Three-dimensional unsteady laminar shock-wave/boundary layer interaction (original) (raw)

On the three-dimensionality of shock-wave/laminar bound-ary layer interaction

Abstract. Three-dimensional direct numerical simulation (DNS) of shock-wave/laminar boundary layer interaction (SWLBLI) is performed with for objective to show that a SWLBLI can exhibit self-sustained low frequency oscillations and a three-dimensional flow when the interaction is high. A linearized global stability analysis is carried out in order to find some characteristics observed in the DNS.

Analysis of unsteady behavior in shockwave turbulent boundary layer interaction

The unsteady behavior in shockwave turbulent boundary layer interaction is investi- gated by analyzing results from a LES of a supersonic turbulent boundary layer over a compression-expansion ramp. The interaction leads to a very-low-frequency motion near the foot of the shock, with a characteristic frequency that is three orders of magnitude lower than the typical frequency of the incoming boundary layer. Wall pressure data are first analyzed by means of Fourier analysis, highlighting the low-frequency phenomenon in the interaction region. Furthermore, the flow dynamics are analyzed by a dynamic mode decomposition which shows the presence of a low-frequency mode associated with the pulsation of the separation bubble and accompanied by a forward-backward motion of the shock.

Analysis of unsteady behaviour in shockwave turbulent boundary layer interaction

Journal of Fluid Mechanics, 2012

The unsteady behaviour in shockwave turbulent boundary layer interaction is investigated by analysing results from a large eddy simulation of a supersonic turbulent boundary layer over a compression-expansion ramp. The interaction leads to a very-low-frequency motion near the foot of the shock, with a characteristic frequency that is three orders of magnitude lower than the typical frequency of the incoming boundary layer. Wall pressure data are first analysed by means of Fourier analysis, highlighting the low-frequency phenomenon in the interaction region. Furthermore, the flow dynamics are analysed by a dynamic mode decomposition which shows the presence of a low-frequency mode associated with the pulsation of the separation bubble and accompanied by a forward-backward motion of the shock.

Some Advances in Research of Shock Wave Turbulent Boundary Layer Interactions

A critical analysis of some recent experimental and computational research of 2-D and 3-D shock wave/turbulent boundary layer interaction (SWTBLI) is carried out. The specific stages of turbulent boundary layer separation development in a vicinity of compression ramps, forward-and backwardfacing steps, one-and double-fin configurations are considered. The flowfield topology and principal physical processes are analyzed and specified for different cases of SWTBLI. The examples of modern numerical modeling on a basis of the Reynolds-averaged Navier-Stokes equations with various turbulence models as well as Direct Numerical Simulation (DNS) and Large Eddy Simulation (LES) are demonstrated and compared. The perspectives and problems of future SWTBLI studies are discussed.

Unsteadiness in shock wave boundary layer interactions with separation

Aerospace Science and Technology, 2006

Shock/turbulent boundary-layer interactions produce generally unsteadiness of the shock system. This phenomenon is reviewed and analyzed, by evaluating the results of various experiments; in particular results in the case of a shock reflection are presented. It appears that the frequency of the fluctuations produced by the shock motion are much lower than the characteristic frequencies of turbulence in the incoming

Unsteady effects of strong shock-wave/boundary-layer interaction at high Reynolds number

We analyse the low-frequency dynamics of a high Reynolds number impinging shock-wave/turbulent boundary-layer interaction (SWBLI) with strong mean-flow separation. The flow configuration for our grid-converged large-eddy simulations (LES) reproduces recent experiments for the interaction of a Mach 3 turbulent boundary layer with an impinging shock that nominally deflects the incoming flow by 19.6 •. The Reynolds number based on the incoming boundary-layer thickness of Re δ 0 ≈ 203 × 10 3 is considerably higher than in previous LES studies. The very long integration time of 3805δ 0 /U 0 allows for an accurate analysis of low-frequency unsteady effects. Experimental wall-pressure measurements are in good agreement with the LES data. Both datasets exhibit the distinct plateau within the separated-flow region of a strong SWBLI. The filtered three-dimensional flow field shows clear evidence of counter-rotating streamwise vortices originating in the proximity of the bubble apex. Contrary to previous numerical results on compression ramp configurations, these Görtler-like vortices are not fixed at a specific spanwise position, but rather undergo a slow motion coupled to the separation-bubble dynamics. Consistent with experimental data, power spectral densities (PSD) of wall-pressure probes exhibit a broadband and very energetic low-frequency component associated with the separation-shock unsteadiness. Sparsity-promoting dynamic mode decompositions (SPDMD) for both spanwise-averaged data and wall-plane snapshots yield a classical and well-known low-frequency breathing mode of the separation bubble, as well as a medium-frequency shedding mode responsible for reflected and reattachment shock corrugation. SPDMD of the two-dimensional skin-friction coefficient further identifies streamwise streaks at low frequencies that cause large-scale flapping of the reattachment line. The PSD and SPDMD results of our impinging SWBLI support the theory that an intrinsic mechanism of the interaction zone is responsible for the low-frequency unsteadiness, in which Görtler-like vortices might be seen as a continuous (coherent) forcing for strong SWBLI.