Erscheint 4 Ausgaben pro Jahr
ISSN Druckformat: 1065-3090
ISSN Online: 1940-4336
Indexed in
COMPUTATIONAL VISUALIZATION OF SEPARATED/REATTACHED TRANSITIONAL FLOWS ON A BLUNT PLATE
ABSTRAKT
It is well known that large-scale organized motions, usually called coherent structures, exist in many transitional and turbulent flows (if not all). The topology and range of scales of those large-scale structures change widely from flow to flow such as counter-rotating vortices in wake flows, streaks and hairpin vortices in turbulent boundary layers. However, it is not well established what kind of large-scale structures exists in separated/reattached transitional flows.
Large-eddy simulation with a dynamic subgrid-scale model is employed in the current study to investigate the physics of transitional separating/reattaching flows over a blunt plate held normal to a uniform stream. The Reynolds number based on the uniform inlet velocity and the plate thickness is 6500. Statistics of the LES are found to be in acceptable agreement with the available experimental data in the laminar, transitional, and turbulent flow regions. The entire transition process leading to breakdown to turbulence has been shown by flow visualization and large-scale structures have been identified at different stages of the transition process of the separating/reattaching flow. The well-known hairpin vortices commonly associated with boundary-layer transition on a flat plate have been clearly shown at about the mean reattachment point and more large-scale structures are presented as well. The large-scale structures are noticed to persist a considerable distance downstream of reattachment before they eventually break into smaller-scale turbulent structures. In addition, it may shed light on the transition mechanisms and the nature of instabilities involved to understand the formation of these large-scale structures, their spatial and temporal evolution and eventual break-up into smaller structures.
-
Yang Zhiyin, Abdalla Ibrahim E., Effects of free-stream turbulence on large-scale coherent structures of separated boundary layer transition, International Journal for Numerical Methods in Fluids, 49, 3, 2005. Crossref
-
Dumouchel Christophe, On the experimental investigation on primary atomization of liquid streams, Experiments in Fluids, 45, 3, 2008. Crossref
-
Abdalla Ibrahim E., Cook Malcolm J., Yang Zhiyin, Numerical study of transitional separated–reattached flow over surface-mounted obstacles using large-eddy simulation, International Journal for Numerical Methods in Fluids, 54, 2, 2007. Crossref
-
Abdalla Ibrahim Elrayah, Yang Zhiyin, Cook Malcolm, Computational analysis and flow structure of a transitional separated-reattached flow over a surface mounted obstacle and a forward-facing step, International Journal of Computational Fluid Dynamics, 23, 1, 2009. Crossref
-
Kechiche Najah, Abbassi Ali, Filali Taoufik, Jay Jacques, Ben Aissia Habib, Spectral analysis of round jet instabilities at low Reynolds number, Mécanique & Industries, 10, 6, 2009. Crossref
-
Zaouali Yassine, Jay Jacques, Ben Aissia Habib, Visualisation et mesures expérimentales dans un jet rond évoluant à nombre de Reynolds modéré, Mécanique & Industries, 10, 6, 2009. Crossref
-
Roux A., Gicquel L.Y.M., Sommerer Y., Poinsot T.J., Large eddy simulation of mean and oscillating flow in a side-dump ramjet combustor, Combustion and Flame, 152, 1-2, 2008. Crossref
-
Gu Hailin, Yang Jianzhi, Liu Minghou, Study on the instability in separating–reattaching flow over a surface-mounted rib, International Journal of Computational Fluid Dynamics, 31, 2, 2017. Crossref
-
Gu Hailin, Liu Minghou, Li Xinlong, Huang Hongjie, Wu Yiqiang, Sun Feiyang, The Effect of a Low-Frequency Structure on Passive Scalar Transport in the Flow Over a Surface-Mounted Rib, Flow, Turbulence and Combustion, 101, 3, 2018. Crossref