Analysis of the forces driving the oscillations in 3D fluidic oscillators

One of the main advantages of fluidic oscillators is that they do not have moving parts, which brings high reliability whenever being used in real applications. To use these devices in real applications, it is necessary to evaluate their performance, since each application requires a particular injected fluid momentum and frequency. In this paper, the performance of a given fluidic oscillator is evaluated at different Reynolds numbers via a 3D-computational fluid dynamics (CFD) analysis. The net momentum applied to the incoming jet is compared with the dynamic maximum stagnation pressure in the mixing chamber, to the dynamic output mass flow, to the dynamic feedback channels mass flow, to the pressure acting to both feedback channels outlets, and to the mixing chamber inlet jet oscillation angle. A perfect correlation between these parameters is obtained, therefore indicating the oscillation is triggered by the pressure momentum term applied to the jet at the feedback channels outlets. The paper proves that the stagnation pressure fluctuations appearing at the mixing chamber inclined walls are responsible for the pressure momentum term acting at the feedback channels outlets. Until now it was thought that the oscillations were driven by the mass flow flowing along the feedback channels, however in this paper it is proved that the oscillations are pressure driven. The peak to peak stagnation pressure fluctuations increase with increasing Reynolds number, and so does the pressure momentum term acting onto the mixing chamber inlet incoming jetPostprint (published version

A 8-neighbor model lattice Boltzmann method applied to mathematical-physical equations

© 2016. This version is made available under the CC-BY-NC-ND 4.0 license http://creativecommons.org/licenses/by-nc-nd/4.0/A lattice Boltzmann method (LBM) 9-bit model is presented to solve mathematical-physical equations, such as, Laplace equation, Poisson equation, Wave equation and Burgers equation. The 9-bit model has been verified by several test cases. Numerical simulations, including 1D and 2D cases, of each problem are shown respectively. Comparisons are made between numerical predictions and analytic solutions or available numerical results from previous researchers. It turned out that the 9-bit model is computationally effective and accurate for all different mathematical-physical equations studied. The main benefits of the new model proposed is that it is faster than the previous existing models and has a better accuracy.Peer ReviewedPostprint (author's final draft

Numerical study of the 2D lid-driven triangular cavities based on the Lattice Boltzmann method

Numerical study of two dimensional lid driven triangular cavity flow is performed via using lattice Boltzmann method on low Reynolds numbers. The equilateral triangular cavity is the first geometry to be studied, the simulation is performed at Reynolds number 500 and the numerical prediction is compared with previous work done by other scholars. Several isosceles triangular cavities are studied at different initial conditions, Reynolds numbers ranging from 100 to 3000, regardless of the geometry studied, the top lid is always moving from left to right and the driven velocity remains constant. Results are also compared with previous work performed by other scholars, the agreement is very good. According to the authors’ knowledge, this is the first time that MRT-LBM model is used to simulate the flow inside the triangular cavities. One of the advantages of this method is that it is capable of producing at low and high Reynolds numbers.Peer ReviewedPostprint (published version

Mecánica de fluidos : problemas resueltos

Descripció del recurs: 21 de setembre de 2011El presente libro es fruto de la experiencia adquirida durante toda una carrera universitaria. Muchos de los problemas que en él se exponen fueron, en su momento, problemas de examen de la asignatura Mecánica de Fluidos. Por una parte, esta obra está diseñada para presentar, de manera sencilla, diversos temas básicos de la mecánica de fluidos que todo estudiante de la asignatura debe conocer. Asimismo, pretende ser un libro de repaso para quienes, habiendo estudiado Ingeniería y trabajando en la industria, necesiten fijar determinados conceptos sobre la materia. Finalmente, esta obra también quiere servir de apoyo a todas las escuelas de los países de habla hispana que imparten las diversas ingenierías, y ser un instrumento útil de repaso de la temática presentada

Mecánica de fluidos : breve introducción teórica con problemas resueltos

Descripció del recurs: 13 de maig de 2015El presente libro es fruto de la experiencia adquirida durante toda una carrera universitaria. Esta obra está diseñada para presentar los principios básicos de la Mecánica de Fluidos de una manera clara y muy sencilla, muchos de los problemas que se exponen fueron, en su momento, problemas de examen de la asignatura. Asimismo, pretende ser un libro de repaso para quienes, habiendo estudiado Ingeniería y trabajando en la industria, precisan fijar determinados conceptos sobre la materia. Finalmente, se desea que esta obra sirva de apoyo a todas las escuelas de los países de habla hispana que imparten las diversas Ingenierías. Espero y deseo que este libro sea un instrumento útil de introducción de la temática presentada.2a ed

Mecánica de fluidos : problemas resueltos

Descripció del recurs: 9 de juny de 2017El presente libro es fruto de la experiencia adquirida durante toda una carrera universitaria. Muchos de los problemas que se exponen fueron, en su momento, problemas de examen de la asignatura Mecánica de Fluidos. Por una parte, esta obra cubre y se dedica a presentar, de manera sencilla, diversos temas básicos de la mecánica de fluidos, que todo estudiante de la asignatura debe conocer. Asimismo, pretende ser un libro de repaso para quienes, habiendo estudiado Ingeniería y trabajando en la industria, precisan fijar determinados conceptos sobre la materia. Finalmente, se desea que esta obra sirva de apoyo a todas las escuelas de los países de habla hispana que imparten las diversas ingenierías, y que sea un instrumento útil de repaso de la temática presentada.Segunda edició

Aerodynamic study of the NASA’s X-43A hypersonic aircraft

A two-dimensional aerodynamic study of the NASA’s X-43A hypersonic aircraft is developed using two different approaches. The first one is analytical and based on the resolution of the oblique shock wave and Prandtl–Meyer expansion wave theories supported by an in-house program and considering a simplified aircraft’s design. The second approach involves the use of a Computational Fluid Dynamics (CFD) package, OpenFOAM and the real shape of the aircraft. The aerodynamic characteristics defined as the lift and drag coefficients, the aerodynamic efficiency and the pitching moment coefficient are calculated for different angles of attack. Evaluations are made for an incident Mach number of 7 and an altitude of 30 km. The CFD approach has been extended to a full threedimensional model in order to be compared with the 2D modelPostprint (published version

Aerodynamic efficiency improvement on a NACA-8412 airfoil via active flow control implementation

The present paper introduces a parametric optimization of several Active Flow Control (AFC) parameters applied to a NACA-8412 airfoil at a single post-stall Angle of Attack (AoA) of 15° and Reynolds number Re = 68.5×103. The aim is to enhance the airfoil efficiency and to maximize its lift. The boundary layer separation point was modified using Synthetic Jet Actuators (SJA), and the airfoil optimization was carried on by systematically changing the pulsating frequency, momentum coefficient and jet inclination angle. Each case has been evaluated using Computational Fluid Dynamic (CFD) simulations, being the Reynolds Averaged Navier–Stokes equations (RANS) turbulence model employed the Spalart Allmaras (SA) one. The results clarify which are the optimum AFC parameters to maximize the airfoil efficiency. It also clarifies which improvement in efficiency is to be expected under the operating working conditions. An energy balance is presented at the end of the paper, showing that for the optimum conditions studied the energy saved is higher than the one needed for the actuation. The paper clarifies how a parametric analysis has to be performed and which AFC parameters can be initially set as constant providing sufficient previous knowledge of the flow field is already known. A maximum efficiency increase versus the baseline case of around 275% is obtained from the present simulationsPostprint (published version

Mecánica de fluidos : breve introducción teórica con problemas resueltos

Descripció del recurs: 14 de desembre de 2012El presente libro es fruto de la experiencia adquirida durante toda una carrera universitaria. Esta obra está diseñada para presentar los principios básicos de la Mecánica de Fluidos de una manera clara y muy sencilla, muchos de los problemas que se exponen fueron, en su momento, problemas de examen de la asignatura. Asimismo, pretende ser un libro de repaso para quienes, habiendo estudiado Ingeniería y trabajando en la industria, precisan fijar determinados conceptos sobre la materia. Finalmente, se desea que esta obra sirva de apoyo a todas las escuelas de los países de habla hispana que imparten las diversas Ingenierías. Espero y deseo que este libro sea un instrumento útil de introducción de la temática presentada

Mecánica de fluidos : breve introducción teórica con problemas resueltos

Descripció del recurs: 27 de novembre de 2017El presente libro es fruto de la experiencia adquirida durante toda una carrera universitaria. Esta obra está diseñada para presentar los principios básicos de la Mecánica de Fluidos de una manera clara y muy sencilla. Muchos de los problemas que se exponen fueron, en su momento, problemas de examen de la asignatura. Asimismo, pretende ser un libro de repaso para quienes, precisen fijar determinados conceptos sobre la materia. Finalmente, se desea que esta obra sirva de apoyo a todas las escuelas de los países de habla hispana que imparten las diversas Ingenierías. Espero y deseo que este libro sea un instrumento útil de repaso de la temática presentada.3a edició