Wind tunnel experiments with neutral and convective boundary layer stabilities

The present contribution reports on the status of the STROMA experiment. As a novelty a new experimental setup in a wind tunnel allows to simulate different stability regimes with vertical heat flux in either direction. This is accomplished upon inserting a metal sheet equipped with Peltier elements into the floor of the experimental section II of the Prof. Joaquim Blessmann wind tunnel at LAC-UFRGS (Porto Alegre, Rio Grande do Sul state, Brazil). We show results and compare findings for two velocity magnitudes (1 Hz and 4 Hz) and with neutral and convective stability regime. Effects in the turbulent velocity field are presented with its dependence on height

Employing wind tunnel data to evaluate a turbulent spectral model

In this study, spectra obtained from wind tunnel data are compared with a model that describes observed atmospheric neutral spectra. The investigation points out that there is a good conformity between both spectra for the whole turbulent frequency domain. This result is significative since that the spectral model was obtained using only turbulent quantities measured in the planetary boundary layer. This similitude occurring with wind tunnel and atmospheric data furnishes a way to obtain connections between wind tunnel and atmospheric turbulent observations. The results, presented in this analysis, confirm the hypothesis that turbulence parameters observed in wind tunnel, can simulate real wind data measured in atmosphere

Perfis verticais dos espectros das velocidades turbulentas em uma torre micrometeorológica de 140 m

Multiresolution spectra of both horizontal and vertical wind components observed at a 140-m micrometeorological tower are analysed. The tower is located at the township of Linhares, ES, Brazil, at 4 km from the coast and nest to a thermal power plant. At nighttime, the spectral maximum is located at the largest temporal scales analyzed, being therefore related to nonturbulent low-frequency processes. During the day, spectral maxima of the horizontal wind components show little variation above 20 m.For the vertical component, on the other hand, the temporal scale of such maxima increases steadily with height.Espectros de multirresolução das componentes horizontais e verticais do vento observados em uma torre micrometeorológica de 140 m, localizada na cidade de Linhares, ES, a 4 km da costa e ao lado de uma usina termoelétrica, são analisados. No período noturno, o máximo de energia está localizado nas maiores escalas temporais analisadas, estando associado a processos não turbulentos de baixa frequência. Durante o dia, as escalas temporais associadas aos máximos espectrais das componentes horizontais do vento variam pouco com a altura acima de 20 m. Para a componente vertical a escala destes máximos é diretamente relacionada com a altura da observação

The Pampa-2016 experiment

ABSTRACTThe Pampa‐2016 experimental campaign was performed in a typical Pampa lowland South American region. It consisted of both surface flux measurements (at 3 and 29 m) and a radiosonde launched every 3 h. The resulting meteorological observations allowed for the analysis of turbulent properties associated with both a stable and a convective boundary layer. The combined analysis of the surface data and vertical soundings has revealed some general characteristics of the atmospheric boundary layer for both the nocturnal stable conditions and the daytime convective environment. The continuous surface measurements showed that the nocturnal stable inversion, occurring in calm winds, is basically generated by the radiative cooling mechanism that is established after the late afternoon transition. The analysis of night‐time surface data also showed that, under stable conditions in the case of vanishing wind speed, the friction velocity has unrealistic values that are very close to zero. This situation is undesirable for numerical models that generally use this quantity as a lower boundary condition. The analysis of night‐time temperature profiles revealed two contrasting patterns in agreement with the classical classification of radiative night (a very stable boundary layer) and a turbulent night (a weakly stable boundary layer). In contrast, the analysis of the daytime temperature profiles provided an estimation of the convective time scale that is of the order of 10 min, in agreement with experimental values. A spectral analysis and the consequent estimation of the spectral peaks under unstable and stable conditions were in agreement with literature values

Analysis of thermal and roughness effects on the turbulent characteristics of experimentally simulated boundary layers in a wind tunnel

The aim of this paper is to analyse the thermal effects in a wind tunnel experiment to simulate the planetary boundary layer (PBL). Experiments were performed in the wind tunnel of the Laboratory of Constructions Aerodynamics at the Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul State, Brazil. This wind tunnel is a closed return low-speed wind tunnel specifically designed for dynamic and static studies on civil construction models. As a novelty, one of the experimental sections of the wind tunnel was equipped with a metal sheet with Peltier elements coupled to it. In other words, thermal effects generating new flow patterns become feasible and open pathways to compare wind tunnel simulations to those in the PBL. Furthermore, measurements obtained with the smooth floor of the wind tunnel were repeated under the same conditions with the addition of the roughness in the floor, and the mechanical turbulence generated by the surface roughness significantly amplified the exchange of momentum and heat between the regions located in vertical direction of the wind tunnel boundary layer. In the presence of turbulent heat flux near the surface, thermal effects contribute to the increase of the turbulence intensity. Turbulent energy spectra for flow velocities and different heights were obtained using the Hilbert–Huang transform method, and the observed convective turbulence energy spectra behavior reproduced those measured in an unstable surface PBL

IDENTIFICAÇÃO E ESTIMATIVA DO PERÍODO DE PROCESSOS OSCILATÓRIOS NÃO TURBULENTOS NA CAMADA LIMITE ESTÁVEL ATRAVÉS DE FUNÇÕES DE AUTOCORRELAÇÃO

The autocorrelation function of the flow speed components, measures the relationship that the speed in a certain instant, has with the speed at an earlier instant. In some conditions, in the atmospheric flow, this autocorrelation presents a low frequency oscillatory shape, presenting negative lobes. This behavior is known as meandering phenomenon and becomes prevalent in low wind conditions. The objective of this study is to compare the adjustments of autocorrelation functions, present in the literature, with trial of the experimental data of FLOOSS II experiment, for determining the meandering oscillation period. Initially, three selection criteria were used to select the windows of analysis. Among the criteria the magnitude of the wind showed the most satisfactory. The fitting curves showed that both autocorrelation functions performed well, even with a large variability of oscillation periods that were found. The great variability in the oscillation period of the meandering phenomena can be associated with the nature of the physical phenomenon that is responsible for its origin. However, this hypothesis needs confirmation.A função de autocorrelação das componentes da velocidade de um escoamento, mensura a relação que a velocidade em um certoinstante possui com a velocidade em um instante anterior. Em algumas condições, no escoamento atmosférico, esta autocorrelaçãoapresenta uma forma oscilatória de baixa frequência, apresentado lobes negativos., Este comportamento é conhecido como meandroe torna-se predominante em condições de vento fraco. O objetivo deste trabalho é comparar os ajustes de funções de autocorrelações,presentes na literatura, com dados experimentais do experimento FLOOSS II para a determinação do período de oscilação domeandro. Inicialmente, três critérios de seleção foram utilizados para escolher as janelas de análise. Desntre os cirtérios, amagnitude do vento se mostrou o mais satisfatório. O ajuste das funções mostrou que ambas tiveram bom desempenho, mesmocom a grande varibilidade de períodos de oscilação encontrados. A grande variabilidade no período de oscilação do meandro podeestar associada à natureza do fenômeno responsável pela sua origem. Todavia, essa hipótese necessita de confirmação

Influência da pluma aquecida de uma chaminé no escoamento turbulento: uma abordagem inicial via simulação

Large Eddy Simulation (LES) have been employed to investigate turbulent flows. In atmospheric turbulence, this methodology is widely used and, sometimes is complementary to field experiments, leading a more detailed about turbulent flow. In this work a LES model was utilized to describe the influence exerted by a hot plume, emitted for a thermal power-plant in the atmospheric flow in the planetary boundary-layer.A Simulação dos Grandes Turbilhões (LES) é uma técnica amplamente empregada para investigar as propriedades de escoamentos turbulentos. No contexto da turbulência atmosférica, esta técnica complementa estudos experimentais, proporcionando uma descrição espacializada do escoamento. No presente trabalho um modelo LES foi aplicado para avaliar a influência da emissão de uma pluma aquecida por uma chaminé, no escoamento turbulento

IDENTIFICAÇÃO E ESTIMATIVA DO PERÍODO DE PROCESSOS OSCILATÓRIOS NÃO TURBULENTOS NA CAMADA LIMITE ESTÁVEL ATRAVÉS DE FUNÇÕES DE AUTOCORRELAÇÃO

The autocorrelation function of the flow speed components, measures the relationship that the speed in a certain instant, has with the speed at an earlier instant. In some conditions, in the atmospheric flow, this autocorrelation presents a low frequency oscillatory shape, presenting negative lobes. This behavior is known as meandering phenomenon and becomes prevalent in low wind conditions. The objective of this study is to compare the adjustments of autocorrelation functions, present in the literature, with trial of the experimental data of FLOOSS II experiment, for determining the meandering oscillation period. Initially, three selection criteria were used to select the windows of analysis. Among the criteria the magnitude of the wind showed the most satisfactory. The fitting curves showed that both autocorrelation functions performed well, even with a large variability of oscillation periods that were found. The great variability in the oscillation period of the meandering phenomena can be associated with the nature of the physical phenomenon that is responsible for its origin. However, this hypothesis needs confirmation.A função de autocorrelação das componentes da velocidade de um escoamento, mensura a relação que a velocidade em um certoinstante possui com a velocidade em um instante anterior. Em algumas condições, no escoamento atmosférico, esta autocorrelaçãoapresenta uma forma oscilatória de baixa frequência, apresentado lobes negativos., Este comportamento é conhecido como meandroe torna-se predominante em condições de vento fraco. O objetivo deste trabalho é comparar os ajustes de funções de autocorrelações,presentes na literatura, com dados experimentais do experimento FLOOSS II para a determinação do período de oscilação domeandro. Inicialmente, três critérios de seleção foram utilizados para escolher as janelas de análise. Desntre os cirtérios, amagnitude do vento se mostrou o mais satisfatório. O ajuste das funções mostrou que ambas tiveram bom desempenho, mesmocom a grande varibilidade de períodos de oscilação encontrados. A grande variabilidade no período de oscilação do meandro podeestar associada à natureza do fenômeno responsável pela sua origem. Todavia, essa hipótese necessita de confirmação

The Schistosomiasis SpleenOME: Unveiling the Proteomic Landscape of Splenomegaly Using Label-Free Mass Spectrometry

Schistosomiasis is a neglected parasitic disease that affects millions of people worldwide and is caused by helminth parasites from the genus Schistosoma. When caused by S. mansoni, it is associated with the development of a hepatosplenic disease caused by an intense immune response to the important antigenic contribution of adult worms and to the presence of eggs trapped in liver tissue. Although the importance of the spleen for the establishment of immune pathology is widely accepted, it has received little attention in terms of the molecular mechanisms operating in response to the infection. Here, we interrogated the spleen proteome using a label-free shotgun approach for the potential discovery of molecular mechanisms associated to the peak of the acute phase of inflammation and the development of splenomegaly in the murine model. Over fifteen hundred proteins were identified in both infected and control individuals and 325 of those proteins were differentially expressed. Two hundred and forty-two proteins were found upregulated in infected individuals while 83 were downregulated. Functional enrichment analyses for differentially expressed proteins showed that most of them were categorized within pathways of innate and adaptive immunity, DNA replication, vesicle transport and catabolic metabolism. There was an important contribution of granulocyte proteins and antigen processing and presentation pathways were augmented, with the increased expression of MHC class II molecules but the negative regulation of cysteine and serine proteases. Several proteins related to RNA processing were upregulated, including splicing factors. We also found indications of metabolic reprogramming in spleen cells with downregulation of proteins related to mitochondrial metabolism. Ex-vivo imunophenotyping of spleen cells allowed us to attribute the higher abundance of MHC II detected by mass spectrometry to increased number of macrophages (F4/80+/MHC II+ cells) in the infected condition. We believe these findings add novel insights for the understanding of the immune mechanisms associated with the establishment of schistosomiasis and the processes of immune modulation implied in the host-parasite interactions

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio