Convective Instabilities in the Coextrusion Process
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R. Valette
Abstract
This paper is devoted to the numerical study of the stability of the plane flow for two immiscible fluids obeying Maxwell constitutive equation in a channel of aspect ratio 8. For fixed viscosity and flow rate ratios, the shape and non-linear behavior of interfacial waves induced by small perturbations of the input flow rate are studied using finite element simulations for various elasticity stratifications. The stationary flow, close to a Poiseuille flow and presenting a flat interface is first computed. Then the interfacial wave generated by a pulse-like disturbance on entry flow rates is computed by using time dependent computations. It takes the shape of a wave packet which is amplified or damped while moving towards the die exit. In unstable cases, the maximum deviation increases with elasticity (the Weissenberg number). Interestingly, the elastic stratification between the two layers can counteract unstable waves due to viscous stratification.
© 2001, Carl Hanser Verlag, Munich
Articles in the same Issue
- Editorial
- Ninth of a Series Pioneer of the Modular Co-rotating Twin Screw Extruder–Rudolf Erdmenger (1911–1991)
- Internal Mixer
- The “New-Generation” Co-flow Intermeshing Internal Mixer
- Screw Extrusion/Continuous Mixers
- Twin Screw Compounding of PE-HD Wood Flour Composites
- A Transient Melting Model of Polymer Balls Sliding Against the Barrel
- Prediction of Screw Length Required for Polymer Melting and Melting Characteristics
- Melting of Polymer Blends in Co-rotating Twin Screw Extruders
- Melting of Polymer Blends in Co-rotating Twin Screw Extruders
- Melting of Polymer Blends in Co-rotating Twin Screw Extruders
- The Mapping Method for Mixing Optimization Part I: The Multiflux Static Mixer
- The Mapping Method for Mixing Optimization
- Reactive Processing
- Comparison Studies of Anionic Polymerization of Caprolactam in Different Twin Screw Extruders
- Compatibilization of SBR/NBR Blends Using Chemically Modified Styrene Butadiene Rubber
- Coextrusion
- Convective Instabilities in the Coextrusion Process
- Numerical Simulation of Polymer Coextrusion Flows
- Thermoforming
- Tight Tolerance Thermoforming
Articles in the same Issue
- Editorial
- Ninth of a Series Pioneer of the Modular Co-rotating Twin Screw Extruder–Rudolf Erdmenger (1911–1991)
- Internal Mixer
- The “New-Generation” Co-flow Intermeshing Internal Mixer
- Screw Extrusion/Continuous Mixers
- Twin Screw Compounding of PE-HD Wood Flour Composites
- A Transient Melting Model of Polymer Balls Sliding Against the Barrel
- Prediction of Screw Length Required for Polymer Melting and Melting Characteristics
- Melting of Polymer Blends in Co-rotating Twin Screw Extruders
- Melting of Polymer Blends in Co-rotating Twin Screw Extruders
- Melting of Polymer Blends in Co-rotating Twin Screw Extruders
- The Mapping Method for Mixing Optimization Part I: The Multiflux Static Mixer
- The Mapping Method for Mixing Optimization
- Reactive Processing
- Comparison Studies of Anionic Polymerization of Caprolactam in Different Twin Screw Extruders
- Compatibilization of SBR/NBR Blends Using Chemically Modified Styrene Butadiene Rubber
- Coextrusion
- Convective Instabilities in the Coextrusion Process
- Numerical Simulation of Polymer Coextrusion Flows
- Thermoforming
- Tight Tolerance Thermoforming
