Detection and analysis of solitons-like coherent structures in free round jet flow

Flow structures on free jet flow are investigated by means of the Direct Numerical Simulation method. The flow structures within the jet are investigated by tracking material lines and material surfaces using the Lagrangian tracer method. The timeline tracking results revealed the presence of high- and low-speed regions within the jet. Further studies utilizing material surface tracking reveal localized kinks, bulges, and depressions structures resembling soliton-like coherent structures (SCS) within both high- and low-speed regions. The evolution of these three-dimensional wave structures follow patterns similar to those of SCSs in flat-plate boundary layers. This finding provides evidence that SCSs are of dominated flow structures for the turbulent generation in shear flows.