Comment on "The role of wetting heterogeneities in the meandering instability of a partial wetting rivulet"

TL;DR

This paper critically examines previous claims about rivulet meandering instability, providing experimental evidence that contradicts earlier theories and highlighting the influence of flow-rate perturbations.

Contribution

It offers a new experimental perspective challenging existing theories on rivulet meandering and discusses the limitations of current models.

Findings

Contradicts previous theory linking meandering to flow rate instability.

Shows flow-rate perturbations persist and affect rivulet behavior.

Highlights discrepancies between experimental results and existing models.

Abstract

Rivulets and their meandering on a partially wetting surface present an interesting problem, as complex behavior arises from a deceptively simple setup. Recently Couvreur and Daerr suggested that meandering is caused by an instability developing as the flow rate $Q$ increases to a critical value $Q_c$, with stationary (pinned) meandering being the final state of the flow. We tried to verify this assertion experimentally, but instead produced results contradicting the claim of Couvreur and Daerr. The likely reason behind the discrepancy is the persistence of flow-rate perturbations. Moreover, the theory presented in this paper cannot reproduce the states as considered and disagrees with other theories.