Nonlinearity in the Navier-Stokes equations can originate from a variety of sources, such as contributions stemming from the advective term, constitutive closure models or external factors such as chemical reactions and capillarity. Needless to say, a combination of any of the above sources has the potential to exasperate the problem significantly. This dissertation explores cases that predominantly feature advective and/or capillary effects. In particular, we first consider the inertia-dominated problem of single-phase flow past a confined square cylinder, followed by a study focused on the low-Re dynamics of rigid particles straddling non-planar interfaces.
The first part of the thesis investigates transient, three-dimensional, incompressible and isothermal flow of a Newtonian fluid past a symmetrically confined obstacle at zero incidence. Results from both Laser Doppler Velocimetry (LDV) experiments and direct simulations upto Re = 250 have been reported. Beyond the onset of instability (Recr ≈ 58), an inflexion point around Re ≈ 115 is detected for the Strouhal number with no evidence of hysteresis in any of the measurements. Furthermore, incommensurate frequencies observed in the range 127 ≤ Re ≤ 175 suggest a quasi-periodic transition to three-dimensionality. This is shown to be followed by an intermediate periodic window starting around Re ≈ 180. Fourier analysis and spanwise velocity correlations are then used to characterize the observed phenomena. Subsequent analysis of consolidated data suggest that only a parametric variation of transverse and spanwise blockage ratios can bring closure to the subject of bluff-body wake transitions.
The second part of the thesis implements and validates a physically consistent continuum model for the Moving Contact Line (MCL) through direct simulations. After elaborately discussing the MCL conundrum, a fundamental framework for the simulations is outlined in a theoretical orientation which combines the Level set method with a Fictitious domain approach in a finite-element scheme. The thesis objectives are then realized through simulation of various case studies that show favorable comparisons with theoretical and/or published experimental data. In short, the current work successfully illustrates the potential of novel boundary conditions (such as the GNBC) to accurately describe MCL dynamics. / Chemical Engineering
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:AEU.10048/1941 |
| Date | 11 1900 |
| Creators | Madhavan, Srinath |
| Contributors | Nandakumar, K. (Chemical and Materials Engineering), Minev, P. D. (Mathematical and Statistical Sciences), Hayes, R. E. (Chemical and Materials Engineering), Derksen, J. (Chemical and Materials Engineering), Yeung, A. (Chemical and Materials Engineering), Hu, H. (Mechanical Engineering and Applied Mechanics, University of Pennsylvania) |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | en_US |
| Detected Language | English |
| Type | Thesis |
| Format | 12598861 bytes, application/pdf |
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