On the linear stability of channel flow over riblets

1996 ◽  
Vol 8 (11) ◽  
pp. 3194-3196 ◽  
Author(s):  
Uwe Ehrenstein
Keyword(s):  
Linear Stability ◽  
Channel Flow

Electrohydrodynamic linear stability of two immiscible fluids in channel flow

2006 ◽  
Vol 51 (25) ◽  
pp. 5316-5323 ◽  
Author(s):  
O. Ozen ◽  
N. Aubry ◽  
D.T. Papageorgiou ◽  
P.G. Petropoulos
Keyword(s):  
Linear Stability ◽  
Channel Flow ◽  
Immiscible Fluids

Curvature- and rotation-induced instabilities in channel flow

1990 ◽  
Vol 210 ◽  
pp. 537-563 ◽  
Author(s):  
O. John E. Matsson ◽  
P. Henrik Alfredsson
Keyword(s):  
Reynolds Number ◽  
Linear Stability ◽  
Channel Flow ◽  
Stability Theory ◽  
Critical Reynolds Number ◽  
Secondary Instability ◽  
Linear Stability Theory ◽  
Curved Channel ◽  
Dean Vortices ◽  
Coriolis Effects

In a curved channel streamwise vortices, often called Dean vortices, may develop above a critical Reynolds number owing to centrifugal effects. Similar vortices can occur in a rotating plane channel due to Coriolis effects if the axis of rotation is normal to the mean flow velocity and parallel to the walls. In this paper the flow in a curved rotating channel is considered. It is shown from linear stability theory that there is a region for which centrifugal effects and Coriolis effects almost cancel each other, which increases the critical Reynolds number substantially. The flow visualization experiments carried out show that a complete cancellation of Dean vortices can be obtained for low Reynolds number. The rotation rate for which this occurs is in close agreement with predictions from linear stability theory. For curved channel flow a secondary instability of travelling wave type is found at a Reynolds number about three times higher than the critical one for the primary instability. It is shown that rotation can completely cancel the secondary instability.

scholarly journals Linear stability analysis and numerical simulation of miscible two-layer channel flow

2009 ◽  
Vol 21 (4) ◽  
pp. 042104 ◽  
Author(s):  
K. C. Sahu ◽  
H. Ding ◽  
P. Valluri ◽  
O. K. Matar
Keyword(s):  
Numerical Simulation ◽  
Stability Analysis ◽  
Linear Stability ◽  
Channel Flow ◽  
Linear Stability Analysis

scholarly journals Spatio-temporal linear stability of double-diffusive two-fluid channel flow

2012 ◽  
Vol 24 (5) ◽  
pp. 054103 ◽  
Author(s):  
Kirti Chandra Sahu ◽  
Rama Govindarajan
Keyword(s):  
Linear Stability ◽  
Channel Flow ◽  
Fluid Channel ◽  
Spatio Temporal ◽  
Two Fluid ◽  
Double Diffusive

Linear stability analysis of pressure-driven flows in channels with porous walls

2008 ◽  
Vol 604 ◽  
pp. 411-445 ◽  
Author(s):  
NILS TILTON ◽  
LUCA CORTELEZZI
Keyword(s):  
Stability Analysis ◽  
Linear Stability ◽  
Channel Flow ◽  
Porous Wall ◽  
Inertial Effects ◽  
Porous Layers ◽  
Wall Permeability ◽  
Porous Walls ◽  
The Stability ◽  
Pressure Driven

We present the three-dimensional linear stability analysis of a pressure-driven, incompressible, fully developed, laminar flow in a channel delimited by rigid, homogeneous, isotropic, porous layers. We consider porous materials of small permeability in which the maximum fluid velocity is small compared to the mean velocity in the channel region and for which inertial effects may be neglected. We analyse the linear stability of symmetric laminar velocity profiles in channels with two identical porous walls as well as skewed laminar velocity profiles in channels with only one porous wall. We solve the fully coupled linear stability problem, arising from the adjacent channel and porous flows, using a spectral collocation technique. We validate our results by recovering the linear stability results of a flow in a channel with impermeable walls as the permeabilities of the porous layers tend to zero. We also verify that our results are consistent with the assumption of negligible inertial effects in the porous regions. We characterize the stability of pressure-driven flows by performing a parametric study in which we vary the permeability, porosity, and height of the porous layers as well as an interface coefficient, τ, associated with the momentum transfer process at the interfaces between the channel and porous regions. We find that very small amounts of wall permeability significantly affect the Orr–Sommerfeld spectrum and can dramatically decrease the stability of the channel flow. Within our assumptions, in channels with two porous walls, permeability destabilizes up to two Orr–Sommerfeld wall modes and introduces two new damped wall modes on the left branch of the spectrum. In channels with only one porous wall, permeability destabilizes up to one wall mode and introduces one new damped wall mode on the left branch of the spectrum. In both cases, permeability also introduces a new class of damped modes associated with the porous regions. The size of the unstable region delimited by the neutral curve grows substantially, and the critical Reynolds number can decrease to only 10% of the corresponding value for a channel flow with impermeable walls. We conclude our study by considering two real materials: foametal and aloxite. We fit the porosity and interface coefficient τ to published data so that the porous materials we model behave like foametal and aloxite, and we compare our results with previously published numerical and experimental results.

Linear stability of stratified channel flow

1995 ◽  
Vol 21 (5) ◽  
pp. 733-753 ◽  
Author(s):  
W.C. Kuru ◽  
M. Sangalli ◽  
D.D. Uphold ◽  
M.J. McCready
Keyword(s):  
Linear Stability ◽  
Channel Flow
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