Unsteady shear layer roll-up modeling

Ιωάννου, Θεόδωρος; Ioannou, Theodoros

dc.contributor.author	Ιωάννου, Θεόδωρος	el
dc.contributor.author	Ioannou, Theodoros	en
dc.date.accessioned	2017-03-08T11:32:25Z
dc.date.available	2017-03-08T11:32:25Z
dc.date.issued	2017-03-08
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/44581
dc.identifier.uri	http://dx.doi.org/10.26240/heal.ntua.6579
dc.description	Εθνικό Μετσόβιο Πολυτεχνείο--Μεταπτυχιακή Εργασία. Διεπιστημονικό-Διατμηματικό Πρόγραμμα Μεταπτυχιακών Σπουδών (Δ.Π.Μ.Σ.) “Υπολογιστική Μηχανική”	el
dc.rights	Αναφορά Δημιουργού-Μη Εμπορική Χρήση-Όχι Παράγωγα Έργα 3.0 Ελλάδα	*
dc.rights.uri	http://creativecommons.org/licenses/by-nc-nd/3.0/gr/	*
dc.subject	Μέθοδος συνοριακών στοιχείων	el
dc.subject	Μέθοδος πλεγματικών δινών	el
dc.subject	Δίνες ακροπτερυγίου	el
dc.subject	Γραμμική θεωρία συνοριακών στοιχείων	el
dc.subject	Υπολογιστική μηχανική	el
dc.subject	Boundary element method	en
dc.subject	Vortex lattice method	en
dc.subject	3-D BEM	en
dc.subject	Vortex roll-up modeling	en
dc.subject	Computational fluid dynamics	en
dc.title	Unsteady shear layer roll-up modeling	en
heal.type	masterThesis
heal.secondaryTitle	Vortex lattice method	en
heal.classification	Computational fluid mechanics	en
heal.classification	CFD analysis	en
heal.classification	Υπολογιστικές μέθοδοι στη ρευστοδυναμική	el
heal.classificationURI	http://data.seab.gr/concepts/e6ab3f6b562030c0c8396c8ff25de47e482748f3
heal.language	en
heal.access	free
heal.recordProvider	ntua	el
heal.publicationDate	2016-10-25
heal.abstract	The Vortex Lattice Method (VLM), is a branch of the well-known Boundary Element Methods (BEM). As all BEM formulations, VLM is based on the Potential theory which has been extensively studied since the early 1900’s [25], [26], [32]. By using all the fundamental theorems of the potential theory, the VLM assumes inviscid and incompressible flows and seeks for solutions on the boundary of the problem. Panel methods for 3-D flow problems start with the pioneering work of Hess and Smith [18] who calculated the flow field velocities and pressures around arbitrarily shaped bodies both for steady and unsteady phenomena. In later years others followed with excellent publications and books such as Basu and Hancock [1], Katz and Plotkin [22] and Jack Moran [24]. The BEM/VLM when applied for 3-D flow problems where viscosity creates free shear layers, result in free boundary problems. This means that part of the domain of definition of our problems is unknown and dynamically evolved. The domain of definition of such problems is the boundary of the body and the shear layer or wake, were the latter is the fluid surfaces that trails the body. Numerous papers and books have been published that discuss the nature of the shear layer and propose a number of modeling techniques for example the book of Malchioro and Pulvirenti [29] and the publication of Morino and Piva [31]. More recent paper publications regarding the shear layer and their modeling can be attributed to G. Politis [38] and Koumoutsakos et al. [26]. By using the VLM instabilities of two kinds appear in the shear layer: a) the Kelvin-Helmholtz instability, b) the roll-up of the free edges of the layer. These instabilities lead to chaotic behavior of the shear layer’s evolution with the passage of time. The above instabilities lead to specialized methods for the wake modeling. The most advanced is the so-called “free” shear layer method, which uses a number of filtering techniques (i.e. introducing viscosity artificially) in order to make such instabilities vanish. Another simpler type of modeling is the “prescribed” wake method. This method uses a frozen wake surface that does not change with time and its shape results only from the motion of the body. Both methods shall be used in this thesis. In the dissertation, we are going to solve the problem of the motion of a wing, as it moves through a flow field. The problem and the equations describing the problem will be formulated for an inertial observer and not for body-fixed observer. This immediately means that Geometric and Motion Preprocessor Programs will be needed for generating the geometry and motion of the wing. The motion of the wing will be a combination of a translational, a heaving and a pitching motion, where also a background velocity field (i.e. sinusoidal gust) will be considered. The wing will be regarded as a flat wing and the method for solving the problem will be the VLM. The wake of the wing will be modeled by the “free wake” method, but the option of modeling the wake with the “prescribed” method will also be available. All results will be compared with the two-dimensional theory, to verify the validity of our method.	en
heal.advisorName	Πολίτης, Γεράσιμος	el
heal.committeeMemberName	Μπελιμπασάκης, Κωνσταντίνος	el
heal.committeeMemberName	Πολίτης, Γεράσιμος	el
heal.committeeMemberName	Ριζιώτης, Βασίλειος	el
heal.academicPublisher	Εθνικό Μετσόβιο Πολυτεχνείο. Σχολή Χημικών Μηχανικών	el
heal.academicPublisherID	ntua
heal.numberOfPages	98 σ.	el
heal.fullTextAvailability	true