On the Coupling Between a Supersonic Boundary Layer and a Flexible Surface


Book Description

The coupling between a two-dimensional, supersonic, laminar boundary layer and a flexible surface is studied using direct numerical computations of the Navier-Stokes equations coupled with the plate equation. The flexible surface is forced to vibrate by plane acoustic waves at normal incidence emanated by a sound source located on the side of the flexible surface opposite to the boundary layer. The effect of the source excitation frequency on the surface vibration and boundary layer stability is analyzed. We find that, for frequencies near the fifth natural frequency of the surface or lower, large disturbances are introduced in the boundary layer which may alter its stability characteristics. The interaction between a stable two-dimensional disturbance of Tollmien-Schlichting (TS) type with the vibrating surface is also studied. We find that the disturbance level is higher over the vibrating flexible surface than that obtained when the surface is rigid, which indicates a strong coupling between flow and structure. However, in the absence of the sound source the disturbance level over the rigid and flexible surfaces are identical. This result is due to the high frequency of the TS disturbance which does not couple with the flexible surface. Frendi, Abdelkader and Maestrello, Lucio and Bayliss, Alvin Langley Research Center NAS1-18605; RTOP 505-90-52-01...







Monthly Catalog of United States Government Publications


Book Description

February issue includes Appendix entitled Directory of United States Government periodicals and subscription publications; September issue includes List of depository libraries; June and December issues include semiannual index
















Instability, Transition, and Turbulence


Book Description

This volume contains the proceedings of the Workshop on In stability, Transition and Turbulence, sponsored by the Institute for Computer Applications in Science and Engineering (ICASE) and the NASA Langley Research Center (LaRC), during July 8 to August 2, 1991. This is the second workshop in the series on the subject. The first was held in 1989, and its proceedings were published by Springer-Verlag under the title "Instability and Transition" edited by M. Y. Hussaini and R. G. Voigt. The objectives of these work shops are to i) expose the academic community to current technologically im portant issues of transition and turbulence in shear flows over the entire speed range, ii) acquaint the academic community with the unique combination of theoretical, computational and experimental capabilities at LaRC and foster interaction with these capabilities, and iii) accelerate progress in elucidating the fundamental phenomena of transition and turbulence, leading to improved transition and turbulence modeling in design methodologies. The research areas covered in these proceedings include receptiv ity and roughness, nonlinear theories of transition, numerical simu lation of spatially evolving flows, modelling of transitional and fully turbulent flows as well as some experiments on instability and tran sition. In addition a one-day mini-symposium was held to discuss 1 recent and planned experiments on turbulent flow over a backward facing step.




Parallel Computational Fluid Dynamics '96


Book Description

In the last decade parallel computing has been put forward as the only computational answer to the increasing computational needs arising from very large and complex fluid dynamic problems. Considerable efforts are being made to use parallel computers efficiently to solve several fluid dynamic problems originating in aerospace, climate modelling and environmental applications.Parallel CFD Conferences are international and aim to increase discussion among researchers worldwide.Topics covered in this particular book include typical CFD areas such as turbulence, Navier-Stokes and Euler solvers, reactive flows, with a good balance between both university and industrial applications. In addition, other applications making extensive use of CFD such as climate modelling and environmental applications are also included.Anyone involved in the challenging field of Parallel Computational Fluid Dynamics will find this volume useful in their daily work.