The study presents a numerical investigation of unsteady plane channel flows of an elasto-viscoplastic material using the Herschel-Bulkley variant of the Saramito elasto-viscoplastic model [1] (SRM-HB), which incorporates both viscoelastic and viscoplastic behaviour. Yield stress fluids exhibit a dual nature, behaving as solids below a critical stress threshold and flowing as non-Newtonian fluids above it. This duality is crucial for numerous industrial applications and remains an area of active research. By examining the unsteady flow dynamics driven by steady and unsteady pressure gradients in a plane channel, this work evaluates the performance of the SRM-HB model against experimental data obtained with Carbopol gels. The findings highlight the significant role of elasticity in the yielding process and the resulting flow characteristics. Various flow scenarios, including creep tests, unsteady pressure ramps, and large-amplitude oscillatory flows, are analyzed to elucidate the complex interplay between elastic and plastic responses. The results demonstrate that the SRM-HB model effectively captures the transient flow behavior and hysteresis phenomena observed experimentally, providing insight into the material’s yielding and flow mechanisms.
