Channel Dimensions, Assumptions, and Basic Force Balances

1 Channel Dimensions Assumptions and Basic Force Balances 

All models are dependent on the differential slab in the z direction, as shown in Fig. A5.1. This figure shows the dimensions at the barrel wall, at the screw core, and the average. Like the nomenclature in other chapters including Chapter 5, the dimension at the screw core will have a subscript of c, dimensions at the barrel wall will have a subscript of b, and the average values when they occur will not be subscripted. The dimensions are shown here for clarity. These key dimensions will be removed from the force balance diagrams to follow. 

Campbell et al. and Yamamuro et al. assume a form for (or F ) and then determine the solids conveying angle (p. Hyun and Spalding calculated q using a force balance and two torque balances. Campbell and Dontula and Yamamuro et al. did not use a torque balance in their analysis. The following is a list of assumptions from all the models discussed. Additional assumptions will be added as needed. Assumptions that do not have keys were used by all authors  

Plug flow exists (the velocity of the polymer is constant in time and space) and the plug contacts all sides of the channel. 

The flight clearance (between the flight and the barrel) is neglected. 

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