Aerodynamically-driven rupture of a liquid film by turbulent shear flow

TL;DR

This study investigates how turbulent shear flows cause liquid film rupture using numerical simulations, highlighting aerodynamic effects like lift forces that lead to film failure.

Contribution

It introduces a simplified numerical setup to systematically analyze the aerodynamic deformation and rupture of liquid films under turbulent shear conditions.

Findings

Cumulative lift force correlates with film rupture.

Velocity scale from lift-induced drag reflects turbulence effects.

Pressure field analysis reveals key aerodynamic forces involved.

Abstract

The rupture of a liquid film due to co-flowing turbulent shear flows in the gas phase is studied using a volume-of-fluid method. To simulate this multiphase problem, we use a simplified numerical setup where the liquid film is 'sandwiched' between two fully developed boundary layers from a turbulent channel simulation. The film deforms and eventually ruptures within the shear zone created by the co-flows. This efficient setup allows systematic variation of physical parameters to gauge their role in the aerodynamically-driven deformation and rupture of a liquid film under fully developed sheared turbulence. The present work presents a detailed study of the developing pressure field over the deforming film and related aerodynamic effects, as previously suggested by other authors, in particular the role of the inviscid lift and drag forces. A cumulative lift force is introduced to capture the effect of the alternating pressure minima and maxima forming over the film which amplify and eventually rupture the film. A velocity scale derived from the lift-induced drag force reflects the state of the turbulent boundary layer over the film and collapses the temporal development of this cumulative lift force as well as the amplitude of film deformation with some success for the different film thicknesses and Reynolds numbers.