Shock wave boundary layer interactions are common to both supersonic and hypersonic inlet flows. Wall-resolved implicit large-eddy simulations of a canonical Mach 2.5 axisymmetric shock interaction experiment at Glenn Research Center were carried out. A conical was generated with centerbodies 16 deg half-angle cone. The centerbody radii 9.2% 14.7% the test section diameter. interacted turbulent...

The motivation behind this paper comes from the large-scale coherence that has been recently reported in the near-wall and logarithmic regions of wall-bounded turbulent flows. Associated with these are inclined vortical structures that populate the near-wall region. Most often these inclined structures have been inferred as hairpin shaped vortices that have been observed experimentally and evid...

We investigate energy amplification in parallel channel flows, where background noise is modeled as stochastic excitation of the linearized Navier–Stokes equations. We show analytically that the energy of three-dimensional streamwise-constant disturbances achieves O(R) amplification. Our basic technical tools are explicit analytical calculations of the traces of solutions of operator Lyapunov e...

The coherent structures in turbulent boundary layers (TBLs) subjected to adverse pressure gradients (APGs) were investigated by analyzing a database of direct numerical simulations. The equilibrium adverse pressure gradient flows were established by using a power law free-stream distribution. The population trends of the spanwise vortices show that the outer regions of the APG TBLs are densely ...

Direct numerical simulation of a turbulent channel flow at Reτ 2320 was performed in order to examine the flow statistics, and the relationship between the near-wall and outer-layer structures. The number of the total grid points is about 16 billions, and the effective computational speed is about 5.5 TFLOPS by using 2048 CPUs and 4 TB main memory on the Earth Simulator. The mean velocity profi...

A direct numerical simulation (DNS) of a channel flow with one curved surface was performed at moderate Reynolds number (Reτ = 395 at the inlet). The adverse pressure gradient was obtained by a wall curvature through a mathematical mapping from physical coordinates to Cartesian ones. The code, using spectral spanwise and normal discretization, combines the advantage of a good accuracy with a fa...

Direct numerical simulation is used to investigate the nature and behaviour of steady spanwise flow modulations excited internally in the Blasius boundary layer, primarily for a Reynolds number based on the displacement thickness ( Æ ) greater than 1,600. Both types of disturbances known – -/streak-/Klebanoff modes or longitudinal vortex modes – exhibit a periodic spanwise variation, but the -m...

Direct numerical simulations are employed to investigate the effects of discrete suction orifices at the wall on the disturbance evolution in laminar three-dimensional boundary-layer flows with favourable pressure gradient. Suction panels with many suction orifices can excite unstable crossflow (CF) modes even if the orifice spacing is smaller than the chordwise/spanwise wavelengths of unstable...

Proper orthogonal decomposition (POD) is applied to the direct numerical simulation (DNS) of a turbulent boundary layer performed by Wu & Moin (2010), and the resulting POD modes of various scales are examined. The modes include structures resembling those observed in instantaneous flow fields, such as large-scale motions of streamwise velocity with ramp-like wall-normal growth. Other modes cor...

Direct numerical simulation of turbulent channel flow over a compliant surface has been performed to evaluate the friction drag reduction effect. It is found that a slight drag reduction is observed over a compliant surface. This observation indicates that drag reduction is possible using a compliant surface that is deformed passively by wall pressure fluctuation. A small wall displacement and ...