|type de publication
||article dans une revue internationale avec comité de lecture
|date de publication
||Mejni Fatah; Ouarzazi Mohamed Najib|
||Mechanics Research Communication (Mech Res Comm)
| || |
||260 – 264
||We study the nonlinear dynamic of mixed convection in semi-infinite porous media
heated non uniformly from below and through which an axial flow is maintained.
Because the imposed inhomogeneous temperature profile varies slowly downstream,
the WKBJ expansion is used specifically to determine the local absolute instability.
Direct numerical simulations are carried out in the the case when the inhomogeneity
promotes sufficiently extended absolute instability at the inlet. It is found that the
frequencies in the oscillating region are identical to the absolute frequencies at the
inlet. Moreover, the distance separating the inlet to the spatial position where the
trailing front of the globally unstable waves saturated is found to obey to a well
defined scaling law.
||global instabilities, porous media, mixed convection, inhomogeneous systems.