Existence of steady solution from unsteady flow of viscoelastic fluid due to different pressure waveform in a circular cylinder

This work is to examine theoretically unsteady flow of viscoelastic fluid in a circular cylinder and to investigate the existence of steady solutions. We consider the flow is solely due to pressure gradient in following three forms: (i) sinusoidal; (ii) square; (iii) constant. Based on the pressure gradient described, three flow situations are solved and the exact analytical solutions are given in terms of Bessel functions. In all the three problems, it is found that the variation of the unsteady and steady solution mainly depends for small time, while for large time the two solutions are identical.