Statistical Description of The Turbulent Round Jet Developing Region Along Its Centerline


  • Mohd Rusdy Yaacob Faculty of Electrical Engineering, Universiti Teknikal Malaysia Melaka, Hang Tuah Jaya, 76100 Durian Tunggal, Melaka, Malaysia
  • Preben Buchhave Intarsia Optics, Sønderskovvej 3, 3460 Birkerød, Denmark
  • Clara Marika Velte Department of Mechanical Engineering, Technical University of Denmark, 2800 Kgs. Lyngby, Denmark


turbulent round jet, centerline measurements, laser doppler anemometer, turbulence modelling


Due to the technical measurement difficulties, analysis on the developing region of a turbulent round jet has been omitted despite its vast significance in explaining the establishment of the fully developed counterpart. With a self-developed novel and sophisticated laser Doppler system that can accurately measure high turbulence intensity flow with high spatial resolution and dynamics range, a turbulent round jet is mapped in terms of statistical moments along the centerline throughout and beyond the developing region. About 25-30 jet exit diameters downstream, turbulence begins to approach the fully developed state where the mean velocity and variance develop in parallel in a seeming equilibrium. Turbulence intensity is consequently observed to initially increase before levelling out when approaching the fully developed state. The downstream development of the measured spatial energy spectra and second-order structure functions further support these observations in that they begin to develop the Kolmogorov characteristic -5/3 and 2/3 slopes in the inertial subrange within the downstream distance of 25-30 jet exit diameters. The dissipation can be to a reasonable approximation extracted from the third-order structure functions from about 20 jet exit diameters and further downstream. The results should be useful for development of analytic and numerical turbulence models.




How to Cite

Yaacob, M. R. ., Buchhave, P. ., & Velte, C. M. . (2020). Statistical Description of The Turbulent Round Jet Developing Region Along Its Centerline. Journal of Advanced Research in Fluid Mechanics and Thermal Sciences, 64(2), 337–353. Retrieved from