A boundary layer developing in an increasingly adverse pressure gradient

Abstract

This paper deals with a survey of mean flow and fluctuating quantities in a turbulent boundary layer developing on a smooth wall in a pressure domain P(x), where both dP/dx and d2P/dx2 are positive (increasingly adverse). The two-dimensional nature of the flow field was checked by momentum balance, as well as velocity traverses either side of the working section centre-line. Using the integrated form of the momentum integral equation, it was found that the skinfriction term and the summed momentum and pressure terms differed by at most 19%; but for the majority of measuring points they differed by less than 14%. The off-centre-line velocity profiles were indistinguishable from those taken on the centre-line. The flow field was also surveyed for fluctuating components $(\overline{u^2_1})^{\frac{1}{2}}, (\overline{u^2_2})^{\frac{1}{2}}, (\overline{u^2_3})^{\frac{1}{2}}$, and $\overline{u_1u_2}$, as well as for u1 spectra. Wherever possible, the results were compared with existing models of boundary-layer development. These comparisons indicated that the only all-embracing model for boundary-layer development is the law of the wall.

An experimental investigation of wall pressure fluctuations beneath non-equilibrium turbulent flows

“…Bradshaw (1971) suggested that data presentation in this format might be advantageous since it displays the relative contribution each frequency range makes to the overall mean-square value since w4P(w)d(logw)=•w()dw. Samuel and Joubert (1974), as well as Bullock et al (1978), presented velocity spectra in this format to emphasize the differences between measurements at different wall locations. Strickland and Simpson (1975) state that the peak in the first-moment spectral density of the streamwise velocity fluctuations occur due to a statistically periodic turbulence phenomena which they argue is the "bursting" phenomena that occurs near the wall.…”

Turbulence model investigations on the boundary layer flow with adverse pressure gradients

“…For instance, as the magnitude of APG increases, the mean velocity profile develops a large wake region and the turbulent kinetic energy decreases in the near-wall region. Therefore, it is really difficult to predict flow with large APG by using common industrial methods such as RANS (Samuel and Joubert, 1974).…”

Effects of Surface Roughness on Turbulent Transonic Flow Over Circular Arc Bumps in a Channel

“…The effect of step applications of curvature on a turbulent boundary layer is now reasonably well known due to the works of So and Mellor (1973), Gillis and Johnston (1983), and Hoffmann, Muck and Bradshaw (1985), among others. A step variation in streamwise pressure gradient has also been the subject of a number of investigations of which the works of Bradshaw and Galea (1967) and Samuel and Joubert (1974) can be mentioned. Perturbations in both pressure gradient and curvature show that the combined influence of external perturbations is not a simple summation of their separate effects as reported by Smits, Eaton and Bradshaw (1979) and Smits and Wood (1985).…”