The Influence of Free-Stream Turbulence on an Axisymmetric Turbulent Boundary Layer in, and Relaxing from, an Adverse Pressure Gradient

The Influence of Periodic Excitation on a Turbulent Separation Bubble

“…v (x, y, z, t) =ṽ(y)e i(αx+βz−ωt) (12) where α and β denote streamwise and spanwise wave numbers, respectively and k 2 = α 2 + β 2 . The results from the Orr-Sommerfeld equations are only valid as long as the perturbations are small enough and the length scale of the perturbations is smaller than the variation of the mean flow in horizontal direction due to the assumption of parallel mean flow which is made in the derivation.…”

“…In comparison with the earlier simulations the flow had a stronger and larger recirculation region. Recently, Manhardt and Friedrich [18] carried out a DNS of the separated turbulent boundary layer comparable to the experiment of Kalter and Fernholz [12] but at half the Reynolds number of the experiment. They found that the shape and the dynamics of the separation bubble are governed by the large scale vortices reaching from the wall into the shear layer above it.…”

Large Eddy Simulation of a Separating Turbulent Boundary Layer

“…The Reynolds number based on the momentum thickness at the inlet is Re θ = 870. The separation and reattachment positions are extremely sensitive to flow conditions such as inflow turbulence level which comes from the relatively slow separation process due to a mild adverse pressure gradient [2]. The separation bubble is extremely thin and short, and is subjected to strong three-dimensional disturbances from the outer flow.…”

“…Experimental and numerical data are available for comparison. DNS data of Manhart [3] are available at the same Reynolds number and experimental data by Kalter and Fernholz [2] at a higher Reynolds number, Re = 1560. Both data are used for cross validation.…”