Work

Entrainment mechanism in a turbulent offset jet

Year: 2025

Type: article

Abstract: In this study, a turbulent offset jet with an offset ratio of 5 and a Reynolds number of 7500 is numerically investigated using Large Eddy Simulation (LES), aiming to explore the entrainment mechanisms based on the characteristics of the turbulent/non-turbulent interface (TNTI). First, the distance from the mean position of the TNTI to the jet centerline increases significantly faster in the pre-attachment zone than in the wall jet zone, suggesting a stronger entrainment process in the former region. Second, the conditionally averaged profiles show larger jumps in the velocity and vorticity across the TNTI in the pre-attachment zone, thereby promoting the entrainment of fluid from the non-turbulent region into the turbulent region. Finally, the entrainment is further analyzed through the mechanisms of the nibbling and engulfment. The results show that the contribution of engulfment to the entrainment is less than 2 %, indicating that engulfment is not a significant mechanism in this flow. This indirectly suggests that entrainment is primarily driven by the nibbling process. By quantifying the nibbling flux, it is found that the nibbling flux in the pre-attachment zone is approximately double that observed in the wall jet zone, further explaining higher entrainment in the former region.

Source: Ocean Engineering

DOI: 10.1016/j.oceaneng.2025.122907

Authors: Lanbin Yang, Haijin Huang, Ming Chen, Xusheng Zhou, Peng Jiang

Institution: Chongqing Jiaotong University

Language: English

Topic: Fluid Dynamics and Turbulent Flows

Subfield: Computational Mechanics

Field: Engineering

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $4,150

Funders: National Natural Science Foundation of China, Chongqing Jiaotong University, Chongqing Research Program of Technological Innovation and Application Demonstration, National Key Research and Development Program of China