Clustering and Lagrangian statistics of bubbles

Due to their relevance and occurrence in both natural phenomena and in industrial\ud applications, the study and understanding of bubbly flows is currently an important\ud topic for fluid dynamicists. Bubble columns are commonly used in bio- and petrochemical\ud industries to enhance mixing, mass and heat transfer. In these systems, the\ud bubbles are the only energy input as there is no flow a priori. Bubble columns are also\ud referred to as pseudo-turbulence because the bubbles induce liquid fluctuations in the\ud originally quiescent liquid. These disturbances are the result of the hydrodynamic\ud interactions among the bubbles and their heterogenous distribution.\ud Turbulent flows transporting particles are ubiquitous in nature, being of such relevance\ud in diverse fields ranging from atmospheric physics to oceanography. Usually\ud the convected particles have a different density and size than the transporting fluid,\ud turbulent bubbly flows are a particular case of them. In recent years, Lagrangian\ud studies—i.e. studies following the particle motion—of particles in turbulence have\ud gained considerable attention because this approach is closer to the inherent mixing\ud and transport characteristic of turbulence. Yet there is still the challenge and interest\ud to comprehend more the Lagrangian statistics of particles in turbulence.\ud This work studies bubbly flows in two different flow conditions. In the first part,\ud we study the pseudo-turbulence induced by rising bubbles in quiescent liquid. In the\ud second part, we study the Lagrangian statistics and clustering of micro-bubbles in\ud homogeneous isotropic turbulence

Three-dimensional Lagrangian Voronoi analysis for clustering of particles and bubbles in turbulence

Three-dimensional Voronoi analysis is used to quantify the clustering of inertial particles in homogeneous isotropic turbulence using data from numerics and experiments. We study the clustering behavior at different density ratios and particle response times (i.e. Stokes numbers St). The Probability Density Functions (PDFs) of the Voronoi cell volumes of light and heavy particles show a different behavior from that of randomly distributed particles -i.e. fluid tracers-implying that clustering is present. The standard deviation of the PDF normalized by that of randomly distributed particles is used to quantify the clustering. Light particles show maximum clustering for St around 1-2. The results are consistent with previous investigations employing other approaches to quantify the clustering. We also present the joint PDFs of enstrophy and Voronoi volumes and their Lagrangian autocorrelations. The small Voronoi volumes of light particles correspond to regions of higher enstrophy than those of heavy particles, indicating that light particles cluster in higher vorticity regions. The Lagrangian temporal autocorrelation function of Voronoi volumes shows that the clustering of light particles lasts much longer than that of heavy or neutrally buoyant particles. Due to inertial effects, the Lagrangian autocorrelation time-scale of clustered light particles is even longer than that of the enstrophy of the flow itself.Comment: J. Fluid Mech. 201

On bubble clustering and energy spectra in pseudo-turbulence

3D-Particle Tracking (3D-PTV) and Phase Sensitive Constant Temperature Anemometry in pseudo-turbulence--i.e., flow solely driven by rising bubbles-- were performed to investigate bubble clustering and to obtain the mean bubble rise velocity, distributions of bubble velocities, and energy spectra at dilute gas concentrations ($\alpha \leq2.2$%). To characterize the clustering the pair correlation function $G(r,\theta)$ was calculated. The deformable bubbles with equivalent bubble diameter $d_b=4-5$ mm were found to cluster within a radial distance of a few bubble radii with a preferred vertical orientation. This vertical alignment was present at both small and large scales. For small distances also some horizontal clustering was found. The large number of data-points and the non intrusiveness of PTV allowed to obtain well-converged Probability Density Functions (PDFs) of the bubble velocity. The PDFs had a non-Gaussian form for all velocity components and intermittency effects could be observed. The energy spectrum of the liquid velocity fluctuations decayed with a power law of -3.2, different from the $\approx -5/3$ found for homogeneous isotropic turbulence, but close to the prediction -3 by \cite{lance} for pseudo-turbulence

DETERMINACIÓN DE LA LÍNEA BASE PARA EL SG-SST EN LA EMPRESA GIDSER S.A.S

La implementación del Sistema de Gestión de Seguridad y Salud en el Trabajo SG-SST, le permite a una empresa tener una mejoría de las condiciones de trabajo y salud y de la productividad, mediante la coordinación de acciones para promover la salud, prevenir y controlar los riesgos. El objetivo es realizar una línea base en Seguridad y Salud en el Trabajo de la empresa GIDSER S.A.S, ubicada en Cartagena. Se trata de una investigación de tipo descriptivo con enfoque mixto, que consta de la realización de una consultoría. Se realizaron entrevistas por medio de video llamadas y llamadas telefónicas a los empleados. En la evaluación inicial se identificó que la población no presenta enfermedad laboral. Se evaluaron los 7 estándares mínimos de cumplimiento del Sistema de Gestión y Seguridad en el Trabajo SG-SST según lo establecido en la resolución 0312 de 2019 y se encontró que solo cumplieron con la afiliación al sistema de seguridad social integral. Posteriormente al evaluar la guía técnica colombiana 45, se encontró exposición a riesgos biológicos debido a la manipulación de partículas corporales en la toma de muestra, a riesgos químicos por la manipulación de reactivos de laboratorio y sustancias para el lavado de superficies y materiales, a riesgos psicosociales por el estrés generado por las rutinas de trabajo, y a riesgos de condiciones de seguridad por la utilización de equipos biomédicos. Esto condujo a la elaboración de unos productos para el diseño e implementación de un Sistema de Gestión de la Seguridad y Salud en el trabajo

Ultrasound-guided insertion of intra-aortic balloon counterpulsation in intensive care: description of the technique

Intra-aortic balloon counterpulsation (IAoBC) is a mechanical circulatory support device that has been used for more than 50 years, mainly for cardiogenic shock. Although its effect on mortality is controversial, IAoBC is still used in a wide variety of pre- and postoperative clinical settings in cardiac surgery centers. IAoBC has a complication rate of approximately 30%, mostly associated with problems during insertion and malpositioning. Thus, an insertion technique based on the use of ultrasound at the patient’s bedside in the intensive care unit (ICU) is proposed. © 2020, The Author(s)

Clonal chromosomal mosaicism and loss of chromosome Y in elderly men increase vulnerability for SARS-CoV-2

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) had an estimated overall case fatality ratio of 1.38% (pre-vaccination), being 53% higher in males and increasing exponentially with age. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, we found 133 cases (1.42%) with detectable clonal mosaicism for chromosome alterations (mCA) and 226 males (5.08%) with acquired loss of chromosome Y (LOY). Individuals with clonal mosaic events (mCA and/or LOY) showed a 54% increase in the risk of COVID-19 lethality. LOY is associated with transcriptomic biomarkers of immune dysfunction, pro-coagulation activity and cardiovascular risk. Interferon-induced genes involved in the initial immune response to SARS-CoV-2 are also down-regulated in LOY. Thus, mCA and LOY underlie at least part of the sex-biased severity and mortality of COVID-19 in aging patients. Given its potential therapeutic and prognostic relevance, evaluation of clonal mosaicism should be implemented as biomarker of COVID-19 severity in elderly people. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, individuals with clonal mosaic events (clonal mosaicism for chromosome alterations and/or loss of chromosome Y) showed an increased risk of COVID-19 lethality

Asedios al archivo, la literatura, los territorios, las pedagogías y la creación

Lenguajes de la memoria y los Derechos Humanos III. Asedios al archivo, la literatura, los territorios, las pedagogías y la creación está integrado por un conjunto de trabajos cuyos ejes temáticos son auscultados desde el suelo presente, necesario, insistente, heteroglósico, en continua redefinición. El libro fue concebido en un momento atravesado por el influjo del abismo producido por el gobierno de la derecha en Argentina y en América Latina, en el interregno 2015-2019, y culminado durante la pandemia Covid 19, que azota al mundo con millones de muertos e infectados.Fil: Ares, María Cristina. Universidad de Buenos Aires. Departamento de Letras; Argentina.Fil: Bracaccini Acevedo, María. Universidad Nacional de Córdoba. Facultad de Filosofía y Humanidades; Argentina.Fil: Cella, Susana. Universidad de Buenos Aires. Facultad de Filosofía y Letras; Argentina.Fil: Cornavaca, María Trinidad. Universidad Nacional de Córdoba. Facultad de Lenguas; Argentina.Fil: Corral, María Manuela. Universidad Nacional de Córdoba. Facultad de Lenguas; Argentina.Fil: Crenzel, Emilio. Universidad de Buenos Aires. Facultad de Ciencias Sociales; Argentina.Fil: Da Silva Catela, Ludmila. Universidad Federal de Río de Janeiro; Brasil.Fil: Díaz, Marcelo. Universidad Nacional de Río Cuarto; Argentina.Fil: Ferraro, Paula Daniela. Universidad Federal Fluminense; Brasil.Fil: Ferrada Rau, Rocío Nili. Universidad de Chile; Chile.Fil: Garbero, Vanesa. Universidad de Buenos Aires; Argentina.Fil: García, Díaz. Universidad Nacional Autónoma de México; México.Fil: Giraldi Dei Cas, Norah. Universidad de Lille; Francia.Fil: Gutiérrez, Carlos Arturo. Universidad Nacional de Colombia; Colombia.Fil: Kozameh, Alicia. Chapman University. Departamento de Inglés; Estados Unidos.Fil: Magrin, Natalia. Universidad Nacional de Córdoba. Facultad de Psicología; Argentina.Fil: Inchauspe, Leandro. Universidad Nacional de Córdoba. Facultad de Filosofía y Humanidades. Escuela de Historia; Argentina.Fil: Martínez, Carlos Dámaso. Universidad Nacional de Córdoba. Facultad de Filosofía y Humanidades. Escuela de Letras; Argentina.Fil: Mercado, Mónica. Universidad Nacional de Córdoba. Facultad de Artes. Departamento Académico de Artes Visuales; Argentina.Fil: Merro, Agustina. Universidad Nacional de Córdoba. Facultad de Filosofía y Humanidades. Escuela de Letras; Argentina.Fil: Mohaded, Ana. Universidad Nacional de Córdoba. Facultad de Artes. Departamento Académico de Cine y Televisión; Argentina.Fil: Montes, Alicia. Universidad de Buenos Aires. Facultad de Filosofía y Letras; Argentina.Fil: Muñoz Leppe, Olga Elvira. Universidad Metropolitana de Ciencias de la Educación; Chile.Fil: Palma Solís, Jennifer Luz. Universidad de Chile; Chile.Fil: Pino, Mirian. Universidad Nacional de Córdoba. Facultad de Filosofía y Humanidades. Escuela de Letras; Argentina.Fil: Rabanal Gatica, Damaso. Universidad Austral de Chile; Chile.Fil: Reati, Fernando. Georgia State University; Estados Unidos.Fil: Reyes, Manuela. Universidad Nacional de Villa María; Argentina.Fil: Rocchietti, Luciana. Universidad Nacional de Córdoba. Facultad de Ciencias de la Comunicación; Argentina.Fil: Saint Bonet, María Virginia. Universidad Nacional de Córdoba. Facultad de Filosofía y Humanidades. Escuela de Letras; Argentina.Fil: Schwenke, Gonzalo. Universidad Austral de Chile; Chile.Fil: Semilla Durán, María Angélica. Universidad Central de Barcelona; España.Fil: Solis, Ana Carol. Universidad Nacional de Córdoba. Facultad de Filosofía y Humanidades. Escuela de Historia; Argentina.Fil: Sosa San Martín, Gabriela. Universidad de la República. Facultad de Humanidades y Ciencias de la Educación; Uruguay.Fil: Suppo, Carina Noemí. Universidad Nacional de Rosario; Argentina.Fil: Vásquez, Malva Marina. Universidad de Chile; Chile.Fil: Vassallo, Celeste. Universidad Nacional de Córdoba. Facultad de Filosofía y Humanidades. Escuela de Letras; Argentina.Fil: Wild, Carolina. Universidad Nacional de Córdoba. Facultad de Ciencias de la Comunicación; Argentina

Gestión del conocimiento: perspectiva multidisciplinaria. Volumen 12

El libro “Gestión del Conocimiento. Perspectiva Multidisciplinaria”, Volumen 12, de la Colección Unión Global, es resultado de investigaciones. Los capítulos del libro, son resultados de investigaciones desarrolladas por sus autores. El libro cuenta con el apoyo de los grupos de investigación: Universidad Sur del Lago “Jesús María Semprúm” (UNESUR), Zulia – Venezuela; Universidad Politécnica Territorial de Falcón Alonso Gamero (UPTAG), Falcón – Venezuela; Universidad Politécnica Territorial de Mérida Kleber Ramírez (UPTM), Mérida – Venezuela; Universidad Guanajuato (UG) - Campus Celaya - Salvatierra - Cuerpo Académico de Biodesarrollo y Bioeconomía en las Organizaciones y Políticas Públicas (C.A.B.B.O.P.P), Guanajuato – México; Centro de Altos Estudios de Venezuela (CEALEVE), Zulia – Venezuela, Centro Integral de Formación Educativa Especializada del Sur (CIFE - SUR) - Zulia - Venezuela, Centro de Investigaciones Internacionales SAS (CIN), Antioquia - Colombia.y diferentes grupos de investigación del ámbito nacional e internacional que hoy se unen para estrechar vínculos investigativos, para que sus aportes científicos formen parte de los libros que se publiquen en formatos digital e impreso

Energy spectra and bubble velocity distributions in pseudo-turbulence: Numerical simulations vs. experiments

Direct numerical simulations (DNS) are performed to study the behavior of a swarm of rising air bubbles in water, employing the front tracking method, which allows to handle finite-size bubbles. The swarms consist of monodisperse deformable 4 mm bubbles with a gas fraction of 5% and 15%. This paper focuses on the comparison of the liquid energy spectra and bubble velocity probability density functions (PDFs) with experimental data obtained by phase-sensitive constant-temperature anemometry (CTA) and three-dimensional particle tracking velocimetry (PTV), respectively.\ud \ud The numerical simulations confirm that the spectra of the velocity fluctuations driven by the rising bubbles follow a power law with slope close to −3, supporting the idea that the dissipation of the bubble wake is the origin of this spectral scaling, as previously proposed by Lance and Bataille.\ud \ud The computed PDFs of the bubble velocity show non-Gaussian features, as is also observed in the experiments. The agreement with experimental measurements is especially good in the peak region, whereas the tails of the experimental PDFs show more intermittency in comparison to the numerical results. This can be explained by the lack of large-scale flow structures in the simulations, and by the large difference in measurement time\u

Acceleration statistics of light particles in turbulence

We report results from the first systematic Lagrangian experimental investigation in the previously unexplored regime of light (air bubbles in water, and rigid hollow spheres) and large particles (D/η >> 1) in turbulence [1]. Using a traversing camera setup and particle tracking, we study the Lagrangian acceleration statistics of ∼3 mm diameter (D) bubbles in a water tunnel with nearly homogeneous and isotropic turbulence generated by an active-grid. The Reynolds number (Reλ) is varied from 145 to 230, resulting in size ratios, D/η in the range of 7.3-12.5, where η is the Kolmogorov length scale. The experimental results are closely matched by numerical simulations of finite-size bubbles with the Faxén corrections. We also report preliminary results on light rigid spheres in turbulence