Flow around a hemisphere-cylinder at high angle of attack and low Reynolds number. Part II: POD and DMD applied to reduced domains

Three-dimensional direct numerical simulations (DNS) have been performed on a finite-size hemispherecylinder model at angle of attack AoA = 20◦ and Reynolds numbers Re = 350 and 1000. Under these conditions, massive separation exists on the nose and lee-side of the cylinder, and at both Reynolds numbers the flow is found to be unsteady. Proper orthogonal decomposition (POD) and dynamic mode decomposition (DMD) are employed in order to study the primary instability that triggers unsteadiness at Re = 350. The dominant coherent flow structures identified at the lower Reynolds number are also found to exist at Re = 1000; the question is then posed whether the flow oscillations and structures found at the two Reynolds numbers are related. POD and DMD computations are performed using different subdomains of the DNS computational domain. Besides reducing the computational cost of the analyses, this also permits to isolate spatially localized oscillatory structures from other, more energetic structures present in the flow. It is found that POD and DMD are in general sensitive to domain truncation and noneducated choices of the subdomain may lead to inconsistent results. Analyses at Re = 350 show that the primary instability is related to the counter rotating vortex pair conforming the three-dimensional afterbody wake, and characterized by the frequency St ≈ 0.11, in line with results in the literature. At Re = 1000, vortex-shedding is present in the wake with an associated broadband spectrum centered around the same frequency. The horn/leeward vortices at the cylinder lee-side, upstream of the cylinder base, also present finite amplitude oscillations at the higher Reynolds number. The spatial structure of these oscillations, described by the POD modes, is easily differentiated from that of the wake oscillations. Additionally, the frequency spectra associated with the lee-side vortices presents well defined peaks, corresponding to St ≈ 0.11 and its few harmonics, as opposed to the broadband spectrum found at the wake.

Flow around a hemisphere-cylinder at high angle of attack and low Reynolds number. Part I: Experimental and numerical investigation

Three-dimensional Direct Numerical Simulations combined with Particle Image Velocimetry experiments have been performed on a hemisphere-cylinder at Reynolds number 1000 and angle of attack 20◦. At these flow conditions, a pair of vortices, so-called “horn” vortices, are found to be associated with flow separation. In order to understand the highly complex phenomena associated with this fully threedimensional massively separated flow, different structural analysis techniques have been employed: Proper Orthogonal and Dynamic Mode Decompositions, POD and DMD, respectively, as well as criticalpoint theory. A single dominant frequency associated with the von Karman vortex shedding has been identified in both the experimental and the numerical results. POD and DMD modes associated with this frequency were recovered in the analysis. Flow separation was also found to be intrinsically linked to the observed modes. On the other hand, critical-point theory has been applied in order to highlight possible links of the topology patterns over the surface of the body with the computed modes. Critical points and separation lines on the body surface show in detail the presence of different flow patterns in the base flow: a three-dimensional separation bubble and two pairs of unsteady vortices systems, the horn vortices, mentioned before, and the so-called “leeward” vortices. The horn vortices emerge perpendicularly from the body surface at the separation region. On the other hand, the leeward vortices are originated downstream of the separation bubble, as a result of the boundary layer separation. The frequencies associated with these vortical structures have been quantified.

Estudio molecular en dos hermanas afectadas por ictiosis congénita autosómica recesiva : descripción de una nueva mutación causal en TGM1

Se describe la variante homocigota c.320-2A>G de TGM1 en dos hermanas con ictiosis congénita autosómica recesiva. El clonaje de los transcritos generados por esta variante permitió identificar tres mecanismos moleculares de splicing alternativos.

Biomarker evaluation and toxicological study of essential oils of Foeniculum vulgare and Calamintha nepeta

The aim of this study was to evaluate the toxicological properties of EOs of F. vulgare and C. nepeta, widespread in Mediterranean agrosilvopastoral systems and often used as food condiments in Alentejo. EOs were obtained from aerial part of plants by hydrodistillation and chemical composition was evaluated by GC-FID. Toxicity of essential oils was evaluated by the estimation of LC50 in brine shrimp and LD50 in mice. Oral toxicity assays were performed in mice. Histological analyses and quantification of biomarkers aspartate aminotransferase (AST), alanine aminotransferase (ALT), alkaline phosphatase (ALP), gamma glutamyltransferase (γ-GT), bilirubin, creatinine and urea were performed for monitoring liver and kidney functions. the EOs of C. nepeta and F. vulgare showed very low toxicity suggesting their potential use as food supplement. Additionally, our studies point out the importance of the integration of C. nepeta and F. vugare in silvopastoral agroforestry systems, contributing to the animal health and profitability of livestock.

ESTIMACIÓN DE LA ISLA DE CALOR EN SANTA TERESITA, PARTIDO DE LA COSTA, PROVINCIA DE BUENOS AIRES, ARGENTINA

En los últimos años, la modificación que el medio urbano ejerce sobre el clima regional a una escala local, la llamada isla de calor urbana, ha sido uno de los fenómenos más estudiados, dado que tiene una relación directa con el confort y la calidad de vida de la población. Es por ello que el presente trabajo tiene por objeto presentar los primeros resultados de la estimación la isla de calor urbana en Santa Teresita, una localidad balnearia ubicada en el centro este de la provincia de Buenos Aires, a los 33º 33´ 00´´ S y 56º 41´ 00´´ O. La ciudad ha nacido y crecido con un fin turístico asociado al clima templado oceánico y a sus atractivas playas. Se efectuaron mediciones de temperatura del aire y humedad relativa a través de la ciudad para determinar la forma y la intensidad de la isla de calor urbano utilizando estaciones móviles e información de una estación meteorológica fija y datos del Servicio Meteorológico Nacional. La ciudad presenta una variación climática generada por las edificaciones, la incidencia del mar y de la vegetación, diferente a lo largo del día.Palabras Clave: Isla de calor urbana – Temperatura - Humedad relativa - Santa Teresita, ArgentinaAbstracIn the last years, the modification that the urban way exercises on the regional climate to a local scale, the so called urban heat island, has been one of the most studied phenomena ast it has a direct relation with the comfort and quality of life of the population. It is for it that the present work takes as an object present the initial results of estimating the urban heat island in Santa Teresita, a touristic locality located in the central eastern province of Buenos Aires, the 33º 3 ‘00 “ S and 56º40‘00 “ W. The city was born and grew up with a tourism associated with the moderate oceanic climate and with their attractive beaches. There were effected measurements of temperature of the air and relative dampness across the city to determine the form and the intensity of the urban heat island using mobile stations and information from a wheater station data sets and the Meteorological National Service. The city has a diverged climate generated by the buildings, the incident of the sea and of the vegetation, different throughout the day.Key words: Urban heat island - Temperature - Relative dampness - Santa Teresita, Argentina.