The use of POD filtering to study the transition from 2D to 3D in stratified two- phase flow

Hann, David B; Loizou, Katerina; Vasques, Joao; Tokarev, Mikhail P; Cherdantsev, Andrey V

Abstract

The understanding of the velocity profile beneath waves in sheared flow can have implications for the understanding of heat transfer in many applications. In this paper an analysis of the velocity field beneath 2D and 3D waves is performed to understand the differences in the behavior. A drop in the average wall shear stress is identified when the gas flow rate increases past 3m/s and the flow transitions from 2D to 3D waves. POD filtering is employed to reconstruct the PIV series and remove much of the PIV processing noise to aid in the understanding of higher order statistics. Filtering levels were put at between 90-97% depending on the flow situation. It is demonstrated that in the 3D case, the instantaneous wall shear stress can be negative despite a positive average value leading to circulations beneath the trough. There is enhanced interfacial shear above the crest and this could lead to the flow reversal due to continuity. Some further turbulent statistics are considered to see the effect of the POD filtering on the results and there appears to be some promise in that approach, although further work will need to be done to ascertain the exact impact.

Citation

Hann, D. B., Loizou, K., Vasques, J., Tokarev, M. P., & Cherdantsev, A. V. (2018, July). The use of POD filtering to study the transition from 2D to 3D in stratified two- phase flow. Presented at 19th International Symposium on the Application of Laser and Imaging Techniques to Fluid Mechanics, Lisbon, Portugal

• Presentation Conference Type: Edited Proceedings
• Conference Name: 19th International Symposium on the Application of Laser and Imaging Techniques to Fluid Mechanics
• Start Date: Jul 16, 2018
• End Date: Jul 19, 2018
• Acceptance Date: Jul 1, 2018
• Publication Date: 2018
• Deposit Date: Oct 9, 2024
• Publicly Available Date: Oct 30, 2024
• Peer Reviewed: Peer Reviewed
• Book Title: Proceedings of the 19th International Symposium on Application of Laser and Imaging Techniques to fluid Mechamnics
• ISBN: 978-989-20-9177-8
• Keywords: PIV processing; two-phase sheared flow; POD
• Public URL: https://nottingham-repository.worktribe.com/output/1338333
• Publisher URL: https://www.lisbon-lasersymposium.org/lxlaser2018