Numerical study of unsteady pipe flow of an elastoviscoplastic fluid

Abstract

In this paper we investigate, numerically, unsteady Poiseuille flow of an elastoviscoplastic fluid. The material is described by the rheological model by Putz and Burghelea (2009). The model can describe an elastic solid regime for low stresses, a solid–fluid phase of stresses in the vicinity of the yield stress and a fully fluid regime for large stresses. We impose a time dependent pressure ramp with the form of a triangular function to drive the flow. We compare average velocity across the pipe as a function of pressure drop for different slip laws. We find that the solid–fluid transition is correlated to the slip-law used in the computations but the boundary conditions do not affect neither the deformation-rates nor stress at the bulk and the wall. • Unsteady pipe flow. • Elastoviscoplasticity. • Slip law.