Numerical and analytical modeling of unsteady viscoelastic flows: The start-up and pulsating test case problems

Then, a pulsating flow problem was studied. In this test case the flow is generated by a periodic pressure-gradient superimposed on a constant Poiseuille flow. The analytical solution for pulsatile Oldroyd-B flow in a channel was derived as part of the work and, again, difficulties in obtaining accurate numerical solutions with the UCM model were encountered, being necessary to employ extremely refined meshes. For the Oldroyd-B fluid no difficulties were found and the accuracy tended to improve with larger solvent viscosity parameter.