Analysis of Secondary Flows and Heat Transfer in Viscoelastic Flow With Viscous Dissipation in Non-Circular Tubes

2012 ◽  
Author(s):  
Mario F. Letelier ◽  
Fernando N. Zapata ◽  
Dennis A. Siginer ◽  
Juan Stockle
Keyword(s):  
Viscous Dissipation ◽  
Equations Of Motion ◽  
Viscoelastic Behavior ◽  
Weissenberg Number ◽  
Secondary Flows ◽  
Perturbation Approach ◽  
Axially Symmetric ◽  
Cross Sectional ◽  
Non Linear ◽  
Linear Viscoelastic

The steady laminar non-isothermal flow of a non-linear viscoelastic fluid in tubes or arbitrary contour is analyzed under constant wall heat flux. Viscous dissipation is taken into account. Non-linear viscoelastic behavior is modeled by means of the Phan-Thien-Tanner model. The equations of motion and energy are solved analytically through a perturbation approach coupled with a one-to-one mapping of the boundary to map the circular shape into various axially symmetric cross-sectional shapes with the Weissenberg number as the perturbation parameter Longitudinal and transversal velocity components are determined for several cross-sectional shapes, for which the temperature field and the Nusselt number variation with the Prandtl, Brinkman and Reynolds numbers are computed.

Secondary Flows in Straight Non-Circular Tubes: Giesekus Fluid

2013 ◽  
Author(s):  
Mario F. Letelier ◽  
Dennis A. Siginer ◽  
Juan Stockle
Keyword(s):  
Continuous Mapping ◽  
Weissenberg Number ◽  
Secondary Flows ◽  
Axially Symmetric ◽  
Third Order ◽  
Cross Sectional ◽  
Circular Tubes ◽  
The Third ◽  
Giesekus Fluid ◽  
Circular Base

Flow of Giesekus fluids in straight, arbitrary but axially-symmetric non-circular tubes is investigated. The cross-sectional shapes are obtained through a one-to-one continuous mapping of the circular base contour. The primary longitudinal and the secondary fields are elucidated up to and including the third order in the Weissenberg number Wi.

Viscoelastic Behavior of Carbon Nanotube Yarns and Twisted Coils

2018 ◽  
Author(s):  
Pouria Khanbolouki ◽  
Mehran Tehrani
Keyword(s):  
Carbon Nanotube ◽  
Viscoelastic Model ◽  
Viscoelastic Behavior ◽  
Energy Harvesters ◽  
Linear Behavior ◽  
Non Linear ◽  
Stretchable Conductors ◽  
Linear Viscoelastic Behavior ◽  
Linear Viscoelastic ◽  
Development And Validation

Coiled structures made from polymer and Carbon Nanotube (CNT) yarns are used as artificial muscles, stretchable conductors, and energy harvesters. The purpose of this work is to present our latest understanding of the mechanical behavior of these CNT-based structures. CNT yarns are fabricated by inserting twists in sheets spun from CNT forests. Over twisting the CNT yarns results in coiled CNT yarns, similar to a spring where the spring radius is comparable to the diameter of the CNT yarn. In this study, we explain the development and validation of a viscoelastic model, to capture damping and hysteresis in CNT yarns under quasi-static and dynamic loads. Confirmation of linear viscoelastic behavior of CNT yarns can lead us to the development of a model for coiled CNT yarns. Coiled CNT yarns, on the other hand, show a complex non-linear viscoelastic behavior. Possible mechanisms responsible for this non-linear behavior are discussed.

Non-linear viscoelastic behavior of fumed silica suspensions

1999 ◽  
Vol 38 (1) ◽  
pp. 14-25 ◽  
Author(s):  
F. Yziquel ◽  
P. J. Carreau ◽  
P. A. Tanguy
Keyword(s):  
Fumed Silica ◽  
Viscoelastic Behavior ◽  
Non Linear ◽  
Linear Viscoelastic Behavior ◽  
Linear Viscoelastic ◽  
Silica Suspensions

Characterizing Gum Elastomers by Fourier Transform Rheometry

2003 ◽  
Vol 76 (4) ◽  
pp. 979-1000 ◽  
Author(s):  
Jean L. Leblanc ◽  
Christophe de la Chapelle
Keyword(s):  
Fourier Transform ◽  
High Strain ◽  
Dynamic Testing ◽  
Harmonic Component ◽  
Viscoelastic Behavior ◽  
Strain Range ◽  
Polymer Materials ◽  
Range Data ◽  
Non Linear ◽  
Linear Viscoelastic

Abstract Fourier transform (FT) rheometry is an emerging new technique that allows the linear and non-linear viscoelastic behavior of polymer materials to be accurately investigated. Basically samples are submitted to torsional harmonic strain at fixed frequency and temperature in order to capture strain and torque signals. A commercial instrument, i.e. the Rubber Process Analyzer RPA 2000® (Alpha Technologies), was suitably modified, essentially in using a fast electronic analogic-digital conversion card to record and treat torque and strain signals using purposely written software. Details of such modifications were previously published and the work presented is a sequel of this development. The quality of the applied strain is first precisely documented through FT and found excellent, particularly in the high strain range. Three gum EPDM with different macromolecular characteristics (MWD and long chain branching) were analyzed either using standard dynamic testing, i.e. essentially in the linear viscoelastic range, or using the Fourier transform rheometry approach, by considering data gathered in the far non-linear viscoelastic range. Data obtained are considered with respect to know features of the samples. A series of SBR 1500 samples, collected from various manufacturers, were first analyzed using standard methods; as expected very small differences were seen. Then FT was used to consider torque signals at very high strain (up to 400% at 1 Hz). Using a simple 4-parameter model to treat the variation upon increasing strain of the relative third harmonic component of the torque signal, differences are clearly detected that are discussed with respect to available polymer manufacturing information.

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