Szukana fraza: [Abstract = "The perturbations of these basic solutions are expressed in the form of three\-dimensional Tollmien\-Schlichting waves. The formulation of the stability problem leads to the Orr\-Sommerfeld equation modified by the permeability parameter \(Darcy number\) and the small Reynolds number. This equation is given in a general form which can be applied to the Chebyshev domain and the boundary layer domain and solved numerically using the Chebyshev spectral collocation method."]