Effects of the separating shear layer on the reattachment flow structure Part 1: Pressure and turbulence quantities

✍ Scribed by E. W. Adams; J. P. Johnston

• Publisher: Springer
• Year: 1988
• Tongue: English
• Weight: 853 KB
• Volume: 6
• Category: Article
• ISSN: 0723-4864
• DOI: 10.1007/bf00196485

✦ Synopsis

The effect of the separating shear-layer thickness and shape on the structure of the flow in the reattachment region of a backward-facing step is examined using wall static-pressure profiles and turbulence data for a range of Reynolds number (800 < Reh, < 40,000) and upstream boundary-layer thickness (0 < 6/H < 2). The reattachment pressure and the peak pressure in the reattachment zone decrease in a continuous manner as the upstream boundary layer thickens. The thinnest boundary layers follow the correlation of Roshko and Lau. Using the pressure data, correlations are developed which can be used to predict the level of turbulent shear stress in the near-wall region at reattachment, a location in which experimental data are extremely difficult to obtain.

List of symbols

Notation

Cp

pressure coefficient, Ap/0.5 0 U~er Cp* r normalized pressure coefficient, Eq. ( 2) ER duct expansion ratio, outlet to inlet width H step height x distance downstream of step X* normalized distance, x/x r Re o Reynolds number based on inlet boundary-layer momentum thickness, and Ure r Re n

Reynolds number based on H and Ur, r S* coefficient in Eq. ( 3), (1 -C e ,a.