TOPOLOGY OF A TURBULENT BOUNDARY LAYER WITH AND WITHOUT WALL SUCTION

Measurements of velocity and temperature fluctuations are made in a turbulent boundary layer with nominally zero pressure gradient for two different slightly heated wall conditions: impermeable and porous surfaces. The temperature fluctuations are measured at three points in the flow to permit the identification of two spatially coherent events: coolings and heatings. Conditional velocity vectors in the plane of mean shear are viewed in a reference frame which translates at a constant velocity. Conditioning is on coolings, heatings or a combination of these events. Sectional streamlines, derived from the velocity vector data, show a succession of critical points: saddles and unstable foci. Coolings are aligned with diverging separatrices through the saddles whereas heatings are identified with the foci. Coolings are associated with a large strain rate and also a large spanwise vorticity: this result seems consistent with the presence of hairpin vortices which extend to different distances from the wall. In contrast, the strain rate and spanwise vorticity are small at the foci. The stabilising influence of suction is observed in the topology of the organised motion and in the contribution from this motion to the conventional stresses, temperature variance and heat fluxes.

• Supplemental Notes:
  • J. Fluid Mechanics, 198 (1989), p. 429 (Jan.) [23 pp., 35 ref., 1 tab., 13 fig.]
• Authors:
  • Antonia, R A
  • Fulachier, L
• Publication Date: 1989

Language

• English

Subject/Index Terms

• TRT Terms: Boundary layer; Measurement; Temperature measurement; Turbulence; Velocity
• Subject Areas: Marine Transportation;

Filing Info

• Accession Number: 00695305
• Record Type: Publication
• Source Agency: British Maritime Technology
• Files: TRIS
• Created Date: Aug 14 1995 12:00AM