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Showing 1 to 16 of 16 for “"Weissenberg number"”.
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Well-posedness results for a class of complex flow problems in the high Weissenberg number limit
… the Navier-Stokes equations in the high Reynolds number limit brings about two fundamental research subjects, the Euler equations and the Prandtl's system. The consideration of infinite Reynolds number reduces the Navier-Stokes equations to the Euler equations, both of which are dealing with the …
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Shear flow instabilities in viscoelastic fluids
… I studies inertialess coextrusion flows at large Weissenberg number where the instabilities are due to discontinuities in the elastic properties, and part II studies the effect of elasticity on the well-known inertial instabilities of inviscid flows with inflection points. We begin part I with a …
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A NUMERICAL STUDY OF NONLINEAR VISCOELASTIC FLOW AND NONISOTHERMAL POWER-LAW FLOW
… range for this fluid model, in terms of the Weissenberg number, beyond which elastic effects appear to become less dominant. The upstream vortex detachment length before the contraction is shown to grow with increasing Weissenberg number, and then reach a maximum value, until no converged …
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Simulation of nonisothermal and time-dependent viscoelastic flows
… flow at a critical value of the Weissenberg number (Mc Kinley, 1993 ). Contrary to experimental observations, the flow with the Oldroyd-B model is predicted to be stable for all values of the Weissenberg number investigated. We</=0. 75. The flow of the Oldroyd-B model around a …
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The design and construction of a novel pipe flow apparatus for exploring polymer drag reduction
… - the diffusion time. This ratio is known as the Weissenberg Number, and the role it plays in polymer drag reduction has not been explored experimentally in a systematic way. It has been known for some time that the slimes produced by fishes are effective drag reducing agents per unit weight; the …
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The Stability Properties of Some Rheological Flows
… are characterised by a critical Reynolds number which represents the ratio of inertial forces to viscous forces, and instability occurs when the inertial forces become large.<br/><br/>For non-Newtonian viscoelastic fluids the instability is characterised by a critical Weissenberg number, …
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Flow-Induced Self Assembly in Micellar Fluids with Applications to Nanomanufacturing
… of the salt concentration such that an effective Weissenberg number for the onset of shear thickening is practically independent of salt concentration. However, SIS are found to be extremely shear sensitive, and instantaneously disintegrate upon removal of applied strain. Based on this …
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Role of viscoelasticity and non-linear rheology in flows of complex fluids at high deformation rates
… whose importance is characterized by the Weissenberg number ... We develop a stability criterion for the onset of a purely viscoelastic instability for shear-banding fluids, to establish the limitations of conventional rheometric techniques for studying these fluids. A second challenge for …
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Instability and Transition to Turbulence in Complex Viscoelastic Flows Overlying Porous Surfaces
… four key dimensionless parameters: the Reynolds number (RRRR), Weissenberg number (WWWW), permeability parameter (αα), and solvent viscosity ratio (ββ). The analysis reveals a transition from viscoelastic Tollmien--Schlichting (TS)-type modes at low WWWW to a distinct elastic wall mode (EWM) …
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On the stability of plane viscoelastic shear flows in the limit of infinite Weissenberg and Reynolds numbers
… convected Maxwell model in the limit of infinite Weissenberg and Reynolds numbers. Specifically, we study the effects of elasticity on the instability of a few classes of simple parallel flows, specifically plane Poiseuille and Couette flows, the hyperbolic-tangent shear layer and the Bickley jet. …
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Capillary breakup of Discontinuously Rate Thickening Suspensions
… [epsilon]Wi, which is a function of the Weissenberg number Wi associated with the flow, and the aspect ratio of the filament . When [epsilon]Wi < 1/3, the viscous stress at the center of the filament scales as [epsilon]-1 and when [epsilon]Wi > 1/3, the viscous stress scales as Wi- 1. …
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Rheology and Flow Behaviour of Non-Newtonian, Polymeric Fluids in Capillaric and Porous Media: Aspects Related to Polymer Flooding for Enchanced Recovery of Heavy Oil
… elasticity, characteristic relaxation time and Weissenberg number. Sandpack flood results suggested that HAP polymers can exhibit lower Fr values at higher injection rate (easier to inject near wellbore) and higher Fr values at in-situ, reservoir flow rates, i.e. 0.3 m/d (1 ft/d). Immiscible …
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Development of an efficient finite volume computational platform for the simulation of complex flows of complex fluids governed by the Rolie-Poly model
… to stabilise the numerical algorithm at high Weissenberg number. For the 4:1 planar contraction flow, it is observed that the numerical results using the LCR stabilazation technique are in good agreement for a range of Weissenberg numbers whereas the DEVSS method shows good agreement for low …
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Rheological characterization of lubricants in automotive industries through development of a novel capillary breakup extensional rheometer
… new extensional rheometer is validated using a number of different fluid systems, including a rheologically well-studied Newtonian calibration fluid of glycerol and a series of aqueous food thickeners. Exploratory tests also show the capabilities and limitations of the device through a series of …
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Modeling of three-dimensional viscoelastic flows with free surfaces using a finite element method
… fluid with free surfaces at infinite capillary number. The code is an extension of the parallel methods developed by Caola et al. from two- to three-dimensional flows, a restructured and improved version of the three-dimensional code of Phillips based on the subproblem formulation. The free …
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Viscoelastic Fluid Modeling for Geophysical Applications in an Eulerian Framework
Geological processes in the Earth's lithosphere and upper mantle exhibit elastic behavior on short timescales and viscous behavior on long timescales, motivating the use of viscoelastic models for intermediate regimes. Such models are essential for capturing both stress accumulation and permanent …