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Delayed die swell as a problem of instability. (English) Zbl 0793.76009

Summary: The delayed viscoelastic die swell phenomenon, i.e. an experimentally observed change of curvature (an inflection point) in the jet profile is treated as a problem of “instability” caused by disturbed boundary conditions at the exit. The conditions of the delayed die swell in the form of inequalities, satisfied by the corresponding increments of forces and velocities, are considered. Axial and radial viscosity variations implied by admissible temperature distributions are also taken into account. Effects of inertial and air-drag forces on the delayed die swell are discussed in greater detail.

MSC:

76A10 Viscoelastic fluids
76E99 Hydrodynamic stability
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