COMPUTATIONAL FLUID DYNAMICS TECHNIQUES FOR MULTIPHASE FLOW SYSTEMS

Mathematical modelling of multiphase flow systems has been a major and persistent challenge over the last decades. Vast attempts to obtain predictive models can be found reported in literature, where major advances can be recognized in recent years, paired to enhancements in computer science and engineering. Notwithstanding, universally valid models with a mechanistic development are far from being achieved. The current status of modelling any multiphase flow system relies on the model order reduction of purely theoretical models. Such reductions and simplifications become the source of deviations in the predictions of the experimentally measured parameters and will constrain the applicability of the models. Hence, when modelling any multiphase flow system, there is a primal need of pairing mathematical modeling and experimental studies, in order to validate the models’ predictive quality, quantifying the deviations and providing a standpoint of the applicability and limitations of the models. In this sense, a successful multiphase flow system model should provide highly accurate local predictions, have a reduced number of possible sources of deviations (i.e., reducing the number of coupled sub-models, nor relying on vast simplifications), and have a high flexibility for being adapted or optimized to different conditions. In this work, it is sought to develop highly predictive, simplified and locally validated mathematical models by applying Computational Fluid Dynamics techniques, paired with other modelling and experimental techniques. Six cases of study are developed: i) Trickle Bed Reactors (TBR), ii) Packed Bed Reactors (PBR), iii) Fluidized Bed Reactors (FBR), iv) Spouted Bed Reactors (SBR), v) Heat transfer systems enhanced by nanofluids, vi) Bubble Column Reactors (BCR) --Abstract, p. i

Tracing large-scale structures in circumstellar disks with ALMA

Planets are supposed to form in circumstellar disks. The gravitational potential of a planet perturbs the disk and leads to characteristic structures, i.e. spiral waves and gaps, in the disk's density profile. We perform a large-scale parameter study of the observability of these planet-induced structures in circumstellar disks with ALMA. On the basis of HD and MHD simulations, we calculated the disk temperature structure and (sub)mm images of these systems. These were used to derive simulated ALMA images. Because appropriate objects are frequent in Taurus, we focused on a distance of 140pc and a declination of 20{\deg}. The explored range of star-disk-planet configurations consists of 6 HD simulations (including magnetic fields and different planet masses), 9 disk sizes, 15 total disk masses, 6 different central stars, and two different grain size distributions. On almost all scales and in particular down to a scale of a few AU, ALMA is able to trace disk structures induced by planet-disk interaction or by the influence of magnetic fields on the wavelength range between 0.4 and 2.0mm. In most cases, the optimum angular resolution is limited by the sensitivity. However, within the range of typical masses of protoplanetary disks (0.1-0.001Msun) the disk mass has a minor impact on the observability. It is possible to resolve disks down to 2.67e-6Msun and trace gaps induced by a planet with M_p/M_s = 0.001 in disks with 2.67e-4Msun with a signal-to-noise ratio greater than three. The central star has a major impact on the observability of gaps, as well as the considered maximum grainsize of the dust in the disk. In general, it is more likely to trace planet-induced gaps in our MHD models, because gaps are wider in the presence of magnetic fields. We also find that zonal flows resulting from MRI create gap-like structures in the disk's re-emission radiation, which are observable with ALMA.Comment: 17 pages, 21 figure

Masdevallia hortensis

Masdevallia hortensis is similar to most other species of Masdevallia subgenus Meleagris, it can be distinguished by the callus at the apex of the dorsal sepal and the revolute, white, lateral sepals with a red-purple mid vein. For a long time known only from the type locality where it became extinct by over-collecting, it has been recently rediscovered in two other nearby localities in the Cordillera Occidental in Antioquia and Risaralda, Colombia, where it grows as an epiphyte in shaded and very humid areas of the montane forests around 2600 m elevation.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Jardín Botánico Lankester (JBL

Platystele colombiana

The relatively large flowers with long-cuadate sepals of Platystele colombiana are somewhat reminiscent of P. caudatisepala (C. Schweinf.) Garay, P. posadarum Luer & R. Escobar and P. baqueroi L. Jost & Iturralde. The new species is easily distinguished from those by the completely glandular-hirsute tepals, the very narrowly linear to acuminate petals that are about a third the width of the sepals, but almost the same in length (vs. tepals glabrous [only marginally hirsute in P. baqueroi], petals broader, at least half the width of the sepals, and less than half the length). Platystele speckmaieri Luer & Sijm is also superficially similar with its long-attenuate tepals, with sepals and petals similar in length. However, its flowers are glabrous, tepals are very narrowly caudate and the lip is broad below the middle and contracted apically.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Jardín Botánico Lankester (JBL

Andinia pseudocaulescens

Andinia pseudocaulescens has a wide distribution and has been found on all three Cordilleras in Colombia as well as in Ecuador. It frequently grows together with other species of Andinia subgen. Brachycladium (Luer) Karremans & S.Vieira-Uribe, but can be rec ognized by the small plants with elliptical leaves that are margin ally ciliate, the burgundy fowers almost as big as the leaves, borne on short inforescences, with ovate, acuminate sepals, and trans versally bilobed, pubescent petals with narrowly oblong lobes.UCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Jardín Botánico Lankester (JBL

Andinia chaoae

Descripción de Andinia chaoaeUCR::Vicerrectoría de Investigación::Unidades de Investigación::Ciencias Agroalimentarias::Jardín Botánico Lankester (JBL

Planet-induced disk structures: A comparison between (sub)mm and infrared radiation

Young giant planets, which are embedded in a circumstellar disk, will significantly perturb the disk density distribution. This effect can potentially be used as an indirect tracer for planets. We investigate the feasibility of observing planet-induced gaps in circumstellar disks in scattered light. We perform 3D hydrodynamical disk simulations combined with subsequent radiative transfer calculations in scattered light for different star, disk, and planet configurations. The results are compared to those of a corresponding study for the (sub)mm thermal re-emission. The feasibility of detecting planet-induced gaps in scattered light is mainly influenced by the optical depth of the disk and therefore by the disk size and mass. Planet-induced gaps are in general only detectable if the photosphere of the disks is sufficiently disturbed. Within the limitations given by the parameter space here considered, we find that gap detection is possible in the case of disks with masses below $\sim 10^{-4\dots-3} \, \rm M_\odot$. Compared to the disk mass that marks the lower Atacama Large (Sub)Millimeter Array (ALMA) detection limit for the thermal radiation re-emitted by the disk, it is possible to detect the same gap both in re-emission and scattered light only in a narrow range of disk masses around $\sim 10^{-4} \, \rm M_\odot$, corresponding to $16\%$ of cases considered in our study.Comment: 4 pages, 6 figure

Presence of Chlamydia, Mycoplasma, Ureaplasma, and Other Bacteria in the Upper and Lower Genital Tracts of Fertile and Infertile Populations

Objective: The genital mycoplasmas (Mycoplasma hominis and Ureaplasma urealyticum) and Chlamydia trachomatis have been implicated as possible etiologic factors in infertility. Their role in patients with infertility needs to be further defined

Multicanalidad y conflicto, análisis para algunas compañías de Colombia.

El propósito de esta investigación es identificar las variables críticas consideradas por las compañías analizadas para resolver los problemas que se presentan en la multicanalidad de distribución. La investigación es un estudio cualitativo, con entrevistas semi-estructuradas a sus altos directivos, que busca conocer las estrategias que las compañías han utilizado para el manejo de estos conflictos. Las principales causas de conflictos identificadas entre los canales de distribución fueron errores en las políticas de precio, falta de comunicación, falta de control, diferenciación del portafolio e irresponsabilidad comercial. Por otro lado, las estrategias más eficaces evidenciadas para solucionar los problemas fueron la apertura del canal de distribución directo, el mismo precio de venta al público en todos los canales, las capacitaciones a la fuerza de ventas de las compañías, la comunicación clara y la confianza entre los miembros de la cadena de distribución.The purpose of this research is to identify the critical variables considered by the companies analyzed to solve the problems that arise in multichannel distribution. The research is a qualitative study, with semi-structured interviews with their senior managers, which seeks to know the strategies that companies have used to manage these conflicts. The main causes of conflicts identified among the distribution channels were errors in price policies, lack of communication, lack of control, portfolio differentiation and commercial irresponsibility. On the other hand, the most effective strategies evidenced to solve the problems were the opening of the direct distribution channel, same sale price to the public in all the channels, training to the sales force of the companies, clear communication and trust among the members of the distribution chain

Finite element approximation of the p(⋅)p(\cdot)-Laplacian

We study a~priori estimates for the Dirichlet problem of the $p(\cdot)$-Laplacian, $$-\mathrm{div}(|\nabla v|^{p(\cdot)-2} \nabla v) = f.$$ We show that the gradients of the finite element approximation with zero boundary data converges with rate $O(h^\alpha)$ if the exponent $p$ is $\alpha$-H\"{o}lder continuous. The error of the gradients is measured in the so-called quasi-norm, i.e. we measure the $L^2$-error of $|\nabla v|^{\frac{p-2}{2}} \nabla v$