On the absolute instability in a boundary-layer flow with compliant coatings

✍ Scribed by Olivier Wiplier; Uwe Ehrenstein

• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 236 KB
• Volume: 20
• Category: Article
• ISSN: 0997-7546
• DOI: 10.1016/s0997-7546(00)01107-9

✦ Synopsis

The question of absolute instabilities occuring in a boundary-layer flow with compliant coatings is reassessed. Compliant coatings of the Kramer's type are considered. Performing a local, linear absolute/convective stability analysis, a family of spring-backed elastic plates with damping is shown to be absolutely unstable for sufficiently thin plates. The absolute instability arises from the coalescence between an upstream propagating evanescent mode and the Tollmien-Schlichting wave. To reinforce the local, linear stability results the global stability behaviour of the system is investigated, integrating numerically the full nonparallel and nonlinear two-dimensional Navier-Stokes system coupled to the dynamical model. Injecting Gaussian-type, spatially localized flow disturbances as initial conditions, the spatio-temporal evolution of wave packets is computed. The absolute stability behaviour is retrieved in the global system, for a compliant panel of finite length. It is demonstrated numerically that the global stability behaviour of the wall, triggered by finite-end-effects, may be independent of the disturbance propagation in the flow.