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for values of the ratio n (R0 + R1) I (R0 - JR1) > 37
For smaller values of this ratio, Ga1111111118 has to be multiplied by the factor Pp given in
Figure 5.1. The height H and width W are obtained in this case from Equation 5.6 and
Equation 5.7.
5.1.1.2 Shear Rate in Die Channels
The shear rate for the channels treated above can be computed from [3]
The shear rate for an equilateral triangle is given by [4]
where d is the half length of a side of the triangle.
The relation for a quadratic cross-section is [4]
where a is the length of a side of the square.
(5.9)
(5.10)
(5.11)
(5.12)
(5.13)
In the case of channels with varying cross-sections along the die length, for example,
convergent or divergent channels, the channel is divided into a number of sufficiently
small increments and the average dimensions of each increment are used in the equations
given above [3].
5.1.1.3 General Relation for Pressure Drop in Any Given Channel Geometry
(5.8)
By means of the substitute radius defined by SCHENKEL [5] the pressure drop in crosssections
other than the ones treated in the preceding sections can be calculated. The
substitute radius is expressed by [5]