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The Paper revolves around the question of fluid flow. The flow is being analyzed by the 8- Theory Framework and Not on Vector space. than we can see exactly why fluid motion is chaotic.&nbsp

Most computational fluid dynamics simulations are, at present, performed in a body-fixed frame, for aeronautical purposes. With the advent of sharp manoeuvre, which may lead to transient effects originating in the acceleration of the centre of mass, there is a need to have a consistent formulation of the Navier–Stokes equations in an arbitrarily moving frame. These expressions should be in a form that allows terms to be transformed between non-inertial and inertial frames and includes gravity, viscous terms, and linear and angular acceleration. Since no effects of body acceleration appear in the inertial frame Navier–Stokes equations themselves, but only in their boundary conditions, it is useful to investigate acceleration source terms in the non-inertial frame. In this paper, a derivation of the energy equation is provided in addition to the continuity and momentum equations previously published. Relevant dimensionless constants are derived which can be used to obtain an indication of the relative significance of acceleration effects. The necessity for using computational fluid dynamics to capture nonlinear effects remains, and various implementation schemes for accelerating bodies are discussed. This theoretical treatment is intended to provide a foundation for interpretation of aerodynamic effects observed in manoeuvre, particularly for accelerating missiles. Funding agencies: DRDB [KT466921, KT528944, KT470887]

INTRODUCTION Shoreface-connected sand ridges (SCSR) are accumulations of sand that occur in the inner shelfs of the world at spatial scales of a few kilometers and temporal scales of centuries. Sometimes, several ridges appear attached to the coast and extending seaward with an oblique orientation, the alongshore distance between the different bars being remarkably constant (see examples in figures 2 and 18 of the attached article). These features are relevant for engineering applications, biology and geology. The formation of such alongshore-rhythmic ridges can be due to The large amount of sand provided by coastal erosion in the river mouth and the combination between high-speed currents induced by Mistral wind and severe wave-storm events might have been the favourable conditions in the Ebro delta for the formation of structures that can be considered the initial stages of shoreface-connected sand ridges development. This type of dynamic submerged structures are elongated sand bed forms that evolve during storms when high waves and intense storm-driven currents erode and transport sediment by exerting shear stresses at the sandy seabed. The morphological characteristics of these sand ridges are investigated for the case of the Ebro delta with two adapted codes called Morfo25 and Morfo62, based on linear stability analysis, and designed to describe inner shelf and surf zone morphodynamics, respectively. The hydrodynamic and geomorphological conditions of the Delta are applied on both models and the modelled results are analyzed and compared with the obtained data in the Ebro delta. Model results presents shoreface-connected sand ridges with morphological characteristics similar to those of the Ebro Delta, thereby confirming the hypothesis. It is proved that these ridges requires of strong NW wind and E-SE storm events at the same time. Furthermore, an improved description of wave processes does not have any effect on their characteristics because waves are shore-normal. La gran cantidad de arena proporcionada por la erosión costera en la desembocadura del río y la combinación de fuertes corrientes inducidas por viento Mistral y olas generadas por las tormentas podrían haber sido las condiciones favorables en el delta del Ebro para la formación de estructuras que pueden considerarse las etapas iniciales del desarrollo de crestas de arena en la placa continental (shoreface-connected sand ridges). Este tipo de estructuras sumergidas dinámicas son crestas de arena alargadas que evolucionan durante las tormentas cuando las altas olas y las intensas corrientes erosionan y transportan los sedimentos ejerciendo tensiones de corte en el lecho marino. Las características de estas crestas se investigan para el caso del delta del Ebro con dos códigos adaptados, Morfo25 y Morfo62, basados en el análisis de estabilidad lineal, y diseñado para describir los procesos morfodinámicos de la plataforma continental y de la zona de oleaje, respectivamente. Las condiciones hidrodinámicas y geomorfológicas del Delta se aplican en ambos modelos y los resultados modelados se analizan y comparan con los datos obtenidos en el delta del Ebro. Los resultados de los modelos presentan shoreface-connected sand ridges con características similares a éstas del delta del Ebro, confirmando así la hipótesis. Es demostrado que estas crestas requieren de fuerte viento NO y tormentas del E-SE al mismo tiempo. Además, una mejor descripción de los procesos del oleaje no tienen ningún efecto en sus características porque las olas son perpendicular a la orilla. La gran quantitat de sorra proporcionada per l'erosió costanera a la desembocadura del riu i la combinació entre els forts corrents induïts pel vent de Mistral i les onades generades per tempestes podrien haver estat les condicions favorables del delta de l'Ebre per a la formació d'estructures que es poden considerar les etapes inicials del desenvolupament de les crestes de sorra a la placa continental (shoreface-connected sand ridges). Aquest tipus d'estructures submergides dinàmiques són crestes allargades que evolucionen durant les tempestes, quan les ones altes i els corrents intensos de la tempesta erosionen i transporten sediments exercint tensions al fons de fons de sorra. Les característiques s'investiguen pel cas del delta de l'Ebre amb dos codis adaptats, Morfo25 i Morfo62, basat en l'anàlisi d'estabilitat lineal, i dissenyat per a descriure els processos morfodinàmics de la plataforma continental i de la zona de surf, respectivament. Les condicions hidrodinàmiques i geomorfològiques del Delta s'apliquen en ambdós models i s'analitzen els resultats modelats i es comparen amb les dades obtingudes en el delta de l'Ebre. Els resultats dels models presenten shoreface-connected sand ridges amb característiques similars a aquestes del delta de l'Ebre, confirmant així la hipòtesi. És demostrat que aquestes crestes requereixen de fort vent NO i tempestes de l'E-SE al mateix temps. A més, una millor descripció dels processos de l'onatge no tenen cap efecte en les seves característiques perquè les onades són perpendicular a la riba.

An Inertial Particle Separator (IPS) is a particulate removal device typically installed at the inlet of a gas turbine to mitigate effects of sand ingestion on the engine. This system can minimize particulate ingestion during helicopter landings in austere brown-out conditions so as to increase engine life. Typically, IPS systems have lower engine power losses than alternative engine inlet filtration technologies. The present studies investigated a variety of novel IPS geometries. Tests were conducted on a fundamental two-dimensional experimental facility that allows optical access. Geometries were evaluated using a variety of performance criteria. Of primary import is particle separation efficiency which measures the effectiveness of the system at removing particulate from the core engine flow stream. The separation efficiency of a particular IPS configuration is reliant in part on the characteristics of the flowfield, especially for finer particulate. Low scavenge air mass flow fractions are desirable, as it is directly related to the amount of power diverted from the engine to power the IPS. However, lowering scavenge mass flow fraction increases rates of flow separation and instability, leading to lost particle separation efficiency. There is a lack of available experimental data for IPS geometries designed to operate effectively at these low scavenge mass flow fractions. Modifications from a baseline geometry were made to the scavenge leg and Outer Surface Geometry (OSG). Performance was evaluated based on particle separation efficiency, Particle Image Velocimetry (PIV), surface flow visualization, first order predictive methods, as well as power loss and mass flow rate variations. These experiments showed that reductions in the scavenge channel height were effective at increasing separation efficiency at low scavenge mass flow fraction. Additionally, these modifications successfully reduced flow instability and demonstrated a link between flow separation and particle separation efficiency. The present studies provide comprehensive empirical data to guide future development of IPS geometries specifically optimized to perform effectively at low power levels.

espanolEste trabajo presenta una propuesta didactica constructivista, basada en la realizacion de laboratorios experimentales para la unidad de fisica de fluidos, que fue disenada por estudiantes de pedagogia en fisica de la Universidad de Concepcion, Chile. La metodologia consta de tres etapas: i) teorico- conceptual; ii) experimental y obtencion de resultados y iii) analisis de la informacion y resultados. La propuesta fue implementada, ejecutada y probada en cursos de nivel secundario de un colegio local. Segun el factor de Hake, los resultados muestran que los estudiantes obtuvieron una alta ganancia conceptual de aprendizajes observada en el incremento de las calificaciones. Mas aun, se observo un cambio en la dinamica de trabajo de los estudiantes, lo que fue verificado por el incremento de la afinidad y la transferencia de aprendizajes en el grupo. La formulacion de propuestas didacticas constructivista bajo la metodologia experimental muestra ser relevante en el proceso de ensenanza-aprendizaje para la formacion universitaria de futuros docentes de ciencias. EnglishThis paper presents a constructivist didactic proposal, based on the performance of experimental laboratories of fluid physics unit, designed by students of bachelor of education in natural and physical sciences at the University of Concepcion, Chile. The methodology consists of three steps: i) theoretical and conceptual; ii) experimental and data gathering; and iii) data analysis and results. The proposal was implemented, executed and tested in high school courses at a local college. Hake factor indicates that students had high conceptual learning gain, observed in the increase in average scores. Furthermore, a change was observed in the workflow of students, verified by the increased affinity in the group, as well as by the appearance of a learning transfer network. The formulation of didactic constructivist proposals under experimental methodology proves to be relevant in the teaching-learning process of future science teachers.

Life in the ocean is shaped by the trade-off between a need to encounter other organisms for feeding or mating, and to avoid encounters with predators. Avoiding or achieving encounters necessitates an efficient means of collecting the maximum possible information from the surroundings through the use of remote sensing. In this study, we explore how sensing mode and range depend on body size. We reveal a hierarchy of sensing modes (chemosensing, mechanosensing, vision, hearing, and echolocation) where body size determines the available battery of sensing modes and where larger body size means a longer sensing range. The size-dependent hierarchy and the transitions between primary sensory modes are explained on the grounds of limiting factors set by physiology and the physical laws governing signal generation, transmission and reception. We characterize the governing mechanisms and theoretically predict the body size limits for various sensory modes, which align very well with size ranges found in literature. The treatise of all ocean life, from unicellular organisms to whales, demonstrates how body size determines available sensing modes, and thereby acts as a major structuring factor of aquatic life.

The turbulen flow in an asymmetric diffuser has been en studied by the means of Reynold average Navier-Stokes equations with both differential and explict algebraic expressions to model the Reynolds stress tensor. Modifications to the differential stress model have been derived, using the inverse turbulence timescale to obtain the dissipation of turbuence kinetic energy. The explicit algebraic Reynolds stress model has been used in combination with a two-equation platform to close the system of equations. Modifications made to the transport equation for the inverse turbulence timescale has made it possible to substantially relax the deman on near-wall resolution of this quantity. The rapid growth wth present in the original formulation can be treated as an explicit function of the wall-normal distance. In order to use the new formulation for the transport equation, an equation has as been derived to obtain the shortest distance bettwee a point and the closest wall, regardles of the geometric complexity of the domain. An explicit algebraic expression to model the passive scalar flux vector has been investigated using a comparison with a standard eddy-diffusivity model in the asymmetric diffuser. Results show a substantial improvement of the complexity of the scalar field and scalar flux vector in sepaarated flows. Automated code generation has been used in all the above studies to generate versatile model testing tools for general two-dimensional geometries. Finite element formulations are used for these tools.