Stability of extensional flows and extending viscoelastic fluid sheets (Q1064198)

The stability of extensional flows is studied on the basis of the theory of nearly-extensional flows developed for incompressible simple viscoelastic fluids under the assumption of ''short memory'' effects. The corresponding constitutive equations are used in a stability analysis of non-Newtonian fluid sheets, following the method presented by \textit{W. Minoshima} and \textit{J. L. White} for Newtonian fluids [ibid. 11, 127-145 (1982; Zbl 0497.76030)]. The theoretical considerations are made more specific for integral constitutive equations and in such a case the influence of elasticity on the stability of fluid sheets is numerically investigated. It is shown that the stability essentially depends on the product of the fluid relaxation time and the rate of extension. For the uniaxial extension of fluid sheets, the flow is stable, if the above mentioned product has values between 0.37 and 1.05 or greater than 4.04.