Analysis of flow in processing operations

In the processing equipment of thermoplastics, many kinds of complicated flow configurations exist. The flow in a tapered die, for example, produces three components of deformation that due to flow from the reservoir into the die that due to telescopic shear within the die that to extensional flow within the die. These may be assumed separable and the separately calculated pressure drops may be added to give the total pressure drop. But in addition, each deformation mechanism contributes to post extrusion swelling. The components due to simple shear and extension at the die exit determine the swell ratio. 

Class of flow Shear Extensional Die entry Swell ratio 

Data from Powell (1974), Cogswell (1970), Cogswell and McGowan (1972) and Barrie (1970). 

Acierno D and Collyer AA (Eds), Rheology and Processing of Liquid Crystal Polymers , Chapmann and Hall, London, 1996. 

Astarita G, Marucci G and Nicolais L (Eds), Rheology , Vols. 1, 2 and 3, Plenum Press, New York, 1980. 

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