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Showing 1 to 20 of 20 for “"Oldroyd-B"”.
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Numerical modelling of the Oldroyd-B fluid
… is to develop a 3D finite element model of the Oldroyd-B fluid for use in a complex geometry. The model is developed in deal.ii, which is a C++ finite element library. In addition to the standard finite element approach for the momentum equation, the discontinuous Galerkin method is used for the …
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Complex fluid dynamical computations via the Finite Volume Method
… model also easily reduces to the Oldroyd-B model under certain conditions of the material parameters. Since computations using the Oldroyd-B model have been extensively documented in the literature, we take advantage of the mathematical modelling connection between the …
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Simulation of blood flows in a stenosed and bifurcating artery using finite volume methods and OpenFOAM
… models for viscoelastic fluids include the OldroydB, Giesekus, Johnson-Segalman, Finitely Extensible Non-Linear Elastic (FENE), Phan-Thein-Tanner (PTT) models etc. Our Numerical approach is based on the finite volume methods implemented on the OpenFOAM platform. We employ the Giesekus, …
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Numerical Simulations of Viscoelastic Flows Using the Discontinuous Galerkin Method
… the Navier-Stokes equations coupled with the Oldroyd-B model. We solve the Navier-Stokes equations in skew-symmetric form using the mixed finite element method, and we solve the Oldroyd-B model using the discontinuous Galerkin method. The Crank-Nicolson scheme is used for the temporal …
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Enhanced Constitutive Theories for Classical Thermoviscoelastic Polymeric Fluids
… material coefficients. It is shown that Maxwell, Oldroyd-B, and Giesekus constitutive models can be described by a single constitutive theory. It is well established that the currently used Maxwell and Oldroyd-B models predict zero normal stress perpendicular to the flow direction. It is shown …
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Instability and Transition to Turbulence in Complex Viscoelastic Flows Overlying Porous Surfaces
… and wall permeability. A modified Darcy-Brinkman-Oldroyd-B model is developed to describe the flow behavior within and adjacent to porous media, incorporating fully coupled interfacial conditions between the free-fluid and porous domains. Using this framework, a comprehensive linear stability …
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A Spectral Element Method for Viscoelastic Fluid Flow
… 1 contraction channel for a fluid governed by an Oldroyd-B constitutive equation. The behaviour of the Oldroyd-B fluids in the contraction channel is investigated for various Weissenberg numbers. The numerical simulations show that the spectral element method with the EVSS approach is efficient …
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Tricks and tips for faster small-scale swimming: Complex fluids and elasticity
… waves in a viscoelastic fluid described by the Oldroyd-B constitutive relationship. Using Taylor’s swimming sheet model, we show that if all travelling waves move in the same direction, the locomotion speed of the organism is systematically decreased. However, if we allow waves to travel in two …
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Simulation of nonisothermal and time-dependent viscoelastic flows
… The linear stability of the flow of an Oldroyd-B model is analyzed with both the time integration methods and the hybrid time integration/Krylov algorithm for flow through several model geometries. First, the circular Couette problem is examined to benchmark the methods, and the …
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The solution of large viscoelastic flow problems using parallel iterative techniques
… differential constitutive model, e.g. the Oldroyd-B model, yields an asymmetric, nonsingular system of linear equations when nonlinearities are updated explicitly. Krylov iterations preconditioned with inexact solves in a two-level additive Schwarz framework are used to solve this system at …
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Fluid Mechanics for Biomedical Applications: Weakly Viscoelastic Electrospray, Flow Focusing and Collapsible Channel Models
… fluid, and a non-Newtonian one modelled using an Oldroyd-B model was performed, resulting in a better understanding of how the properties of this type of material influence aspects such as meniscus shrinking, the agreement with a 1D-slenderness model, or the minimum flow rate value defining the …
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Computational analysis of viscoelastic free surface flows
… the research involved the implementation of the Oldroyd-B constitutive equations and associated solution methods, in the 3-D multi-physics software environment PHYSICA+. This provides an unstructured finite volume solution technique for viscoelastic flow. This algorithm is validated using the 4:1 …
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Shear flow instabilities in viscoelastic fluids
… instability of Upper Convected Maxwell and Oldroyd–B fluids at zero Reynolds number in Couette flow. We show that if the Weissenberg number is large, the instability persists with the same growth rate when the wavelength is longer than the channel width. Intriguingly, surface tension does …
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Bubble dynamics in polymeric foams
… moulding. We use standard rheological models (Oldroyd B and Pompom) to investigate bubble growth driven by gas diffusion as a model for injection moulding. To model reaction injection moulding, we develop a new fluid model based on existing linear theory for a gelling liquid. In this case gas …
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Modeling of three-dimensional viscoelastic flows with free surfaces using a finite element method
… have been conducted in this geometry with the Oldroyd-B model, [beta] = 0.67, wall separation distances between 4-32 radii, and Deborah number 0.1 < De < 2.0. The range of bounding wall edge effects on the flow field is shown to be just under 4 cylinder radii. At De = 2.0, the simulation shows …
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Desenvolvimento de um método de volumes finitos de alta ordem para a simulação de escoamentos de fluidos viscoelásticos
… duas equações constitutivas, que são o modelo de Oldroyd-B e o modelo de Phan-Thien-Tanner Simplificado. Por estes resultados pode-se ver que a metodologia é muito promissora, apresentando algumas vantagens frente às metodologias convencionais em volumes finitos. A implementação atual da …
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Simulations of interfacial dynamics of complex fluids using diffuse interface method with adaptive meshing
… crystals. Viscoelasticity is represented by the Oldroyd-B model, derived for a dilute polymer solution as linear elastic dumbbells suspended in a Newtonian solvent. The Leslie-Ericksen model is used for nematic liquid crystals，which features distortional elasticity and viscous anisotropy. The …
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Numerical studies of Newtonian and viscoelastic fluids
… extensible nonlinear elastic (FENE) dumbbell and Oldroyd-B models. The finite element method (FEM) is used to discretize the flow domain. The DNS results show that the permeability of a periodic porous medium depends on the wavelength used for arranging particles in the direction of flow. …
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Computational studies of viscoelastic multiphase flows
… of viscoelastic two-phase flow problems. The Oldroyd-B constitutive equation is used to model the viscoelastic liquid. The code is used to study transient and steady state shapes of Newtonian and viscoelastic drops in simple shear and buoyancy driven flows. The roles of the governing …