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<p>This study examines the fluid dynamics of rectangular orifice synthetic jets using large eddy simulation (LES) with the Smagorinsky–Lilly model, performed in ANSYS Fluent with water as the working medium. Three cases of diaphragm displacements—1.6&#xa0;mm, 2.6&#xa0;mm, and 3.6&#xa0;mm—were investigated, corresponding to Reynolds numbers (<i>Re</i>) of 320, 543, and 746 and Strouhal numbers (<i>St</i>) of 0.31, 0.19, and 0.13, respectively. Numerical results were validated against experimental observations, demonstrating strong qualitative agreement in key flow features. The findings indicate that increasing the Reynolds number at a fixed actuation frequency enables curling shear layers to escape from the suction region, promoting the formation of coherent vortex rings. Notably, for <i>Re</i> = 320 and <i>St</i> = 0.31, bifurcation was observed at approximately 2.5 times the orifice diameter, with counter-rotating vortices spreading 0.5 times farther downstream compared to experimental results. Higher Reynolds numbers enhanced vortex ring formation due to the increased escape of curling shear layers from the suction region. Axial switching and bifurcation dynamics were characterized by divergent velocities between the vortex core and the ring center. These findings contribute to a deeper understanding of synthetic jet vortex dynamics, emphasizing the importance of three-dimensional insights for capturing the intricacies of vortex ring bifurcation and formation.</p> Graphical abstract <p></p>

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Large eddy simulation of rectangular synthetic jets and insights into vortex bifurcation dynamics

  • 期刊论文

  • 发表日期：

    2025年2月7日

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  • Abhay Kumar,
  • Ramesh K Donga,
  • Ashish Karn

摘要

This study examines the fluid dynamics of rectangular orifice synthetic jets using large eddy simulation (LES) with the Smagorinsky–Lilly model, performed in ANSYS Fluent with water as the working medium. Three cases of diaphragm displacements—1.6 mm, 2.6 mm, and 3.6 mm—were investigated, corresponding to Reynolds numbers (Re) of 320, 543, and 746 and Strouhal numbers (St) of 0.31, 0.19, and 0.13, respectively. Numerical results were validated against experimental observations, demonstrating strong qualitative agreement in key flow features. The findings indicate that increasing the Reynolds number at a fixed actuation frequency enables curling shear layers to escape from the suction region, promoting the formation of coherent vortex rings. Notably, for Re = 320 and St = 0.31, bifurcation was observed at approximately 2.5 times the orifice diameter, with counter-rotating vortices spreading 0.5 times farther downstream compared to experimental results. Higher Reynolds numbers enhanced vortex ring formation due to the increased escape of curling shear layers from the suction region. Axial switching and bifurcation dynamics were characterized by divergent velocities between the vortex core and the ring center. These findings contribute to a deeper understanding of synthetic jet vortex dynamics, emphasizing the importance of three-dimensional insights for capturing the intricacies of vortex ring bifurcation and formation.

Graphical abstract