Numerical simulations of viscoelastic tridimensional lid-driven cavity flows

Much is known about the dynamics of viscous Newtonian fluids in the classical “lid driven cavity” problem. However, little is known about the corresponding motion of viscoelastic fluids. The aim of this work is to study qualitatively and quantitatively the dynamics of viscoelastic flows for three different Deborah numbers in a tridimensional cavity. The so called “log-conformation formulation” made available by rheoTool for the OpenFOAM software is used to research the onset of elastic instabilities as an effect of viscoelasticity. The results obtained are presented through flow visualization and stress profiles. The symmetry observed in the velocity field of viscous Newtonian cavity flows at negligible Reynolds number is broken. The primary vortex centre shift progressively upstream with increasing Deborah number. The flow remains stable and two-dimensional with increasing Deborah number and no elastic instabilities appear. Upon the cessation of the moving wall motion, a pronounced elastic recoil is observed which leads to a rapid reversal in the recirculation direction. The elastic recoil subsequently decays through viscous dissipative effects.