Stability analysis of the flow in a coflowing device

TL;DR

This paper investigates the stability of flow in a coflowing device, revealing that jet destabilization occurs before the tapering meniscus, and questions the applicability of linear stability analysis for predicting breakup.

Contribution

It provides experimental and theoretical evidence that linear stability analysis cannot fully predict jet breakup in coflowing devices due to transient effects and initial perturbations.

Findings

Jet destabilizes before the tapering meniscus.

Linear stability analysis does not predict polydisperse dripping.

Initial perturbations significantly influence jet breakup.

Abstract

We analyze the stability of the coflow configuration. The experiments and the global stability analysis show that the emitted jet always destabilizes before the tapering conical meniscus. This implies that the parameter conditions at which polydisperse dripping arises cannot be determined from the linear stability analysis of the steady jetting mode. Transient simulations show that the linear superposition of decaying eigenmodes triggered by an initial perturbation can lead to the jet breakup. The breakup process significantly depends on the initial perturbation. These results question the validity of the linear stability analysis as applied to the coflowing and other similar configurations.