Examinando por Materia "DINAMICA DE FLUIDOS"

Mostrando1 - 11 de 11
  • Artículo de Publicación Periódica
    A combined experimental-computational approach for spatial protection efficacy assessment of controlled release devices against mosquitoes (Anopheles)
    (2018-03) Bernier, Ulrich R.; Kline, Daniel L.; Abad Vázquez, Agustín; Perry, Melynda; Cohnstaedt, Lee W.; Gurman, Pablo; D'hers, Sebastián; Elman, Noel M.
    "This work describes the use of entomological studies combined with in silico models (computer simulations derived from numerical models) to assess the efficacy of a novel device for controlled release of spatial repellents. Controlled Release Devices (CRDs) were tested with different concentrations of metofluthrin and tested against An. quadrimaculatus mosquitoes using arm-in cage, semi-field, and outdoor studies. Arm-in-cage trials showed an approximate mean values for mosquito knockdown of 40% and mosquito bite reduction of 80% for the optimal metofluthrin formulation for a 15-minute trial. Semi-field outdoor studies showed a mean mortality of a 50% for 24 hour trial and 75% for a 48 hour trial for optimal concentrations. Outdoors studies showed an approximate mean mortality rate of 50% for a 24 hour trial for optimal concentrations. Numerical simulations based on Computational Fluid Dynamics (CFD) were performed in order to obtain spatial concentration profiles for 24 hour and 48 hour periods. Experimental results were correlated with simulation results in order to obtain a functional model that linked mosquito mortality with the estimated spatial concentration for a given period of time. Such correlation provides a powerful insight in predicting the effectiveness of the CRDs as a vector-control tool. While CRDs represent an alternative to current spatial repellent delivery methods, such as coils, candles, electric repellents, and passive emanators based on impregnated strips, the presented method can be applied to any spatial vector control treatment by correlating entomological endpoints, i.e. mortality, with in-silico simulations to predict overall efficacy. The presented work therefore presents a new methodology for improving design, development and deployment of vector-control tools to reduce transmission of vector-borne diseases, including malaria and dengue."
  • Artículo de Publicación Periódica
    Controlled release spatial repellent devices (CRDs) as novel tools against malaria transmission: a semi‑field study in Macha, Zambia
    (2018-11) Stevenson, Jennifer C.; Simubali, Limonty; Mudenda, Twig; Cardol, Esther; Bernier, Ulrich R.; Abad Vázquez, Agustín; Thuma, Philip E.; Norris, Douglas E.; Perry, Melynda; Kline, Daniel L.; Cohnstaedt, Lee W.; Gurman, Pablo; D'hers, Sebastián; Elman, Noel M.
    "The emergence of mosquitoes that can avoid indoor-deployed interventions, such as treated bed nets and indoor residual spraying, threatens the mainstay of malaria control in Zambia. Furthermore, the requirement for high coverage of these tools poses operational challenges. Spatial repellents are being assessed to supplement these vector control tools, but limitations exist in the residual effect of the repellent and the need for external power or heat for diffusion of the volatiles."
  • Proyecto final de Grado
    Desarrollo del modelo aerodinámico del Fórmula SAE 2012
    (2018) Scomazzon, Nicolás Andrés; Raffo, Federico; Zubiri, Juan Ignacio
    "El Fórmula SAE ITBA fue desarrollado y construido por alumnos de la Universidad a lo largo de los años. En las sucesivas etapas del proyecto se diseñaron los distintos componentes y sistemas del vehículo, pero nunca hasta el momento se había realizado un análisis aerodinámico. En base a ello, este trabajo busca mostrar cómo generar un modelo computacional que pueda ser utilizado para realizar el mencionado análisis y obtener conclusiones en cuanto a las cargas aerodinámicas y los distintos flujos de aire de interés que existen sobre el vehículo. Estos objetivos se buscarán cumplir mediante la implementación de un análisis Computational Fluid Dynamics (CFD)."
  • Tesis de maestría
    Development of an empirical body force model for plasma-based flow control in CFD applications
    (2020) Günther, Maiken; Frohnapfel, Bettina; Kriegseis, Jochen
    In the present work a new empirical model for the phase-resolved body forces of an DBD (Dielectric-Barrier-Discharge)-plasma actuator is developed. Therefore planar body forces have been derived from existing PIV (Particle-Image Velocimetry) measurements. A new approach is introduced that makes use of the similarity of fluid dynamic and electrostatic potential theory. The body forces are derived with the gradient of a scalar potential field that consists of superimposed single body force potentials. A system of linear equations describes the relation between the gradient field, the magnitude of the single potentials and the resulting body forces. A least-square fit of this equation system to the experimental body forces approximates the local magnitude of the potentials. The modeling results are compared to the experimental data regarding their phase-averaged and phase-resolved integral body force, the spatial body force distribution and the physical plausibility of the potential magnitudes. Centering around a baseline state, different numeric configurations of the model and their results are presented and discussed. This baseline state strongly indicates the validity of the developed approach, particularly regarding the resulting values of phase-resolved integral body forces. A future improvement of the numeric setup of the model is expected to prove the similarity of the distribution of body force potentials and free charges in the discharge area. This could lead towards a model that is independent from experimental validations. Finally, the new model is drawn into comparison with former modeling approaches by Shyy et al. [28], Suzen et al. [31] and Maden et al. [23]. Here it asserts itself with its unique capability to represent both components of phase-resolved body forces with good accuracy.
  • Tesis de maestría
    Evaluation of StarCCM+ to predict thermoacoustic instabilities using Large Eddy Simulation
    (2017) Indlekofer, Thomas; Ariatabar, Behdad; Bauer, Hans-Jörg; Hermeth, Sebastian
    "Self-sustained pressure and heat-release oscillations yielded by thermoacoustic coupling are a major problem of gas turbine operation and methods to predict them are needed. This work investigates the capabilities of Large Eddy Simulation (LES) in StarCCM+ to predict these instabilities in the academic Volvo bluff-body combustor. First, simplified cases are studied to assess boundary condition treatment and numerical accuracy of the methods available. The non-reactive operating point is predicted accurately, showing good agreement for velocity fields as well as the ability to predict the vortex shedding frequency in the intrinsically unsteady region of the recirculation zone. For a reacting-stable operating point the acceleration downstream of the bluff body is overpredicted and the flow fields are not predicted accurately. Low frequency oscillations of the unstable operating points are evidenced coincididing with experimental results and an acoustic analysis based on Comsol Multiphysics. Up to = 1:0 the coherence of the equivalence ratio and the magnitude of the instabilities is predicted qualitatively."
  • Tesis de maestría
    Experimental investigation of air entrainment by a vertical jet plunging into a liquid pool
    (2018) Büttner, Fabian; Schulenberg, Thomas; Gabriel, Stephan; Kuhn, Dietmar
    "The aim of the work is the investigation of the liquid flow field that is induced by the jet inside the receiving pool and the simultaneous observation of the gaseous phase. The applied meas-urement techniques were Particle Image Velocimetry (PIV) for analysing the liquid flow field and shadowgraph imaging, which enables a study of the dispersed air bubbles. Furthermore, all boundary conditions that influence the experiment were recorded."
  • Artículo de Publicación Periódica
    Influence of bottleneck lengths and position on simulated pedestrian egress
    (2017-01) Parisi, Daniel; Patterson, Germán
    "In this paper, the problem of pedestrian egress under di erent geometries is studied by means of two numerical models. The length of the bottleneck after the exit and the distance of the exit to the lateral wall of a squared room are investigated. Both models show that an increase in the bottleneck length increases the evacuation time by more than 20%, for any exit position. Hence, a bottleneck length tending to zero is the best choice. On the contrary, the results of moving the exit closer to the lateral wall are different in both models and, thus, its convenience cannot be stated. To unveil whether this layout modi cation is favorable, experimental data are required. Moreover, the discrepancy between models indicates that they should be validated considering several scenarios."
  • Artículo de Publicación Periódica
    Microfluidic device concept based on microoscillator dynamics at a liquid–liquid interface
    (2008) Allievi, Alejandro
    "Oscillating microbeams and microplates have been used extensively as sensing components for property detection in fluids. In liquids, their quality factor Q is drastically decreased, thus affecting a microsensor’s resolution. To improve the Q-factor, we present a novel concept based on the positive use of surface tension on a mechanical oscillator composed of a microbeam–microplate assembly suspended at a liquid–liquid interface in a microfluidic channel. An analytical model is developed to investigate rotational dynamics of such an assembly..."
  • Artículo de Publicación Periódica
    Rapid reconstitution packages (RRPs) for stable storage and delivery of glucagon
    (2019-06) D'hers, Sebastián; Abad Vázquez, Agustín; Gurman, Pablo; Elman, Noel M.
    "Current emergency injectors of glucagon require manual reconstitution, which involves several steps that may lead to dosage errors. Rapid reconstitution packages (RRPs) are new devices, designed using computational fluid dynamics (CFD) to optimize fluid mixing, integrating physical properties of active pharmaceutical ingredients (APIs), excipients and diluents. RRPs improve drug stability for long-term storage and ease of delivery. Device prototypes were manufactured using advanced stereolithography apparatus (SLA) 3D printing technology. Reconstitution of glucagon with RRPs was evaluated by highperformance liquid chromatography (HPLC) and optical spectroscopy methods. Enzyme-linked immunosorbent assays were performed to test in vitro activity. Experimental results showed that RRPs effectively reconstituted glucagon even after exposure to 60 °C for a 24-h period. RRPs exhibited improved performance at maintaining drug stability compared to lyophilized glucagon stored in a standard glass vial under the same temperature conditions. RRPs represent a portable platform for rapid reconstitution of lyophilized drugs, compatible with standard syringes available in any clinical setting. The RRP provides an alternative to manual reconstitution process, especially designed for medical emergencies."
  • Tesis de maestría
    Re-engineering of Pelton runner hydraulic cfd profile to systemize the Fabrication process in Software to include hydraulic tests design & manufacturing
    (2020) Stellner, Julia; Guerra, Carlos
    Uno de los objetivos del Centro de Investigación y Recuperación de Turbinas hidráulicas y Partes Industriales (CIRT) que pertenece a un holding estatal llamado CORPORACIÓN ELÉCTRICA DEL ECUADOR - CELEC EP con la unidad de negocios Hidroagoyán, es la reparación y reconstrucción de turbinas y piezas de repuesto que forman parte de una central hidroeléctrica. La meta es remediar los defectos y desgastes ocasionados durante la operación y llevar los componentes a su estado nominal o bien, mejorar el perfil hidráulico para obtener un funcionamiento adecuado con menos fallas. Los rodetes recuperados del CIRT llegan de todas partes del país que se pueden clasificar por los tipos Kaplan, Francis y Pelton. La turbina Pelton, a pesar de ser una tecnología relativamente antigua, tiene un estado de investigación y comprensión del funcionamiento comparativamente bajo. Durante años el desarrollo de la turbina Pelton continuó y se logró mejorar el funcionamiento, siendo una de las turbinas hidráulicas más eficientes hoy en día. Sin embargo, la comprensión más profunda de los mecanismos de flujo durante la interacción del chorro con el cangilón todavía no se ha logrado, ya que se trata de un flujo complejo. Por causa de las complejidades se pueden realizar simulaciones con Dinámica de Fluidos Computacionales (CFD por sus siglas en inglés) sin embargo estas presentan dificultades tecnológicas y en algunos casos imprecisiones. Es por ello que hoy en día, aún se realizan los estudios acerca de la tecnología Pelton en un banco de pruebas que produce un costo alto y un tiempo de ensayos y estudios prolongado. En muchos de los casos los rodetes llegan al CIRT sin planos dimensionales o debido a la complejidad propia de su perfil hidráulico no se puede plasmar en un documento 2D, tal caso requiere el proceso de una ingeniería inversa; para automatizar, simplificar y reducir el tiempo del proceso de diseño, un programa para la sistematización del diseño fue desarrollado, lo cual ayuda en el proceso de la ingeniería inversa, como en el rediseño de rodetes fallados. Este programa aporta a la solución de la dificultad de la simulación de los cangilones, lo cual genera perfiles hidráulicos de cangilones Pelton con características deseadas de manera automática cuya ventaja principal es la creación de modelos simples y modificables de forma rápida para su uso en pruebas de flujo en CFD, con los cuales la obtención de resultados de la idoneidad del perfil y las dimensiones del cangilón es lograda. Los diseños virtuales de los cangilones de la central Pucará – Ecuador sirven como base de diseño del programa. En la evolución del trabajo un rango de buen funcionamiento de 15 a 20% de diferencia del tamaño entre Pucará y el cangilón modelado fue establecido.
  • Artículo de Publicación Periódica
    Simulating competitive egress of noncircular pedestrians
    (2017-04) Cruz Hidalgo, R.; Parisi, Daniel; Zuriguel, Iker
    "We present a numerical framework to simulate pedestrian dynamics in highly competitive conditions by means of a force-based model implemented with spherocylindrical particles instead of the traditional, symmetric disks. This modification of the individuals’ shape allows one to naturally reproduce recent experimental findings of room evacuations through narrow doors in situations where the contact pressure among the pedestrians was rather large. In particular, we obtain a power-law tail distribution of the time lapses between the passage of consecutive individuals. In addition, we show that this improvement leads to new features where the particles’ rotation acquires great significance."