Our study was motivated by simulating primary cementing processes. We examine immiscible displacement flows in stationary and rotating pipes, at a fixed inclination angle with a density-unstable configuration, using a viscoplastic fluid to displace a less viscous Newtonian fluid. The study focuses on the effects of critical dimensionless numbers, including the imposed Reynolds numbers (Re), inverse Rossby number (1/Rb), rotational Reynolds number (Rer), capillary number (Ca), and viscosity ratio (M), on flow patterns, regime classifications. Notably, distinct flow patterns emerged in both stationary and rotating pipes. In the case of stationary pipes, we identified lift-head and wavy interface stratified flows (Ia, Ib). In rotating pipes, we classified the displacement flows into several categories: swirling slug flow (II), swirling dispersed droplet flow (III), swirling fragmented flow (IV), and swirling bulk flow (V). Additionally, within the swirling slug flow regimes, we observed the stable (IIa), elongated (IIb), and chaotic (IIc) slug flow sub-regimes.
This work is licensed under the Creative Commons Attribution-NonCommercial 4.0 International License. Any reuse must credit the author(s) and provide a link back to this page.