parts, an outer shell and a moulding core, and a conformal cooling channel between these parts. Fins placed strategically inside the conformal channel promote heat transfer between the cooling airflow and the blank. A mould with straight cooling channels currently used by the glass industry was considered as the reference case model. The mould thermal performance was assessed based on three parameters: an Index of Temperature Heterogeneity, the heat removal rate, and the average temperature in the moulding surface at the blank, baffle seal, and neck ring. It is shown that ShellMould can reduce the operating temperature by 100 °C and improve the heat removal rate by 190 up to 202 [W]. Results reveal the main challenges for improving the ShellMould cooling and temperature homogeneity, mainly in the neck ring, where the cooling efficiency dropped by 10%.

In the present study, a numerical model was developed to predict the flow pattern inside a broiler building. The model was intended to predict the velocity fields inside the domain and the ammonia (NH3) emitted or released by litter from poultry housing. The numerical model was developed in computational fluid dynamics (CFDs) commercial code and intended to represent a commercial broiler building and to simulate the 3D and heat transfer in steady-state flow. The evaporative cooling pads were also included in the model. The validation of the model was based on experimental measurements obtained in previous studies. The simulations were focused on the summer, winter, and mid-season conditions. Numerical measurements of NH3 concentration were compared with the experimental measurements, and a quite good agreement was verified. The numerical results allowed the characterization of: the inside flow pattern developed for the summer and winter periods and the NH3 and velocity field distributions inside the broiler building. It was found that NH3 concentration increased along the tunnel, as a result, especially, of the low flow rate of the exhaust fan. It was verified that the low velocities inside domain were not sufficient to remove the gaseous pollutants.

Wind turbine wakes have a strong impact on wind farms as they affect the power output and the turbulence level. These factors have a determinant impact on turbines lifetime. Thus, wake modelling is of critical importance to the wind energy industry, playing a central role in the optimization of wind farm layouts. This work aims at assessing some of the available analytical wake models that modify the computed wind field by CFD as a postprocessing correction tool. Such validation was done with recourse to experimental SCADA data obtained in an onshore wind farm with eight wind turbines distributed by two rows. Conclusions were drawn for the Jensen, Jensen2D, Larsen, Gaussian BPA and Gaussian Ishihara models, by analyzing the computed velocity ratio relative to the upstream leading turbine, both in a single wake and in multiple wake situations.

The fast spreading of the SARS-CoV-2 virus led to a significant increase in the demand for personal protective equipment (PPE). Healthcare professionals, mainly dentists, work near the patients, increasing their risk of infection. This paper investigates the effectiveness of an air-curtain sealing effect in a newly designed visor developed to reduce the risk of contracting a respiratory infection. This PPE was developed by computational fluid dynamics (CFD) modeling. CFD results show that the aerodynamic sealing in this PPE device effectively protects the user's face by 43% from a contaminated environment. The experiments considered two different tests: one using a tracer gas (CO2 ) to simulate a gaseous contaminant inside and outside the PPE face shield and a second test using smoke to simulate aerosol transport and evaluate the PPE efficiency. The particle concentration within the aerodynamically sealed PPE was evaluated and compared with the protection efficiency of other PPE. Results show similar protection levels for particles in the 1-5 μm range between the prototype and a KN95 respirator. The combined use of this novel PPE with aerodynamic sealing and a physical mask (KN95 or surgical) produced protection efficiency values within the range of 57%-70% for particles greater than 0.5 μm. This study reveals the potential of using an air curtain combined with a face shield to reduce the risks from contaminated environments.

In the present work, simulations of the flow around the NACA 0018 airfoil operating at Reynolds number 7 × 105 are performed using the EasyCFD software package. The influence of the advection scheme and turbulence model on the computed lift, drag and momentum coefficients is presented and an evaluation of the obtained results is made by comparison with published experimental data. It is concluded that predictions agree very well with experimental data up to 18° angle of attack, when using the SST turbulence model with the second order advection scheme. Limitations of simulations are shown when the airfoil operates at larger angles of attack, where unsteady periodic flow is verified. The turbulence model and the advection scheme affects both lift and drag values, but to a larger extent for drag. Predictions at high angles of attack overestimate both lift and drag coefficients, but underestimate the momentum coefficient.

This paper assesses the thermal performance of four microencapsulated-PCM-based samples that can be used in the design of new thermal energy storage systems for buildings: a PCM-enhanced plasterboard; three different fin-enhanced aluminium containers filled with the PCM. The methodology covers: the thermophysical characterization of the PCM-based products; the development of charging and discharging experiments to provide data for numerical validation purposes; the numerical modelling considering five different methods dispersed in literature, and a new-improved method. The main goals are to validate the numerical predictions against reliable experimental results and to find out which method is preferable for future simulations. The 3D numerical simulations were based on the effective heat capacity (EHC), additional heat source (AHS) and enthalpy (H-P) approaches. The first two methods were implemented in ANSYS CFX®; the other in ANSYS FLUENT®. For the EHC method, four different ways to specify the variation of the effective specific heat with temperature were assessed. While the H-P commercial code already implemented in ANSYS FLUENT® was used, the other two methods implemented in ANSYS CFX® were developed and validated for the purpose of this study.Good agreement between numerical and experimental results was achieved for all numerical approaches. In fact, it was concluded that the six numerical methods can be used to simulate heat diffusion with solid-liquid phase-changes. However, it was verified that the EHC method with the triangular or the self-adjusted triangular profiles is preferable for both charging and discharging simulations, since it can be drawn based on few information about the PCM-based products; it ensures good predictions of both charging/discharging kinetics and stored/released energy; it can be used without compromising computation time in comparison to other methods. The EHC method with the rectangular profile, recurrently used in literature, exhibits some convergence issues whose resolution has required longer computation times.

Este artigo tem análise estruturada no materialismo dialético-histórico, dentro dos preceitos da Cultura e Sistemas Simbólicos. Investiga a prisão sob a ótica dos discursos de Paulo. Aborda o cárcere, discute a crença, infere na reflexão do apóstolo com relação aos marginalizados em meio à cultura e sistemas simbólicos que trespassam a religião e os costumes. Desde a Antiguidade as autoridades trabalham essa expressão social paradigmática permeada pela fé, desespero e realidade. Na contemporaneidade as políticas públicas manipulam esta expressão da questão social, retrato da sociedade capitalista, consumista, movida no fluxo incessante, a destinar mínimos sociais à classe trabalhadora. A luta pelo direito de viver estreita relações materiais-filosóficas, humano-racionais-legais as quais alicerçam a consciência do trabalhador. O sujeito social resiste à alienação pelo capital atravessado por uma existência atada à trama econômica, política e cultural que dá sopro à sobrevivência. Ao caminhar por este paradigma a escrita busca dialogar sobre A Interface Evangelho e Prisão na Contemporaneidade. O foco é em conceitos e discursos postos sobre a fé, a penalização e a pós moderna idade.

A numerical study is conducted concerning the improvement of radial plane fins heat sinks for natural convection cooling of light-emitting diode (LED) lamps. The main objective is to maintain the temperature of the heat sink base below a prescribed threshold for a given released heat flux at the heat sink, minimizing its mass and maintaining at a reasonably simple level the manufacturing processes and operations required for its production. Starting from a previously optimized heat sink for the same purpose, constituted by complete rectangular radial plane fins, the present study aims at further improvements by considering incomplete rectangular radial plane fins. The main objective of this study is to find the best profile for the turning operation to obtain the radial plane fins lighter configuration. It is found that this can be achieved by removing part of the upper internal corners of the rectangular fins, more specifically shaping a curved cut, leading to heat sink mass reduction up to 32.4%. The geometry of the improved heat sink is of cylindrical nature, obtained from cutting an aluminum extruded bar comprising a cylindrical central core and a number of uniformly distributed rectangular radial plane fins, followed by a simple turning operation to remove their upper internal corners. Even if results concern a particular LED lamp, the main ideas and approach prevail to improve other types of heat sinks for general light and/or electronic components cooling.

Group work is a methodology that allows the student to learn in interaction with his/her peers, through active involvement and participation in the teaching-learning process. However, this teaching practice isn't always welcome by all teachers, as it implies a pedagogical organization that contrasts in many ways to the traditional teaching model. In addition, there is still no common understanding of the age at which it should be implemented or of the actual benefits it can provide to students. Bearing this assumption in mind, our goal was to find out more about teachers and students' perspectives on group work methodology and how it should be used in the different subject areas of primary education. Our main research objectives were to understand the importance attached to this methodology, the subjects in which this methodology is most frequently implemented, the subjects where students work better in group, and the kind of training in group work methodology received by teachers. A questionnaire was applied in three School Groupings located in Viseu (centre region of Portugal) to a sample composed of 42 primary teachers and to their 4th grade students (218 students). 4th grade was the school year selected because students had already developed group work assignments before. Consequently, they were able to reflect on that past practice. The data obtained showed that group work is felt to be particularly important, both to teachers and students. Differences are quite significant when it comes to express how often that methodology is implemented in the classroom, though. Environmental Studies, Physical Education, and Dramatic Expression are the subject areas where teachers claim to use this methodology on a more regular basis. It should also be noted that more than half of the teachers admit they had no training whatsoever in the field of group work. The conclusions of this study indicate that a more frequent use of this methodology in primary education is beneficial, and highlight the clear need to invest in teacher training, namely in a training plan that focuses on the organization and development of group work in the classroom as a means to improve pedagogical action.

Energy for life is produced inside the internal human energy factory, the mitochondrion, where low oxygen levels are likely to be correlated with stressful behaviors. These include thriving for performance, competition and perfection. One way to build a sustainable society is to reduce the daily stress, allowing human energy to target the control of energy resources and environmental safeguarding. So, it is important to assess the impact of decreased oxygen (hypoxia) in the body, especially in the brain, as a small imbalance in brain activity can affect vital energy production essential for sustainable life activities. This work addressed fluorescence changes associated with the formation of FAD and of reactive oxygen species (ROS), evoked by different levels of hypoxia. Exposing the slices to 0% and 21% O2, caused an increase in FAD autofluorescence. Upon reoxygenation (95% O2) the 0% O2 trace did not recover, while the 21% O2 signal decreased reaching the baseline. In contrast, at 40% and 65% O2 the FAD fluorescence decreased reversibly. Regarding ROS fluorescence, no significant changes were observed during the application of 0% and 21% O2. However, at 40% and 65% O2, the signals were enhanced recovering partially when the initial oxygen level (95% O2) was reintroduced.

In recent studies, computational fluid dynamics (CFD) simulations in OpenFOAM have been used to model the oscillation of a planar jet impinging onto a free surface and analyze methods to suppress the subsequent flow characteristics. This phenomenon occurs in several industrial processes, such as dipping, and is likely to affect the quality of products, with consequent rejection, resulting from the free surface wavering induced by the jet. Therefore, to prevent this, CFD was used to analyze alternatives, lowering the higher costs of manufacturing and on-site testing solutions. The predicted flapping frequency is benchmarked against experimental data and used to perform grid independency tests and select the most appropriate Reynolds-averaged Navier-Stokes (RANS) turbulence model. Finally, various deflector geometries, placed above the inlet jet, were tested to reduce the free surface oscillations.

The dry tray pressure drop (Delta P-d) is a design parameter that provides preliminary information about the total pressure drop. This work aimed to assess correlations for Delta P-d prediction for different types of trays without downcomer and to evaluate the effects of the free area ratio (phi) and the hole diameter (d) on Delta P-d. Assessment was performed by comparing results of several correlations with those from an experimentally validated computational fluid dynamics simulation. The study shows that the correlations of Cervenka and Kolar, Bennett, Agrawal and Cook, and Stichlmair and Mersmann predicted the dry pressure drop satisfactorily. The correlation of Bennett, Agrawal and Cook can be recommended for the prediction of Delta P-d for a wide range of geometries and operation conditions. Also, phi has a higher influence on Delta P-d than d.

This paper presents a parametric study on the performance of an air curtain installed over an access door of a refrigerated room. The aim of this work is to quantify, in an integrated way, the influence of the following geometrical and dynamic parameters: door height; temperature difference between rooms, nozzle thickness; initial orientation angle; jet discharge velocity. A numerical model was used to simulate the turbulent non-isothermal 3D airflow generated in the transient period after the door is opened, with the air curtain device turned on or off. Turbulence effects were taken into account with the k-ω SST model. Results show that the optimum discharge velocity of the air curtain increases with the door height, as well as with the temperature difference between both sides of the air curtain. It was also possible to find an optimum jet nozzle width corresponding to maximum sealing efficiency and lower jet airflow rate. A proposal is made for an empirical correlation to predict the optimum jet discharge velocity as function of the variables used in the parametric study. Additionally, to ensure that the air curtain operates near the optimum conditions, the appropriate air curtain settings are discussed and a new strategy is suggested.

This work evaluates the thermal behaviour of a small aluminium-containerbased thermal energy storage (TES) unit filled with a microencapsulated phase change material (PCM) – Micronal ® DS 5001 X. ANSYS CFX ® software is used for the 3D numerical simulations, which are based on the Effective Heat Capacity (EHC) method considering a purely diffusive transient model. In the formulation, a new artificial self adjusted triangular profile was considered to account for the variation of the effective specific heat with temperature. Due to the artificial nature of this procedure, the correct prediction of the phase-change kinetics was analysed. For that purpose, some previously obtained experimental data were used for validating the numerical results. The amount of stored and released energy during charging and discharging was also evaluated. The main results of this numerical study show a very good agreement with both the kinetics of the phase-change processes (average and maximum errors of 2.9 % and 11.6 %, respectively, during charging; average and maximum errors of 1.7 % and 5.0 %, respectively, during discharging) and the total amount of stored/released energy during a complete experimental charging/discharging cycle of the PCM. Moreover, it was concluded that the EHC method with a self-adjusted triangular profile to account for the variation of the effective specific heat with temperature is a good method for modelling heat diffusion problems with solid-liquid phase-change. N. Soares, N. Rosa, T. Matias, A.G. Lopes, P.N. Simões, L. Durães and J.J. Costa 2

The incident wind velocity in a forest fire is one of the main factors affecting fire spread. Although buoyancy due to the fire heat release modifies the wind field, the standard procedure for fire simulation takes the undisturbed wind field, computed in the absence of the fire thermal effects. The present work addresses this problem, by using a method to take into account the mutual interaction (two-way coupling) between fire and wind. This study is based on the FireStation system, a software package that combines a semi-empirical fire spread model with a Navier-Stokes solver for wind calculation, using a dynamic interchange between the fire spread model and the wind model. The present work describes the application of this model to a real wildfire case, the two-way coupling approach proving to be a better option, with predictions of fire size and shape in closer agreement with the observed ones.