Effect of Taylor rolls on two-fluid turbulent Taylor-Couette flow

We conducted direct numerical simulations of two immiscible and incompressible fluids in a Taylor-Couette configuration. The Taylor number was set at 10⁸, while we varied the volume fraction and the Weber number to explore the interaction between the interfacial structures and the underlying turbulent flow field.

We find the presence of the secondary phase always increases the normalized torque compared to the reference single-phase case, which is attributed to the additional energy needed to keep the surface stretched. The torque computed numerically shows a clear deviation from an experimental work by Yi et al., JFM(912), 2021, which is explained by the effect of surfactants.

By investigating the flow fields, we observe that the secondary phase prefers to remain in the cores of the Taylor rolls and is almost absent from the plume-ejecting and -impacting regimes where the momentum is actively exchanged. This phase segregation results in totally different roles played by the two phases in the momentum transfer, highlighting an effect of the Taylor rolls on the interfacial dynamics.