Influence of initial conditions on coherent structures in a round jet

TL;DR

This study investigates how initial turbulence conditions influence the formation of coherent structures in the near-field of a round jet, revealing that turbulence level at the inlet significantly affects their presence.

Contribution

It provides a numerical analysis comparing the effects of different initial turbulence states on coherent structures in round jets using a k-epsilon model.

Findings

Coherent structures are weaker or absent with fully developed inlet turbulence.

Underdeveloped turbulence at the inlet promotes stronger coherent structures.

Turbulence level at the inlet critically impacts near-field flow features.

Abstract

Coherent structures play an important role in the near-field of shear flows such as round jets. In the following the near-field of a round jet is numerically investigated , this for different initial conditions. Two configurations are considered one with a fully developed turbulence at the inlet, the other with an under developed turbulence. Calculations are carried out with a k-epsilon turbulence model but different sets of values for the constants inducing different level of diffusion within the flow. Finally, the results show that the presence of coherent structures in the near-field depends strongly on the turbulence level at the inlet. For a fully developed turbulence these structures are missing or very weak which is not the case for an under developed turbulence.