“…For example, it can be shown theoretically that the pipe flow of a viscous fluid comes to rest in an infinitely long time [18], while the flow of Bingham fluid and more general viscoplastic fluids (including Casson and Herschel-Bulkley fluids) takes a finite amount of time to do so [19,20,23], if the pressure gradient falls below the critical value needed to overcome the yield stress effect. Indeed, the numerical modelling of cessation of the Poiseuille flow of the Papanastasiou fluid shows that when the imposed pressure gradient is non-zero and below the critical value, a steady non-trivial Poiseuille flow still persists [21]. When one uses a regularised method to develop a stopping criteria in steady flows, the situation is similar; see Fig.…”