Steady Extension of Incompressible Simple Fluids

``Steady extension'' is a flow possible in every incompressible simple fluid (Newtonian, non-Newtonian, or viscoelastic) without neglect of inertia. A special example of this flow is realized by considering a cylindrical fluid mass which is being continually elongated (or shortened) at a rate proportional to its length. The behavior of a general simple fluid in steady extension is determined by material functions other than the viscosity and normal-stress functions which govern viscometric flows.