Towards the use of probability distribution function to describe the flow of fiber suspensions

 

Julien Férec and Gilles Ausias

Université Bretagne Sud, France

 

Abstract

 

This talk will focus on describing the flow of fiber suspensions since this kind of flow is largely encountered in manufacturing processes, for instance. The performances of these composites are directly related to the microstructure of the fibers that controls their mechanical and physical properties, such as stiffness, strength, electrical and thermal conductivities. After presenting some experimental rheological observations for commercial and model systems, we then provide some basic theoretical background on the modeling of fiber suspension in Newtonian and non-Newtonian matrices. Usually, closure approximations are required to well pose the problem in terms of moment-tensor equations. The use of tensors is efficient and convenient, but they have three main drawbacks. The first one is the loss of physics, the second one is the need to use a closure approximation and the third is the inability to simply develop models to describe non-Newtonian suspending fluid behaviors. Therefore, our recent developments, in considering non-Newtonian suspending fluids for instance, motivate us to directly use the probability distribution function in order to overcome these issues. Hence, we show some flows of fiber suspensions in 2D planar geometries (a parallel plate channel and a planar 4:1 contraction) and in 2D axisymmetric geometries (a circular pipe, a center-gated disk and the die swell). This talk aims to show the possibility of using the probability distribution function in the future to develop more physical modeling, such as the flow of non-homogeneous systems or the flow of semi-flexible fiber suspensions.  

 


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