Numerical investigation of immiscible displacement and exchange flows under axial rotation

Immiscible displacement and exchange flows in inclined rotating pipes are simulated using volume-of-fluid methods and validated against experimental data. A comprehensive analysis across a broad parameter space reveals that axial rotation fundamentally restructures momentum transport and energy pathways through three generalized physical principles. First, rotation acts as a primary decelerator of the leading interfacial front, with its influence captured by a nonlinear scaling law coupling the Froude number (Fr) and the inverse Rossby number (1/Rb). Second, rotation suppresses buoyancy-driven recirculation zones; in stationary pipes, recirculation can occupy up to 50% of the cross-sectional area, whereas under rotation, this fraction diminishes to less than 5%, a stabilization effect described by power-law correlations. Finally, phase-specific turbulent kinetic energy budget and Lumley triangle analyses reveal that rotation restructures energy pathways, driving a topological regime transition from an oblate, two-component dominant state toward a more isotropic, prolate topology.