Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published January 2016 | public
Conference Paper

Turbulence Amplitude Modulation in an Externally Forced, Subsonic Turbulent Boundary Layer


This paper describes an experiment in which a forced shear layer external to a turbulent boundary layer is used to impart external large-scale forcing to the boundary layer. The shear-layer forcing creates periodic coherent vortical structures in the shear layer that convect at the shear-layer convective velocity. The convecting coherent structures create a concomitant unsteady pressure field that provides a disturbance for the turbulent boundary layer on the upper wall of the tunnel above the forced shear layer. The unsteady pressure field in turn creates a variation of the effective freestream velocity experienced by the boundary layer, and both the pressure disturbance and the concomitant velocity fluctuations are reported. The character of the turbulence in the boundary layer due to the external forcing is studied through hot-wire anemometry. Thorough examination of the turbulence results in similarities between the turbulence amplitude modulation results due to these externally-forced experiments and modulation response of an internally-forced boundary layer done by others.

Additional Information

© 2016 AIAA. This effort were funded in part by the High Energy Laser - Joint Technology Office (HEL-JTO) and administered through the Air Force Office for Scientific Research (AFOSR) under Grant Number FA9550-13-1-0001. The U.S. Government is authorized to reproduce and distribute reprints for governmental purposes notwithstanding any copyright notation thereon.

Additional details

August 20, 2023
October 17, 2023