NUMERICAL INVESTIGATION OF HEAT TRANSFER IN A TURBULENT FLOW IN CHANNELS WITH GAP

Turbulent flow in channels with gap is still a challenge for engineering. The velocity fluctuations and the appearance of coherent structures have been playing a major role in forced convective heat transfer process between the warm tube walls and the cooling fluid. In this paper numerical simulation of non-isothermal turbulent flow in a rectangular channel containing only one tube was performed. Unsteady Reynolds Navier-Stokes along with the energy equation were applied to model the problem. In order to overcome the closure problem the turbulence was modeled applying SAS model. The simulated geometry consists of a heated cylindrical tube, placed 10 mm from the bottom wall of the rectangular duct. The fluid flows externally to the heated tube along the mainstream direction. The channel’s length was based on the tube diameter, yielding L/D equal 80

Avaliação do risco cirúrgico nos doentes com cancro colo-rectal: POSSUM ou ACPGBI?

Introduction: Several models have been developed with the purpose of predicting surgical risk of patients submitted to colorectal cancer surgery. However, to date, there isn’t any model that fulfills this purpose in a satisfactory manner. Methods: We consulted the clinical processes of 345 patients, who were submitted to surgical colorectal cancer treatment at the General Surgery department in Hospital de Braga, and calculated surgical risk based on the following risk assessment scales: Physiological and Operative Seve- rity Score for the enumeration of Mortality and Morbidity (POSSUM), Portsmouth POSSUM (P-POSSUM), ColoRectal POSSUM (CR-POSSUM), Association of Coloproctology of Great Britain and Ireland (ACPGBI) and modified ACPGBI. For all scales, we com- pared observed and previewed mortality and calculated Receiver Operating Characteristic (ROC) curve. Results and conclusion: he study included 345 patients submitted to colorectal cancer surgery of which 211 were male and 126 were female, with an average age of 68 years old. Most patients (61,0%) presented with colon cancer and 86,4% were submitted to elective surgery. Post-operatory mortality at 30 days was 3,768%. In the present study, despite no model being statistically better than the other, the ACPGBI model was the one that showed more discriminative properties which, along with easier applicability, makes it the best model for evaluating surgical risk in our population.Keywords: colorectal cancer, POSSUM, P-POSSUM, CR-POSSUM, ACPGBI Introdução: Diversos modelos têm sido desenvolvidos para prever o risco cirúrgico dos doentes submetidos a cirurgia por cancro colo- -rectal (CCR), contudo actualmente ainda não existe nenhum que responda satisfatoriamente a essa necessidade. Material e métodos: Foram analisados os processos de 345 doentes submetidos a tratamento cirúrgico por CCR no Serviço de Cirurgia Geral do Hospital de Braga e calculado o risco cirúrgico previsto pelas escalas Physiological and Operative Severity Score for the enumeration of Mortality and Morbidity (POSSUM), Portsmouth POSSUM (P-POSSUM), ColoRectal POSSUM (CR-POSSUM), Association of Coloproctology of Great Britain and Ireland (ACPGBI) e ACPGBI modificado. Para todas as escalas de risco foi comparada a mortalidade prevista com a observada e realizada a análise de curva Receiver Operating Characteristic (ROC). Resultados e conclusão: O estudo incluiu 345 doentes operados por CRC, 211 homens e 126 mulheres com média de idade de 68 anos. Na maioria dos doentes (61,0%) o cancro localizou-se no cólon tendo sido a maioria (86,4%) submetidos a cirurgia de forma electiva. A mortalidade pós-operatória global observada aos 30 dias foi de 3,768%. No nosso estudo, apesar de nenhum dos modelos mostrar ser estatisticamente superior a outro, o modelo ACPGBI foi o que apresentou melhor capacidade discriminativa, o que aliado à maior facilidade de aplicação o torna no modelo escolhido para avaliar o risco cirúrgico, na nossa população. Palavras-chave (MeSH): cancro colo-rectal, POSSUM, P-POSSUM, CR-POSSUM, ACPGBI

Optimal mode decomposition for unsteady flows

A new method, herein referred to as optimal mode decomposition (OMD), of finding a linear model to describe the evolution of a fluid flow is presented. The method estimates the linear dynamics of a high-dimensional system which is first projected onto a subspace of a user-defined fixed rank. An iterative procedure is used to find the optimal combination of linear model and subspace that minimizes the system residual error. The OMD method is shown to be a generalization of dynamic mode decomposition (DMD), in which the subspace is not optimized but rather fixed to be the proper orthogonal decomposition (POD) modes. Furthermore, OMD is shown to provide an approximation to the Koopman modes and eigenvalues of the underlying system. A comparison between OMD and DMD is made using both a synthetic waveform and an experimental data set. The OMD technique is shown to have lower residual errors than DMD and is shown on a synthetic waveform to provide more accurate estimates of the system eigenvalues. This new method can be used with experimental and numerical data to calculate the ‘optimal' low-order model with a user-defined rank that best captures the system dynamics of unsteady and turbulent flow

Processes controlling atmospheric dispersion through city centres

We develop a process-based model for the dispersion of a passive scalar in the turbulent flow around the buildings of a city centre. The street network model is based on dividing the airspace of the streets and intersections into boxes, within which the turbulence renders the air well mixed. Mean flow advection through the network of street and intersection boxes then mediates further lateral dispersion. At the same time turbulent mixing in the vertical detrains scalar from the streets and intersections into the turbulent boundary layer above the buildings. When the geometry is regular, the street network model has an analytical solution that describes the variation in concentration in a near-field downwind of a single source, where the majority of scalar lies below roof level. The power of the analytical solution is that it demonstrates how the concentration is determined by only three parameters. The plume direction parameter describes the branching of scalar at the street intersections and hence determines the direction of the plume centreline, which may be very different from the above-roof wind direction. The transmission parameter determines the distance travelled before the majority of scalar is detrained into the atmospheric boundary layer above roof level and conventional atmospheric turbulence takes over as the dominant mixing process. Finally, a normalised source strength multiplies this pattern of concentration. This analytical solution converges to a Gaussian plume after a large number of intersections have been traversed, providing theoretical justification for previous studies that have developed empirical fits to Gaussian plume models. The analytical solution is shown to compare well with very high-resolution simulations and with wind tunnel experiments, although re-entrainment of scalar previously detrained into the boundary layer above roofs, which is not accounted for in the analytical solution, is shown to become an important process further downwind from the source

Occurrence and quantification of drosophila suzukii in the urban area of Vacaria, RS.

Drosophila suzukii, also called spotted-wing drosophila (SWD), is a fruit fly which originated in South-eastern Asia. This fly damages small fruits and usually disperses via passive transport in host fruits. Thus, tracking its occurrence is important in that it allows control strategies to be directed to urban areas as well. The purpose of this study was to evaluate the occurrence of D. suzukii adults inside and nearby 14 commercial establishments that sell fruits in the urban area of Vacaria, RS, at 2014 and 2016. SWD adults were captured by means of PET bottle traps baited with pure apple vinegar. A total Occurrence and quantification of Drosophila suzukii in the urban area of Vacaria, RS Regis S.S dos Santos et al. 589 Rev. Elet. Cient. UERGS, v. 3, n. 3, p. 588-599, 2017 of 23 flies (15 females and 8 males) and 51 flies (29 females and 22 males) were sampled in 2014 and 2016 respectively. On both occasions, the spotted-wing drosophila was detected in 64.3% of the establishments. In 2016 specifically, 13 females were collected at a sampling point inside a supermarket. The results show that control strategies should take into account the presence of the spotted-wing drosophila in urban areas, especially inside commercial stablishments, since this pest may be causing damage to fruits via crosscontamination. Keywords: Distribution. Fruit Trade. Infestation. Control Strategies. Cross-Contamination. Drosophila suzukii ou SWD é uma mosca das frutas nativa do sudeste da Ásia que danifica pequenos frutos, cuja dispersão é atribuída ao transporte passivo em frutas hospedeiras. O conhecimento sobre a ocorrência de SWD em ambientes urbanos é importante, pois permite que estratégias de controle também sejam direcionadas para as áreas urbanas. Neste contexto, foi avaliada a ocorrência de adultos SWD no entorno e interior de 14 mercados de frutas na área urbana do município de Vacaria, RS, nos anos de 2014 e 2016. Adultos de SWD foram monitorados com armadilhas feitas a partir de garrafas PET com vinagre de maçã puro como atrativo. Um total de 23 (15 fêmeas e 8 machos) e 51 (29 fêmeas e 22 machos) indivíduos foram amostrados em 2014 e 2016, respectivamente. Em ambos os anos, em 64,3 % dos pontos avaliados houve ocorrência de SWD. Em 2016, num ponto amostral foram coletadas 13 fêmeas no interior do mercado. Os resultados mostram que estratégias de controle para SWD devem levar em conta a sua ocorrência em áreas urbanas, especialmente no interior dos mercados, pois a praga pode estar causando danos nas frutas por infestação cruzada. Palavras-chave: Distribuição. Comércio De Frutas. Infestação. Estratégia De Controle. Infestação Cruzada