Item – Theses Canada

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OCLC number
1132143143
Link(s) to full text
LAC copy
Author
Amiri, Amin,
Title
Buoyant miscible displacement flows of Newtonian and non-Newtonian fluids : stationary and oscillating geometries
Degree
Philosophiæ doctor (Ph. D.) -- Université Laval, 2019
Publisher
Québec : Université Laval, 2019
Description
1 ressource en ligne (xxvi, 131 pages) :illustrations en couleur, graphiques, fichier PDF (27,4 Mo)
Notes
Titre de l'écran-titre (visionné le 15 octobre 2019).
Thèse ou mémoire avec insertion d'articles.
Bibliographie : pages 119-129.
Abstract
This thesis aims to investigate buoyant displacement flows of miscible fluids in a long, vertical stationary pipe or a moving pipe. For the case of the moving geometry, the pipe oscillates like an inverted pendulum with a small maximum frequency, i.e.ˆf= 0.2(Hz) and a small maximum oscillation amplitude, i.e. 15 (⁰) with respect to the pipe axis. The displacement flows occur at the high Péclet number and small Atwood numbers. The focus is on the type of fluids and geometries (stationary or moving pipe). Detailed experimental approaches are employed in an integrated fashion. The density configuration in this thesis is the density unstable. The main part of the current work is concentrated on displacement flows of iso-viscous Newtonian fluids. We also study the yield stress displacement flow in a long vertical pipe. For iso-viscous Newtonian displacement flow in a stationary pipe, we uncover the stabilizing effect of the mean imposed flow and report the existence of two main flow regimes at long times introduced as a stable displacement flow and an unstable displacement flow. The transition between these two regimes occurs at a critical modified Reynolds number (Ret-Critical), as a function of Froude number (Fr). We investigate deeply the stable flow regime : first, a lubrication model combined with a simple initial acceleration formulation suggests a predictionof the time-dependent penetrating displacing front velocity. Second, we find two sub-regimes for the stable displacement flow, namely sustained-back-flows and no-sustained-back-flows. The transition between the two sub-regimes is a marginal stationary interface flow state, which is also well predicted by the lubrication model. For the iso-viscous Newtonian displacement flow in the moving pipe, three different flow regimes are introduced : a stable flow that is non-diffusive (atRe/Ro <70&Ret/Fr <35), a stable-diffusive flow (atRe/Ro>70&Ret/Fr <35) and an unstable-diffusive flow (atRet/Fr>35) whereRe, Retand Rorepresent the Reynolds number, the modified Reynolds number, and the Rossby number, respectively. In addition, penetrating front velocities as wellas macroscopic diffusion coefficients are measured. The results indicate that depending on thevalue of the density difference and the mean imposed flow velocity, the geometrical movements can have different and even opposite effects, e.g. slightly increase or decrease the front velocity. The pipe motion seems to also slightly increase the macroscopic diffusion coefficient.
Other link(s)
Accès via CorpusUL
Subject
Fluid dynamics.
Pipe.
Dynamique des fluides.
Tuyaux.
Dynamique des fluides
Tuyaux