Distributed-Roughness-Induced Transient Growth in a Flat Plate Boundary Layer Conference Paper uri icon


  • Surface roughness affects boundary layer transition in several ways, including acting as a receptivity mechanism for transient growth. Several experiments have measured transient growth created by discrete roughness elements; however, very few experiments have studied transient growth initiated by distributed surface roughness. In the present work, transient growth created by streamwise-extended patches of randomly distributed, sub-critical surface roughness is measured in a Blasius boundary layer. A deterministic roughness surface was manufactured using rapid prototyping, and detailed measurements of the roughness wake were made using hotwire anemometry. The distributed roughness creates disturbances at multiple spanwise wavelengths that undergo transient growth. These experiments lay the ground work for examining the "shielding" effect, wherein the presence of smaller amplitude distributed roughness may decrease the strength of roughness wakes created by larger roughness peaks.

author list (cited authors)

  • Kuester, M. S., & White, E. B.

citation count

  • 5

publication date

  • June 2013