On the stability of non-isothermal flow in channels
When polymer melts flow through narrow channel or small-orifice dies, highly unsteady or irregular flow have sometimes been observed even when the imposed boundary conditions are steady and uniform (Pearson, 1969).
rheological parameter of the fluid defined by eq.
dimensionless viscosity-temperature parameter defined by eq. 
rheological parameter defined by eq. 
distance between the two parallel plates, ft.
a thermal transfer coefficient (1/h)
length of the plates, ft.
Graetz number defined by eq. 
mean temperature as defined by eq. 
velocity vector with u x, u y, u z as component velocities
mean velocity vector as defined by eq. 
mean steady state axial velocity
- xy, z
Cartesian coordinate system
refers to wall condition
thermal diffusivity, ft2/h
effective thermal diffusivity tensor
dimensionless x coordinate
wave number in y direction
dimensionless wave number in y direction
viscosity of fluid
density of fluid
dimensionless velocity in x direction
growth rate of disturbances
dimensionless growth rate
- \(\mathop K\limits^ - \)
proportionality constant for heat generation in eq.
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