Engineering Commons^™

Validation Of Rhocentralfoam For Engineering Applications Of Under-Expanded Impinging Free Jets, Peter Nielsen

Electronic Thesis and Dissertation Repository

A numerical validation study of under-expanded impinging jet is conducted using OpenFOAM, an open-source computational fluid dynamics (CFD) library. RhoCentralFoam, a density based, compressible flow solver with a two-equation shear stress transport (SST) turbulence model is used on an axisymmetric model to reduce the computation cost. Major features of the flow were compared to an experimental study by Henderson et al., with a nozzle pressure ratio (NPR) of 4.0 and nozzle to plate spacing between 1.65-4.16. Of the features measured, the Mach diamond spacing, super-sonic core, and shear layer are all accurately predicted, while the recirculation bubble in the impingement …

Modal Analysis And Analytical Modeling Of Tornado-Like Vortices, Mohammad Karami

Electronic Thesis and Dissertation Repository

Regardless of the type of vortex chamber, many tornado simulators generate flows that reveal similar flow patterns and a general agreement on the variations of the flow structures with swirl ratio (the ratio of tangential velocity to radial velocity) was achieved. However, very little is known about the underlying physics of the flow, mostly of the fluctuating one, as the previous studies have mainly focused on qualitative flow visualization and the quantitative description of the mean flow.

Herein, coherent structures in tornado-like vortices are extracted using modal decomposition techniques. Modal analysis helps us to better understand the complex vortex dynamics …

Machine Learning Classification Of Interplanetary Coronal Mass Ejections Using Satellite Accelerometers, Kelsey Doerksen

Electronic Thesis and Dissertation Repository

Space weather phenomena is a complex area of research as there are many different variables and signatures that are used to identify the occurrence of solar storms and Interplanetary Coronal Mass Ejections (ICMEs), with inconsistencies between databases and solar storm catalogues. The identification of space weather events is important from a satellite operation point of view, as strong geomagnetic storms can cause orbit perturbations to satellites in low-earth orbit. The Disturbance storm time (Dst) and the Planetary K-index (Kp) are common indices used to identify the occurrence of geomagnetic storms caused by ICMEs, among several other signatures that are not …

Nonlinear Attitude And Pose Filters With Superior Convergence Properties, Hashim Abdellah Hashim Mohamed

Electronic Thesis and Dissertation Repository

In this thesis, several deterministic and stochastic attitude filtering solutions on the special orthogonal group SO(3) are proposed. Firstly, the attitude estimation problem is approached on the basis of nonlinear deterministic filters on SO(3) with guaranteed transient and steady-state measures. The second solution to the attitude estimation problem considers nonlinear stochastic filters on SO(3) with superior convergence properties with two filters being developed in the sense of Ito, and one in the sense of Stratonovich.

This thesis also presents several deterministic and stochastic pose filtering solutions developed on the special Euclidean group SE(3). The first solution includes two nonlinear deterministic …