CFD Investigation of an Innovative Additive Manufactured POCS Substrate as Electrical Heated Solution for After-Treatment Systems

In the last decade, additive manufacturing (AM) techniques have been progressively applied to the manufacturing of many mechanical components. Compared to traditional techniques, this technology is characterized by disruptive potential in terms of the complexity of the objects that can be produced. This opens new frontiers in terms of design flexibility, making it possible to create new components with optimized performances in terms of mechanical properties and weight. In this work, the focus is on a specific field of application: the development of novel porous media structures which can be the basis of advanced after-treatment systems for internal combustion engines. In particular, the possibility to design periodic open cellular structures (POCSs) that can be applied as catalytic substrates opens new perspectives in terms of flexibility and integrated functionalities. The present study investigates an innovative solution where the catalytic substrates are located in the pipes of the exhaust manifolds of a high-performance engine. A preliminary characterization of the pressure drop induced by the POCS structure is carried out, with a particular focus on the impact of the backpressure on the engine performances. Moreover, each POCS integrates an electrical circuit which is used to promote the heating of the device, with beneficial effects on the light-off of the catalytic reactions. An advanced CFD model is applied to evaluate the potential of the solution, comparing the pollutant conversion with that of the baseline configuration equipped with a standard after-treatment system solution

Efectos del camuflaje en la salud mental de las personas con el trastorno del espectro autista

El Trastorno del Espectro Autista (TEA) es un desorden del neurodesarrollo cuya prevalencia se encuentra en aumento. Asociado a este, se da un fenómeno denominado camuflaje, el cual se usa como una herramienta por personas autistas para enmascarar dificultades sociales en contextos neurotípicos generando efectos negativos sobre su salud mental. El objetivo de este trabajo es identificar los hallazgos recientes sobre los efectos del camuflaje en la salud mental de las personas TEA. Se realizó una búsqueda utilizando algunas pautas de la guía PRISMA (Urrútia & Bonfill, 2010). Las bases de datos consultadas fueron PubMed, Research gate, BioMed y Sage Journal tomándose en consideración investigaciones realizadas entre el 2015 y 2021. Se seleccionaron siete investigaciones que evaluaban el camuflaje y salud mental en personas autistas. Las evidencias indican que el camuflaje se da tanto en hombres como mujeres, sin embargo, se presenta un mayor uso por parte de las mujeres TEA. Esto fomenta diagnósticos tardíos para este grupo, lo que incide más efectos contra la salud mental.Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder whose prevalence is increasing. In addition, it is accompanied by a phenomenon known as camouflaging, which is used by autistic people as a tool to mask social challenges in neurotypical settings, thus generating negative effects on their mental health. The aim of this work is to identify recent findings about the effects of camouflaging on people with ASD. A database search was conducted according to some of the PRISMA Guidelines (Urrútia & Bonfill, 2010). The databases searched were PubMed, ResearchGate, BioMed and SAGE Journal, and only research conducted between 2015 and 2021 was considered. A total of 7 research papers that assessed camouflaging and mental health on autistic people were selected. The evidence suggests camouflaging occurs in both men and women; however, it is more prevalent on women with ASD. This results in late diagnoses for such population, which impacts negatively on their mental health

Numerical study of compressor fouling mechanism based on Eulerian-Eulerian approach

AbstractThe paper describes a fluid dynamic numerical model to study the fouling mechanism for turbomachines (such as large gas turbines and small turbochargers). For this purpose, the gas-particle behaviour over a compressor blade is modelled using an open source CFD tool, OpenFOAM®. Through this model, two-fluid implicit equations system, with Eulerian-Eulerian approach is considered. This approach uses RANS turbulent models and also takes into account the particle fluid interactions. Applying Johnson-Kendal-Robert (JKR) theory, the particle deposition over the blade surface is predicted. According to the simulation results, there are certain regions which are facing the huge amount of deposition. The surfaces of these regions are prone to form an almost thick layer of sticked particles and affect the boundary layers and blade aerodynamics significantly. In order to capture this effect, a model to predict the deformation of the boundary with respect to deposition rate is also introduced

evaluating the performance of a rotary vane expander for small scale organic rankine cycles using cfd tools

Abstract This work proposes a focus on the simulation of a rotative volumetric expander via a CFD code. A customized application of OpenFOAMOR has been developed to handle the particular motion of the calculation grid. In particular, a prescribed shape of the stator has been defined in order to adapt the motion of the vanes along the whole cycle. The model uses a mesh to mesh interpolation technique, switching from a calculation grid to the new one on the basis of dynamic mesh quality considerations. This particular approach allows to account for the presence of leakages occurring between the stator and vane tips and also occurring at the top and bottom of the vanes. The fluid considered is the refrigerant R245fa, whose particular properties have been determined resorting to the NIST database. Experimental data, measured at different conditions of mass flow and fluid temperature, are compared to calculation results. Moreover, the CFD analysis has allowed the estimation of the influence of the leakage mass flow occurring at the tip of the vanes on the overall machine performances

A New Integrated Approach for the Prediction of the Load Independent Power Losses of Gears: Development of a Mesh-Handling Algorithm to Reduce the CFD Simulation Time

To improve the efficiency of geared transmissions, prediction models are required. Literature provides only simplified models that often do not take into account the influence of many parameters on the power losses. Recently some works based on CFD simulations have been presented. The drawback of this technique is the time demand needed for the computation. In this work a less time-consuming numerical calculation method based on some specific mesh-handling techniques was extensively applied. With this approach the windage phenomena were simulated and compared with experimental data in terms of power loss. The comparison shows the capability of the numerical approach to capture the phenomena that can be observed experimentally. The powerful capabilities of this approach in terms of both prediction accuracy and computational effort efficiency make it a potential tool for an advanced design of gearboxes as well as a powerful tool for further comprehension of the physics behind the gearbox lubrication

A comprehensive methodology for computational fluid dynamics combustion modeling of industrial diesel engines

Combustion control and optimization is of great importance to meet future emission standards in diesel engines: increase in break mean effective pressure at high loads and extension of the operating range of advanced combustion modes seem to be the most promising solutions to reduce fuel consumption and pollutant emissions at the same time. Within this context, detailed computational fluid dynamics tools are required to predict the different involved phenomena such as fuel-air mixing, unsteady diffusion combustion and formation of noxious species. Detailed kinetics, consistent spray models and high quality grids are necessary to perform predictive simulations which can be used either for design or diagnostic purposes. In this work, the authors present a comprehensive approach which was developed using an open-source computational fluid dynamics code. To minimize the pre-processing time and preserve results' accuracy, algorithms for automatic mesh generation of spray-oriented grids were developed and successfully applied to different combustion chamber geometries. The Lagrangian approach was used to describe the spray evolution while the combustion process is modeled employing detailed chemistry and, eventually, considering turbulence-chemistry interaction. The proposed computational fluid dynamics methodology was first assessed considering inert and reacting experiments in a constant-volume vessel, where operating conditions typical of heavy-duty diesel engines were reproduced. Afterward, engine simulations were performed considering two different load points and two piston bowl geometries, respectively. Experimental validation was carried out by comparing computed and experimental data of in-cylinder pressure, heat release rate and pollutant emissions (NOx, CO and soot)

Echocardiographic indices in normal German shepherd dogs

Sixty clinically normal German shepherd dogs, 31 males and 29 females, ranging in age from 1 and 5 years and with a body weight ranging from 22 to 37.2 kg, were examined by the two-dimensional mode, M-mode, and Doppler echocardiography. In Doppler mode, the mitral valve flows were obtained, where the aim was to determine the velocity peaks and ratios of the E and A waves and the mitral E wave deceleration time. The velocity peaks were obtained for the tricuspid, pulmonary and aortic valves. On the left ventricular outflow tract flow, the time velocity integral and aortic cross-sectional area was used to calculate the cardiac output. A statistically significant correlation with the body weight was found for the systolic left atrial and diastolic aortic diameter on two-dimensional mode. On M-mode, there was a significant correlation between the body weight and the systolic left atrium and diastolic aortic dimension, systolic and diastolic left ventricular, septal and posterior wall dimensions. Doppler echocardiography showed that there was no significant correlation between the body weight and the mitral, tricuspid, pulmonary and aortic valves flows. These results demonstrate that it is important to know the normal echocardiographic values for German shepherd dogs because there are some characteristics peculiar to this particular breed. The data obtained is expected to be helpful for studies on small animal cardiology