Turbulent Flow Around a Bluff Rectangular Plate. Part I: Experimental Investigation

Abstract

Measurements are reported for the separted reattaching flow around a long rectangular plate placed at zero incidence in a low-turbulence stream. This laboratory configuration, chosen for its geometric simplicity, exhibits all of the important features of two-dimensional flow separation with reattachment. Conventional hot-wire anemometry, pulsed-wire anemometry and pulsed-wire surface shear stress probes were used to measure the mean and fluctuating flow field at a Reynolds number, based on plate thickness, of 5 × 104. The separated shear layer appears to behave like a conventional mixing layer over the first half of the separation bubble, where it exhibits an approximately constant growth rate and a linear variation of characteristic frequencies and integral timescales. The characteristics of the shear layer in the second half of the bubble are radically altered by the unsteady reattachment process. Much higher turbulent intensities and lower growth rates are encountered there, and, in agreement with other reattaching flow studies, a low frequency motion can be detected.

Numerical study of transitional separated–reattached flow over surface‐mounted obstacles using large‐eddy simulation

“…The edge of the shear layer is defined as the locus of points where u rms /U 0 has a value of 2.5%. This definition is consistent with the experimental studies of Dijalali and Gartshore [35] and Cherry et al [36]. In the current case, few samples are collected to approximate the position of the edge and the centre of the shear layer prior to sample collection for the spectra analysis.…”

Effects of free-stream turbulence on a transitional separated–reattached flow over a flat plate with a sharp leading edge

“…It is worth pointing out that the experiment was carried out with very low free-stream turbulence level but at a higher Reynolds number (26,000) and the measured reattachment length was 5.05D. The mean bubble length is Reynolds number dependent as Cherry et al (1984) reported a measured value of around 4.9D for a Reynolds number of about 32,000 and Djilali and Gartshore (1991) measured a value of about 4.7D at a Reynolds number of 50,000. To facilitate comparisons the profiles are plotted as function of y/ x R at corresponding values of x/x R , i.e., comparisons are made at the same non-dimensionalised location (x/x R ) but not at the same geometric location (x).…”

Effects of free-stream turbulence on large-scale coherent structures of separated boundary layer transition

“…The experiment was carried out with very low FST level but at much higher Reynolds number (26 000) and the measured reattachment length was about 5D. The mean reattachment length is Reynolds number dependent as Djilali and Gartshore [22] reported a value of about 4:7D at a much higher Reynolds number (50 000). Numerically, several factors could a ect the predicted bubble length such as subgridscale models, which is demonstrated by Suksangpanomrung et al [23] using three di erent subgrid-scale models.…”