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InSight landed < 550km from the Mars Science Laboratory rover. Both missions carried a suite of meteorological instruments, but MSL’s wind sensor was damaged on landing and failed after ~two Mars years [1]. This made it difficult to characterize the diurnal and seasonal cycles of winds in Gale Crater. Fortunately, InSight’s wind sensor is returning good wind data for the landing season (Ls~300°, northern winter). A complementary presentation provides a detailed look at the observed diurnal cycle of InSight winds and its variability [2].\ud \ud Here, we use atmospheric models, primarily the MarsWRF multi-scale model, run at ~km to 5km scale resolution over the MSL/InSight region, to provide predictions based on our current understanding of the underlying physics. We then improve the models by modifying them to better match the circulation at InSight in northern winter, and use these results to better understand the circulation in Gale Crater. Finally, we extend our simulations over a full Mars year to provide insight into the orientation, morphology, and migration of aeolian features in the vicinity of InSight and MSL.\ud \ud In this region, the large-scale circulation is largely controlled by the seasonal Hadley circulation, with near-surface winds blowing from ~south to north in northern summer and ~north to south in winter. Both landing sites also sit on or close to the hemispheric dichotomy boundary, resulting in daytime upslope flows (from ~north to south) and nighttime downslope flows (from ~south to north); these tend to enhance the Hadley circulation during the daytime in northern winter and at night in summer.\ud \ud For InSight’s location, most models predict winds from between the ~north and west virtually all sol in northern winter [e.g. 3], although there is more model-to-model variation in wind speed. In Gale Crater, however, the situation is complicated by the presence of very large topographic gradients. For example, models suggest that in northern winter the ~north-to-south Hadley circulation winds are enhanced at night by strong downslope winds on the northern rim slopes, resulting in very strong winds at MSL’s location [e.g. 4].\ud \ud Our goal is to develop a model of the seasonal cycle of winds over the entire region which simultaneously matches the InSight and partial MSL wind datasets and the observed aeolian features. Unfortunately, while evidence points toward most aeolian activity near MSL occurring in northern winter at night [5], MSL’s wind sensor was unable to measure nighttime winds well [1]. By measuring regional winds over the full diurnal cycle in northern winter, InSight wind data allow us to (i) directly measure the winds approaching Gale Crater from the ~north, (ii) constrain and improve MarsWRF and other models, and hence (iii) better understand the true nature of the winds and aeolian processes in Gale Crater and over the entire region.\ud \ud [1] Newman, C. E. et al. (2017) Icarus, 291, 203–231. \ud [2] Viúdez-Moreiras, D. et al. (2019) EGU. \ud [3] Spiga et al. (2018) SSR, 214:109. \ud [4] Pla-Garcia, J. et al. (2016), Icarus, 280, 103-113. \ud [5] Viúdez-Moreiras, D. et al. (2019), Icarus, 319, 909-925.

A hybrid Eulerian-Lagrangian approach is employed to simulate heavy particle dispersion in turbulent pipe flow. The mean flow is provided by the Eulerian simulations developed by mean of JetCode, whereas the fluid fluctuations seen by particles are prescribed by a stochastic differential equation based on normalized Langevin. The statistics of particle velocity are compared to LES data which contain detailed statistics of velocity for particles with diameter equal to 20.4 µm. The model is in good agreement with the LES data for axial mean velocity whereas rms of axial and radial velocities should be adjusted.

La presente Tesis Doctoral tiene como objetivo el estudio de flujo turbulento cargado con partículas sólidas a través de canales y tuberías de sección constante usando un enfoque Euleriano-Lagrangiano. El campo de flujo de la fase de transporte (aire) se resuelve usando simulación de grandes escalas (LES), implementada en un programa de volúmenes finitos mientras que las ecuaciones gobernantes de la fase dispersa son resueltas por medio de un algoritmo de seguimiento Lagrangiano de partículas que ha sido desarrollado y acoplado al programa que resuelve el flujo. Se estudia de manera sistemática y progresiva la interacción fluido→partícula (one-way coupling), a través de diferentes configuraciones geométricas en coordenadas cartesianas (canales de sección constante y variable) y en coordenadas cilíndricas (tuberías de sección constante y sección variable) abarcando diferentes números de Reynolds y diferentes tamaños de partículas; todos los resultados obtenidos han sido comparados con datos publicados previamente. El estudio de flujo multifásico a través de, tuberías de sección variable, ha sido abordada en otras investigaciones mayoritariamente de forma experimental o mediante simulación usando modelos de turbulencia menos complejos y no mediante LES. El patrón de flujo que se verifica en una tubería con expansión es muy complejo y dicha configuración geométrica se halla en múltiples aplicaciones industriales que involucran el transporte de partículas sólidas, por ello es de gran interés su estudio. Como hecho innovador, en esta tesis no solo se resuelven las estadísticas de velocidad del fluido y las partículas en tuberías con diferentes tamaños de expansión y diferentes regímenes de flujo sino que se caracteriza, usando diversas formulaciones del número de Stokes y el parámetro de arrastre, el ingreso y acumulación de partículas dentro de la zona de recirculación, obteniéndose resultados coincidentes con datos experimentales. ABSTRACT The objective of this Thesis research is to study the turbulent flow laden with solid particles through channels and pipes with using Eulerian-Lagrangian approach. The flow field of the transport phase (air ) is solved using large eddy simulation ( LES ) implemented in a program of finite volume while the governing equations of the dispersed phase are resolved by means of a particle Lagrangian tracking algorithm which was developed and coupled to principal program flow solver . We studied systematically and progressively the fluid interaction → particle ( one- way coupling ) , through different geometric configurations in Cartesian coordinates ( channel with constant and variable section) and in cylindrical coordinates ( pipes with constant section and variable section ) covering different Reynolds numbers and different particle sizes, all results have been compared with previously published data . The study of multiphase flow through, pipes with variable section has been addressed in other investigations predominantly experimentally or by simulation using less complex models and no turbulence by LES. The flow pattern is verified in a pipe expansion is very complex and this geometry is found in many industrial applications involving the transport of solid particles, so it is of great interest to study. As an innovator fact , in this Thesis not only finds fluid velocity statistics and particles with different sizes of pipe expansion and different flow regimes but characterized, using various formulations of the Stokes number and the drag parameter are resolved, the entry and accumulation of particles within the recirculation zone , matching results obtained with experimental data.

The dispersion of solid particles in the turbulent recirculation zones of sudden expansion pipes can be characterized by different Stokes numbers and mean drift parameter and its study is important because this kind of flows appears in many technological applications.

Upprättat; 2013; 20150603 (ninhul)

In this paper the most important constraints of the wind sensors for the Martian atmosphere are described, along with an overview of the past successful designs. Practically all the data available today about the Martian surface wind has been measured using hot film anemometry. A novel wind sensor element is described that will be equipping a REMS (remote environment monitoring system) instrument for the MSL rover by NASA. The device is based on four silicon chips coplanarly assembled, embedded inside an electrothermal sigma-delta closed loop, with digital readout. The device has been shown to be able to work at 6mbar pressure in CO2 atmosphere, and to sense winds up to 60 m/s with a 1 second response time. The design and fabrication of a 2D wind sensor has been developed by the authors, and will be mounted in a full 3D structure by a larger research team involving CRISA and CAB

En el presente trabajo se desarrolla una metodología para llevar a cabo el análisis dinámico de una válvula cardíaca artificial en condiciones de flujo no estacionario, usando un programa de computación de aplicaciones generales basado en el Método de los Volúmenes Finitos. Dicha metodología comprende el establecimiento e implementación computacional de un modelo que representa el movimiento de la válvula (posición, velocidad y aceleración angular) como el resultado de la acción de fuerzas debidas a la presión y a los esfuerzos cortantes del fluido, tomando en cuenta la inercia de la prótesis, así como el establecimiento e imposición como condición de contorno de una función de presión en la entrada del conducto. Con la finalidad de implementar la metodología desarrollada se realiza un estudio preliminar para seleccionar la malla más adecuada, determinar el tamaño óptimo del paso en el tiempo y el mínimo número de iteracciones a utilizar. Posteriormente, se resuelve el flujo laminar, incomprensible y newtoniano a través de una válvula de doble hoja en posición aórtica, y se realiza un estudio paramétrico para analizar la influencia del cambio de diversos párametros inherentes a la prótesis sobre su desempeño.

En este trabajo se presenta la implantación del método SIMPLET en un programa de elementos finitos basados en volúmenes de control. Este método toma en cuanta las variaciones de temperatura en la determinación del campo de presiones en problemas de convección libre, con el próposito de acelerar la convergencia y disminuir los tiempos de computación. El método SIMPLET, que originalmente ha sido propuesto en base al método de diferencias finitas con mallas desplazadas, se implementó en un programa de elementos finitos basados en volúmenes de control con mallas no desplazadas. Se resolvió un problema de convección libre en una cavidad cuadrada y los resultados obtenidos en términos del número de iteracciones y tiempo de computación se compararon se compararon con los resultados del método SIMPLE. Los resultados muestran que en este tipo de problemas el método SIMPLET es más rápido que le SIMPLE cuando el número de Rayleigh es bajo, mientras que para números de Rayleigh elevados, el desempeño de ambos métodos es similar.

Sin resumen