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The main focus of this work is to investigate experimentally the transition to turbulence of a yield stress shear thinning fluid in Hagen-Poiseuille flow. By combining direct high speed imaging of the flow structures with Laser Doppler Velocimetry (LDV), we provide a systematic description of the different flow regimes from laminar to fully turbulent. Each flow regime is characterized by measurements of the radial velocity, velocity fluctuations, and turbulence intensity profiles. In addition we estimate the autocorrelation, the probability distribution, and the structure functions in an attempt to further characterize transition. For all cases tested, our results indicate that transition occurs only when the Reynolds stresses of the flow equals or exceeds the yield stress of the fluid, i.e. the plug is broken before transition commences. Once in transition and when turbulent, the behavior of the yield stress fluid is somewhat similar to a (simpler) shear thinning fluid. We have also observed the shape of slugs during transition and find that their leading edges to be highly elongated and located off the central axis of the pipe, for the non-Newtonian fluids examined. Finally we present a new phenomenological approach for quantifying laminar-turbulent transition in pipe flow. This criterion is based on averaging a local Reynolds number to give ReG. Our localised parameter shows strong radial variations that are maximal at approximately the radial positions where puffs first appear during the first stages of turbulent transition.

Thesis (M. Sc.)--University of Alberta, 2009. / Title from pdf file main screen (viewed on Dec. 10, 2009). "A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science in Chemical Engineering, [Department of] Chemical and Materials Engineering, University of Alberta." Includes bibliographical references.

This research deals with several novel aspects of finite element formulations and methodology in parallel adaptive simulation of flow problems. Composite macroelement schemes are developed for problems of thin fluid layers with deforming free surfaces or decomposing material phases; experiments are also run on divergence-free formulations that can be derived from the same element classes. The constrained composite nature and C¹ continuity requirements of these elements raises new issues, especially with respect to adaptive refinement patterns and the treatment of hanging node constraints, which are more complex than encountered with standard element types. This work combines such complex elements with these applications and with parallel adaptive mesh refinement and coarsening (AMR/C) techniques for the first time. The use of adaptive macroelement spaces also requires appropriate programming interfaces and data structures to enable easy and efficient implementation in parallel software. The algorithms developed for this work are implemented using object-oriented designs described herein. One application class of interest concerns heated viscous thin fluid layers that have a deformable free surface. These problems occur in both normal scale laboratory and industrial applications and in micro-fluidics. Modeling this flow via depth averaging gives a nonlinear boundary value problem describing the transient evolution of the film thickness. The model is dominated by surface tension effects which are described by a combination of nonlinear second and fourth-order operators. This research work also includes studies using the divergence-free forms constructed from these elements for certain classes of non-Newtonian fluids such as the Powell-Eyring and Williamson shear-thinning viscosity models. In addition to the target problems we conduct verification studies in support of the simulation development. In the final application investigated, C¹ elements are used in conforming finite element approximations of the Cahn-Hilliard phase field model for moving interface and phase separation problems. The nonlinear Cahn-Hilliard equation combines anti-diffusive configurational free energy based terms with a fourth-order interfacial free energy based term. Numerical studies include both manufactured and physically significant problems, including parametric studies of directed pattern self-assembly in phase decomposition of thin films. The main new contributions include construction of C¹ and div-free macroelement classes suitable for AMR/C with nonconforming hanging node meshes; a posteriori error estimation for fourth-order problems using these and other element classes; use of projection operators to automate the correct treatment of constraints at hanging nodes and through AMR/C steps; design of supporting data structures and algorithms for implementation in a parallel object oriented framework; variational formulations, methodology and numerical experiments with nonlinear fourth-order flow and transport models; and parametric and Monte Carlo studies of directed phase decomposition. / text

Heat transfer to canned particulate laden Newtonian fluids was studied during free axial agitation thermal processing in a pilot STOCK retort which was modified to simulate the can motion in continuous turbo cookers. Evaluation of heat transfer coefficients (overall, U and fluid to particle, hfp) associated with canned liquid/particle mixtures, while they are subjected to free axial motion is difficult because of the problems involved with attaching temperature measuring devices to liquid and particles without affecting their normal motion. A new methodology was developed to evaluate U and hfp in Newtonian liquids. The methodology involved first correlating U and hfp as a function of input variables for cans in fixed axial mode of rotation in which both particle and fluid temperatures were measured using thin wire thermocouples. Subsequently, only liquid temperatures were measured in cans using wireless sensors in the free axial mode, and hfp values were empirically computed from the developed correlations and the measured temperatures. An L-16 orthogonal experimental design of experiment was carried out to select system and product parameters that significantly influence hfp and U for particles in the Newtonian liquid. With significant parameters selected, a response surface methodology and two full factorial experimental designs were used to relate U and hfp to process variables in each mode of rotation (fixed and free axial modes). / Dimensionless correlations were then developed using the evaluated data for heat transfer coefficients (U and hfp), in canned high viscosity Newtonian liquids (with and without particles) using stepwise multiple non-linear-regressions of significant dimensionless groups. In free axial mode, combining the natural and forced convection, Nu = A 1(GrxPr)A2+ A3(Re) A4 (Pr)A5 FrA 6 (rhop/rhop1)A 7 (e/100-e)A8 (dp/Dc) A9 (Kp/K1)A10 yielded a higher R2 (0.93) than using a pure forced convection model when particles were present in the can. Even in the absence of particles, and with the end-over-end mode of agitation where forced convection dominates, introducing natural convection term (GrxPr), improvedR2 from 0.81 to 0.97. Artificial neural network (ANN) models were also developed for heat transfer coefficient predictions and the trained models gave better predictions than dimensionless correlations. All ANN models developed could be implemented easily in a spreadsheet as either matrices or a set of equations.

The main focus of this work is to investigate experimentally the transition to turbulence of a yield stress shear thinning fluid in Hagen-Poiseuille flow. By combining direct high speed imaging of the flow structures with Laser Doppler Velocimetry (LDV), we provide a systematic description of the different flow regimes from laminar to fully turbulent. Each flow regime is characterized by measurements of the radial velocity, velocity fluctuations, and turbulence intensity profiles. In addition we estimate the autocorrelation, the probability distribution, and the structure functions in an attempt to further characterize transition. For all cases tested, our results indicate that transition occurs only when the Reynolds stresses of the flow equals or exceeds the yield stress of the fluid, i.e. the plug is broken before transition commences. Once in transition and when turbulent, the behavior of the yield stress fluid is somewhat similar to a (simpler) shear thinning fluid. We have also observed the shape of slugs during transition and find that their leading edges to be highly elongated and located off the central axis of the pipe, for the non-Newtonian fluids examined. Finally we present a new phenomenological approach for quantifying laminar-turbulent transition in pipe flow. This criterion is based on averaging a local Reynolds number to give ReG. Our localised parameter shows strong radial variations that are maximal at approximately the radial positions where puffs first appear during the first stages of turbulent transition.

Includes bibliographical references (leaves 168-179). / xiii, 179 leaves ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Finds that the post-Newtonian approximation seems to be a better approximation of the general relativistic theory than the standard Newtonian theory. / Thesis (Ph.D.)--Adelaide University, Dept. of Physics and Mathematical Physics, 2001

Thesis (Ph.D)--University of Tulsa, 1987. / Bibliography: leaves 99-104.

Thesis (Ph. D.)--University of Texas at Austin, 2008. / Vita. Includes bibliographical references.

Thesis (Ph.D)--Biomedical Engineering, Georgia Institute of Technology, 2009. / Committee Chair: Yoganathan, Ajit; Committee Member: Fogel, Mark; Committee Member: Kanter, Kirk; Committee Member: Oshinski, John; Committee Member: Skrinjar, Oskar. Part of the SMARTech Electronic Thesis and Dissertation Collection.