A comparative study of viscous flow in slit-exit cross-section dies using network analysis
Sprache des Vortragstitels:
Advances in Polymer Science and Technology (APST) 2
Sprache des Tagungstitel:
The use of polyolefins has been growing steadily for decades and the trend continues. One important growth area is the extrusion of sheets which may be used for further fabrication such as thermoforming, machining, welding, and laminating.
Flat dies (i.e., coathanger, fishtail, tee) are widely used in industry for the production of plastic films and sheets. The design of such dies is rather complex and requires a thorough understanding of the flow in the die. Both the geometrical and material quality of the products is governed by the uniformity of flow rate and residence time distributions. To satisfy these conditions, the optimal design of the extrusion dies is of great importance.
Computational Fluid Dynamics (CFD) is a powerful tool used by polymer processing industries in order to evaluate polymeric fluid flows. In this work, a modified finite vol-ume method, the so-called network analysis will be investigated.
This numerical method allows a flow problem in a complex geometry to be solved by subdividing the manifold into smaller parts having a simple geometry, of which analytical formulae based on constitutive equations are available. The resulting two-dimensional flow resistance network can be solved in analogy to the network analysis of electrical circuits.
A systematic approach based on Kirchhoff?s laws for the analysis of complex networks using tensor algebra and numerical methods (such as fixed point iteration) is presented. Finally, coathanger, fishtail and T-manifolds are compared in respect of mass flow, residence time and shear rate. In addition, a three-dimensional simulation using the commercially available software ANSYS Fluent was performed. The results turned out to be in good accordance with the numerical study mentioned above.