Nonlinear global modes in inhomogeneous mixed convection flows in porous media
| Autor: | M.N. Ouarzazi, Alexandre Delache, F. Mejni, G. Labrosse |
|---|---|
| Přispěvatelé: | Laboratoire de Mécanique de Lille - FRE 3723 (LML), Université de Lille, Sciences et Technologies-Centrale Lille-Centre National de la Recherche Scientifique (CNRS), Laboratoire d'Informatique pour la Mécanique et les Sciences de l'Ingénieur (LIMSI), Université Paris Saclay (COmUE)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université - UFR d'Ingénierie (UFR 919), Sorbonne Université (SU)-Sorbonne Université (SU)-Université Paris-Saclay-Université Paris-Sud - Paris 11 (UP11), Université de Lille, Sciences et Technologies-Ecole Centrale de Lille-Université de Lille-Centre National de la Recherche Scientifique (CNRS) |
| Rok vydání: | 2008 |
| Předmět: |
Physics
Mechanical Engineering absolute instability global modes Mechanics Condensed Matter Physics 01 natural sciences Instability 010305 fluids & plasmas Nonlinear system porous media Axial compressor Classical mechanics Mechanics of Materials Combined forced and natural convection 0103 physical sciences Boundary value problem 010306 general physics Porous medium mixed convection Stationary front Linear stability |
| Zdroj: | Journal of Fluid Mechanics Journal of Fluid Mechanics, Cambridge University Press (CUP), 2008, 595, pp.367-377. ⟨10.1017/S0022112007009159⟩ |
| ISSN: | 1469-7645 0022-1120 |
| DOI: | 10.1017/s0022112007009159 |
| Popis: | The aim of this work is to investigate the fully nonlinear dynamics of mixed convection in porous media heated non-uniformly from below and through which an axial flow is maintained. Depending on the choice of the imposed inhomogeneous temperature profile, two cases prove to be of interest: the base flow displays an absolute instability region either detached from the inlet or attached to it. Results from a combined direct numerical simulations and linear stability approach have revealed that in the first case, the nonlinear solution is a steep nonlinear global mode, with a sharp stationary front located at a marginally absolutely unstable station. In the second configuration, the scaling laws for the establishment of a nonlinear global mode quenched by the inlet are found to agree perfectly with the theory. It is also found that in both configurations, the global frequency of synchronized oscillations corresponds to the local absolute frequency determined by linear criterion, even far from the threshold of global instability. |
| Databáze: | OpenAIRE |
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