Now showing items 29-48 of 50

    • Order in Oscillatory Shear Flow  

      Kanso, Mona A.; Giacomin, A. Jeffrey; Saengow, Chaimongkol; Gilbert, Peter H. (2018-12)
      We examine the second order orientation tensor for the simplest molecular model relevant to a polymeric liquid in large-amplitude oscillatory shear flow (LAOS), the rigid dumbbell suspension. For this we use an approximate ...
    • Orientation Distribution Function Pattern for Rigid Dumbell Suspensions In Any Simply Shear Flow 

      Jbara, Layal; Giacomin, A. Jeffrey (2018-09)
      For rigid dumbbells suspended in a Newtonian solvent, the viscoelastic response depends exclusively on the dynamics of dumbbell orientation. The orientation distribution function ψ (θ ,φ ,t) represents the probability of ...
    • Orientation in Large-Amplitude Oscillatory Shear 

      Schmalzer, Andrew M.; Giacomin, A. Jeffrey (2014-09-30)
      We examine the simplest relevant molecular model for large-amplitude oscillatory shear flow of a polymeric liquid: the dilute suspension of rigid dumbbells in a Newtonian solvent. We find explicit analytical expressions ...
    • Padé Approximant for Normal Stress Differences in Large-Amplitude Oscillatory Shear Flow 

      Poungthong, P.; Saengow, Chaimongkol; Giacomin, A. Jeffrey; Kolitawong, Chanyut; Merger, D.; Wilhelm, M. (2017-11)
      Analytical solutions for the normal stress differences in large-amplitude oscillatory shear flow (LAOS), for continuum or molecular models, normally take the form of the first few terms of a series expansion in the shear ...
    • Padé Approximants for Large-Amplitude Oscillatory Shear Flow 

      Giacomin, A. Jeffrey; Saengow, Chaimongkol; Guay, Martin; Kolitawong, Chanyut (2015-03-17)
      Analytical solutions for either the shear stress or the normal stress differences in large-amplitude oscillatory shear flow, both for continuum or molecular models, often take the form of the first few terms of a power ...
    • Plastic Pipe Solidification: Exact Solutions in Cylindrical Coordinates 

      Saengow, Chaimongkol; Poungthong, P.; Kolitawong, Chanyut; Giacomin, A. Jeffrey (2015-12)
      For polymer melt solidification in plastic pipe extrusion, we perform an energy balance on the pipe extrudate in cylindrical coordinates to arrive at exact solutions for the temperature, and for the solidification rate. ...
    • Polymer Fluid Dynamics: Continuum and Molecular Approaches 

      Bird, R. Byron; Giacomin, A. Jeffrey (2016-06-20)
      To solve problems in polymer fluid dynamics, one needs the equation of continuity, motion, and energy. The last two equations contain the stress tensor and the heat-flux vector for the material. There are two ways to ...
    • Polymer Orientation Contributions in Large-Amplitude Oscillatory Shear Flow 

      Gilbert, Peter H.; Giacomin, A. Jeffrey (2017-01)
      Previously, we used a dilute suspension of rigid dumbbells as a model for the dynamics for polymeric liquids in large-amplitude oscillatory shear (LAOS) flow. We then use dumbbell orientation to explain fluid elasticity. ...
    • Polymer Processing Partitioning Approach: Extruding Plastic Pipe 

      Saengow, Chaimongkol (2016-01)
      The proposed thesis research aims at deepening our understanding of the flow of polymer melts through eccentric plastic pipe extrusion dies. Specifically, the proposed thesis research will explore how viscoelasticity affects ...
    • Power Series for Normal Stress Differences of Polymeric Liquids in Large-Amplitude Oscillator Shear Flow 

      Poungthong, P.; Giacomin, A. Jeffrey; Saengow, Chaimongkol; Kolitawong, Chanyut (2018-04)
      Exact solutions for normal stress differences in polymeric liquids subjected to largeamplitude oscillatory shear flow (LAOS) contain many Bessel functions, each appearing in infinite sums. For the simplest relevant model ...
    • Power Series for Shear Stress of Polymeric Liquid in Large-Amplitude Oscillatory Shear Flow 

      Poungthong, P.; Saengow, Chaimongkol; Giacomin, A. Jeffrey; Kolitawong, Chanyut (2018-04)
      xact solutions for shear stress in a polymeric liquid subjected to large-amplitude oscillatory shear flow (LAOS) contain many Bessel functions. For the simplest of these, for instance, the corotational Maxwell fluid, in ...
    • Reflections on Inflections 

      Saengow, Chaimongkol; Giacomin, A. Jeffrey; Gilbert, Peter H.; Kolitawong, Chanyut (2015-11-11)
      In plastics processing, the single most important rheological property is the steady shear viscosity curve: the logarithm of the steady shear viscosity versus the logarithm of the shear rate. This curve governs the volumetric ...
    • Review of Nonlinear Oscillatory Shear Flow Notations and Presentations: Polymeric Liquids 

      Saengow, Chaimongkol; Giacomin, A. Jeffrey (2018-12)
      We review notations for, along with ways of presenting, the shear stress responses to large-amplitude oscillatory shear flow (LAOS). We find that the Fourier loss and storage viscosities to be the simplest primal notations ...
    • Series Expansion for Shear Stress in Large-Amplitude Oscillatory Shear Flow From Oldroyd 8-Constant Framework 

      Poungthong, P.; Giacomin, A. Jeffrey; Saengow, Chaimongkol; Kolitawong, Chanyut (2018-06)
      When polymeric liquids undergo large-amplitude oscillatory shear flow (LAOS), the shear stress responds as a Fourier series, the higher harmonics of which are caused by the fluid nonlinearity, and the first harmonic of ...
    • Simple Accurate Expressions for Shear Stress in Large-Amplitude Oscillatory Shear Flow 

      Saengow, Chaimongkol; Giacomin, A. Jeffrey; Khalaf, N.; Guay, Martin (2017-05)
      Analytical solutions for shear stress in large-amplitude oscillatory shear flow (LAOS), for continuum or molecular models, often take the form of the first few terms of a power series in the shear rate amplitude. For ...
    • Slip Heating in Die Drool 

      Gilbert, Peter H.; Giacomin, A. Jeffrey (2014-05-14)
      When molten plastic is extruded from a die, it can collect on the open die face. Called die drool, this phenomenon costs plastics manufacturers by requiring shutdown for die cleaning. This has been attributed to cohesive ...
    • Slip Heating in Die Drool with Viscous Dissipation 

      Gilbert, Peter H.; Giacomin, A. Jeffrey (2014-10-06)
      Plastics can build-up on the die lip during extrusion. This phenomenon is called die drool and can be costly for plastics producers, requiring periodic shutdowns for die cleaning. Die drool has been attributed to the ...
    • Startup Steady Shear Flow from the Oldroyd 8-Constant Framework 

      Saengow, Chaimongkol; Giacomin, A. Jeffrey; Grizutti, Nino; Pasquino, R. (2019-01)
      One good way to explore fluid microstructure, experimentally, is to suddenly subject the fluid to a large steady shearing deformation, and to then observe the evolving stress response. If the steady shear rate is high ...
    • Temperature Rise in a Verging Annular Die 

      Younes, Georges R.; Giacomin, A. Jeffrey; Gilbert, Peter H. (2015-12-07)
      Plastic pipes, tubes or catheters are extruded by pressure‑driven flows through annular dies. Whereas die lands are straight, the section connecting the die land to the extruder either converges or diverges, converging ...
    • Transport Phenomena in Eccentric Cylindrical Coordinates 

      Gilbert, Peter H.; Saengow, Chaimongkol; Giacomin, A. Jeffrey (2016-09)
      Studies in transport phenomena have been limited to a select few coordinate systems. Specifically, Cartesian, cylindrical, spherical, Dijksman toroidal, and bipolar cylindrical coordinates have been the primary focus of ...