Υπολογισμών τριβών σε μικροκανάλια με διφασικές ροές

Λαποκωνσταντάκη, Καλλιόπη; Lapokonstantaki, Kalliopi

dc.contributor.author	Λαποκωνσταντάκη, Καλλιόπη	el
dc.contributor.author	Lapokonstantaki, Kalliopi	el
dc.date.accessioned	2017-06-12T10:16:11Z
dc.date.available	2017-06-12T10:16:11Z
dc.date.issued	2017-06-12
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/45030
dc.identifier.uri	http://dx.doi.org/10.26240/heal.ntua.7243
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	Διφασική ροή	el
dc.subject	Πορώδες μικροκανάλι	el
dc.subject	Απώλειες ενέργειας	el
dc.subject	Παροχή αέρα	el
dc.subject	Γεωμετρία φυσαλίδας	el
dc.subject	Ttwo-phase flow	en
dc.subject	Porous microchannel	en
dc.subject	Viscous Dissipation	en
dc.subject	Air flow	en
dc.subject	Bubbles geometry	en
dc.title	Υπολογισμών τριβών σε μικροκανάλια με διφασικές ροές	el
heal.type	masterThesis
heal.classification	ΥΠΟΛΟΓΙΣΤΙΚΗ ΜΗΧΑΝΙΚΗ	el
heal.access	free
heal.recordProvider	ntua	el
heal.publicationDate	2017-02-17
heal.abstract	In recent years, the multiphase flow in micro-channels has been of particular interest due to numerous applications. In the case of concern in this thesis, external pressure is applied to the porous surfaces of micro-channels, introducing air in the form of micro-bubbles that attach to the internal walls. The micro-bubbles interact with the flowing liquid by either forming a slippery boundary layer that reduces friction or by forming a layer of obstacles that impedes flow and introduces additional friction. The type of interaction depends on the size of the micro-bubbles (large micro-bubbles – high friction, etc.) and the rate of detachment from the porous walls. Detachment occurs due to application of excessive external pressure that causes uncontrolled bubble growth or possibly due to shear stresses from the flowing liquid. The effect of the bubble detachment to the friction losses is investigated with a 3D two-phase model of a micro-channel that is implemented in ANSYS-FLUENT. It is shown that there is a small but effective operating regime in which the friction losses are reduced. For the current case the detachment rate, which is quantifiable in terms of the permeating air flow rate, is in the neighborhood of 0.00311 μl / s. The computational investigation of the effect of bubble size is focused on a single bubble in a unit cell with a model implemented in COMSOL Multiphysics. It is shown that the optimal “bubbly” boundary layer should be quite dense (pores in very close proximity) and the bubbles should have contact angles at ~13.5°-18°, where the more precise value depends on the geometry of the pore; two cases are investigated: pores shaped like narrow slits (translational symmetry, 2D) and pores with circular cross-section (3D).	en
heal.advisorName	Μπουντουβής, Ανδρέας	el
heal.committeeMemberName	Μπουντουβής, Ανδρέας	el
heal.committeeMemberName	Τσουκιάς, Νικόλαος	el
heal.committeeMemberName	Ριζιώτης, Βασίλειος	el
heal.academicPublisher	Εθνικό Μετσόβιο Πολυτεχνείο. Σχολή Χημικών Μηχανικών	el
heal.academicPublisherID	ntua
heal.fullTextAvailability	true