Additive Layers: An Alternate Classification of Flow Regimes

TL;DR

This paper proposes a new classification of flow regimes based on the emergence of additive layers, including the wall, law of the wake, and log-law layers, to better understand flow transitions.

Contribution

It introduces an alternative classification of flow regimes by identifying three distinct layers associated with flow behavior and transition.

Findings

Flow regimes are characterized by the presence of specific layers.

The wall layer remains constant after reaching a critical viscous penetration.

Flow transition is marked by the emergence of new flow layers.

Abstract

It is argued that ejections of wall fluid in the bursting process disturb the flow beyond the wall layer and result in the emergence of two new layers in the flow field: the law of the wake and log-law layers. The wall layer represents the extent of penetration of viscous momentum into the main flow and remains constant once it has reached a critical value at the end of the laminar regime. The identification of the three flow regimes: laminar, transition and fully turbulent is conveniently achieved by monitoring the emergence of these three layers