IAHR Document Library

« Back to Library Homepage « Proceedings of the 31st IAHR World Congress (Seoul, 2005)

Characteristics of Concentration Field in the Initial Region of a Jet in Coflow

Author(s): L. P. Xia; K. M. Lam

Linked Author(s): Kit Ming Lam

Keywords: LIF; Jet; Coflow; POD; ZFE

Abstract: The non-intrusive flow measurement and visualization technique of laser-induced fluorescence (LIF) was used to investigate quantitatively the mean and fluctuating characteristics of the scalar concentration field within the initial region of a submerged round jet in stagnant ambient and in a coflow. Experiments were conducted in a laboratory water basin. The time-varying concentration field was investigated from the analysis of a long sequence of LIF images. Mean flow properties as the length of the potential core, that is the zone of flow establishment (ZFE) of the jet, concentration half width of the jet and the centerline dilution have been determined. A shorter ZFE was found for a jet in the presence of a coflow. For a pure moment jet in a stagnant ambient, time-series analysis of the concentration fluctuations was carried out on the time sequences of LIF images using the proper orthogonal decomposition (POD) technique. The eigenvalues as well as eigenfunctions of the modes were computed. Consequently the energy partition among the eigenfunctions was addressed and the typical time fluctuations of the concentration field can then be reconstructed from the dominant eigenfunctions. This inclusion of time variations is helpful in enhancing the virtual reality of the computer visualizations of integral model prediction.


Year: 2005

Copyright © 2024 International Association for Hydro-Environment Engineering and Research. All rights reserved. | Terms and Conditions