Some new aspects of the shock-wave/boundary-layer interaction in compression-ramp flows

Abstract

The present study of the pressure fluctuations in the interaction region oif a two-dimensionals compression flow established that the frequency of the shock-wave unsteadiness is of the same order as the bursting frequency of the upstream boundary layer and that this frequency is independent of the downstream separated flow. The conditional-sampling technique developed herein is capable of separating phenomena due to shock-wave oscillations from those due to transport phenomena of turbulence. The results show that turbulence as inferred from wall-pressure fluctuations may be significantly amplified approaching the shock.

Large-Eddy Simulation of the Shock/Turbulence Interaction

“…Although we keep a scalar dissipation model, we take the value k (2) equal to 1.5 which can be considered as large. As noticed in [43], a typical value around 0.5 gives a global scheme close to a first-order upwind scheme in the case of the scalar equation provided k (2) is equal to 0.5. For the presented test case, values are typically around 0.15, which leads to k (2) ≈ 0.075 for standard k (2) = 0.5.…”

“…As noticed in [43], a typical value around 0.5 gives a global scheme close to a first-order upwind scheme in the case of the scalar equation provided k (2) is equal to 0.5. For the presented test case, values are typically around 0.15, which leads to k (2) ≈ 0.075 for standard k (2) = 0.5. This produces good results for stationary problems (RANS approach) but can lead to spurious oscillations in the shock region for the unsteady case.…”

“…k (2) and k (4) are real numbers fixing the amount of diffusion brought up by the secondand fourth-order dissipative operators. R j+1/2 is the spectral radius of the jacobian matrix ∂ F/∂U at the cell face j + 1/2, measuring the anisotropic scaling factor of Swanson and Turkel [43].…”

“…(8) and (9), and setting the number k (2) to a value switching from central to first-order upwind scheme when second-order dissipation is activated. Although we keep a scalar dissipation model, we take the value k (2) equal to 1.5 which can be considered as large.…”

“…Many studies and results are available on this subject, extending from experimental ( [1][2][3] for interaction of turbulent boundary layer and shock) to theoretical [4,5] and numerical fields [6][7][8][9]. As underlined in Lee et al [6], the general finding is that both shock and turbulence are modified during their interaction: the shock is corrugated, depending on the level of turbulence, whereas turbulence intensities and Reynolds stresses are amplified across the shock wave.…”