Interfacial instability of turbulent two-phase stratified flow: Multi-equation turbulent modelling with rapid distortion

TL;DR

This paper develops a multi-equation turbulent model to analyze the linear stability of a turbulent gas-liquid interface, revealing how perturbation turbulent stresses influence wave growth and structure in different flow regimes.

Contribution

It introduces a novel model for wave-induced perturbation turbulent stresses and examines their effects on interfacial stability in turbulent two-phase flows.

Findings

Perturbation turbulent stresses have minimal impact on thin film wave growth.

PTS enhance maximum growth rates in deep-water wave scenarios.

Velocity structures are significantly affected by PTS, especially at longer wavelengths.

Abstract

We investigate the linear stability of a flat interface that separates a liquid layer from a fully-developed turbulent gas flow. In this context, linear-stability analysis involves the study of the dynamics of a small-amplitude wave on the interface, and we develop a model that describes wave-induced perturbation turbulent stresses (PTS). We demonstrate the effect of the PTS on the stability properties of the system in two cases: for a laminar thin film, and for deep-water waves. In the first case, we find that the PTS have little effect on the growth rate of the waves, although they do affect the structure of the perturbation velocities. In the second case, the PTS enhance the maximum growth rate, although the overall shape of the dispersion curve is unchanged. Again, the PTS modify the structure of the velocity field, especially at longer wavelengths. Finally, we demonstrate a kind of parameter tuning that enables the production of the thin-film (slow) waves in a deep-water setting.