Revisiting the linear instabilities of plane channel flow between compliant walls

By revisiting the linear dynamics of plane channel flow between compliant walls it is shown that the instability is mainly dominated by perturbations of varicose symmetry. The prevailing modes are of traveling-wave-flutter type and governed by the reduced velocity, a nondimensional control parameter measuring the response of the flexible wall to hydrodynamic loading. Analysis of the energy transfer mechanisms reveals that a stabilizing effect for one class of modes is often accompanied by a destabilizing effect for another class. Thus it seems impossible to significantly delay instability onset by wall compliance.