Radial flow between parallel discs

If two circular discs are separated by a distance 2h, with a pressure-drop P for radial flow between any two radii ai and 32, the flow rate is given by 

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Radial flow between parallel discs is a very common flow type encountered in polymer processing, particularly during injection mold filling. In this section, we seek the velocity profile, flow rates and pressure for this type of flow using the notation presented in Fig. 5.16. 

Radial Flow Between two Parallel Discs — Newtonian Model... 

The motion of a particle between two adjacent conical discs is shown schematically in Figure 7.11. The flow of the suspension is assumed to be divided equally between the spaces formed by the discs, so that the flow rate in each disc channel is equal to Q/n where Q is the throughput and n is the number of channels. The flow is also assumed to be in a radial plane (i.e. having the same angular velocity as the stack) and directed parallel to the surface of the discs. Under these conditions, the velocity of a particle of size x at radius r from the axis of rotation can be resolved into two components the radial velocity dr/dt, which can be approximated by Stokes law in equation 7.1, and the velocity in the direction of flow z dz/dt, which can be approximated by the velocity of the liquid at that point (if a plug flow is assumed)... 

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