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Oblique shock

About: Oblique shock is a research topic. Over the lifetime, 6551 publications have been published within this topic receiving 119823 citations.


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TL;DR: In this paper, the authors investigated the interaction between a plane entropy wave of arbitrary orientation and a plane oblique shock of infinite extent and found that, in the perturbed flow field downstream of the shock, three kinds of disturbances are present:namety, an entropy mode, a vorticity mode, and a sound mode.
Abstract: The problem of the interaction between a plane entropy wave of arbitrary orientation and a plane oblique shock of infinite extent is investigated. As a result of the interaction, it is found that, in the perturbed flow field downstream of the shock, three kinds of disturbances are present—namety, an entropy mode, a vorticity mode, and a sound mode. The nature of the sound wave generated depends on the orientation of the upstream disturbance. Within certain orientations of the upstream disturbance, the sound waves generated downstream attenuate. Beyond these orientations, the sound waves generated have constant amplitudes. When the downstream sound waves are not attenuated, there is no phase shift in the entropy disturbance across the shock; when the downstream sound waves are attenuated, a phase shift occurs in the entropy disturbance across the shock. An illustrative example is given for the interaction between a plane normal shock and a sinusoidal entropy wave. At a given shock strength the amplitudes of the shock displacement and the downstream disturbances generated are plotted as functions of the orientation of the upstream disturbance.

63 citations

Journal ArticleDOI
TL;DR: In this paper, a largeeddy simulation-based study is presented and focuses on different unsteadiness-source features in a Mach 2.3 shock reflection with separation, where the sources of unstiffiness are localized and the path taken by disturbance as it spreads out to the whole field is defined.
Abstract: A large-eddy simulation-based study is presented and focuses on different unsteadiness-source features in a Mach 2.3 shock reflection with separation. The sources of unsteadiness are localized and the path taken by disturbance as it spreads out to the whole field is defined. It is shown that the phenomena arising inside the recirculation bubble govern the whole interaction, at both low and intermediate frequencies. Indeed, the shock motion appears to mirror phenomena found in the separated zone. Moreover, features of separated-flow unsteadiness bear some resemblance to those occurring in incompressible flows. An equivalent inviscid scheme of the unsteady interaction is established in order to describe the whole shock-system unsteadiness at low and intermediate frequencies and the downstream unsteady-pressure field.

63 citations

Journal ArticleDOI
TL;DR: In this paper, the authors focused on interactions of a normal shock with grid-generated turbulence in a shock tube and found that significant amplification of turbulence has been found after the interaction which depends on the length scale of the incoming flow.
Abstract: Most of the previous work on turbulence amplification by shock wave interaction is limited to shock wave/boundary layer types of interactions where additional effects due to shock wave oscillation, streamline curvature, and flow separation complicate the understanding of the physics involved in this phenomenon. The present experimental study has focused on interactions of a normal shock with grid‐generated turbulence in a shock tube. The decaying turbulence behind the grid is characterized by a variation of length scales with downstream distance and is subjected to an interaction with the reflected shock traveling in the opposite direction. Considerable amplification of turbulence has been found after the interaction which depends on the length scale of the incoming flow. Spectral analysis has also indicated that large eddies are amplified more than small eddies during interactions with shock waves of the same strength.

63 citations

Journal ArticleDOI
TL;DR: In this paper, it was shown that the distance between the terminal shock and the contact discontinuity is less than the heliocentric distance to the terminal shell, effectively eliminating magnetic field effects in the heliosheath as being dynamically important.
Abstract: Recent reports of remote detection of the heliospheric terminal shock place it near 50 AU. These conflict with standard models which, when combined with current data on the local interstellar medium, place the shock beyod 100 AU. Resolution of this discrepancy has led to hypotheses that invoke cosmic ray pressure, momentum exchange with interstellar neutrals, and magnetic field effects between the shock and the contact discontinuity dividing the solar wind from interstellar plasma. These hypotheses depend not only on properties of the interstellar medium, but also on the downstream three-dimensional flow between the shock and the contact discontinuity, in the region called the 'heliosheath'. The downstream flow field in the absence of magnetic fields is examined here under the assumptions that the flow everywhere outside the shock can be approximated as irrotational and incompressible. It is found, in particular, that the distance between the terminal shock and the contact discontinuity is less than the heliocentric distance to the terminal shock, effectively eliminating magnetic field effects in the heliosheath as being dynamically important.

63 citations

Journal ArticleDOI
TL;DR: In this paper, the complex flow features that arise from the impact of a shock wave on a concave cavity are determined by means of high-speed video photography, and two jets can be formed, one facing forward and the other backward, with the first one folding back on itself.
Abstract: The complex flow features that arise from the impact of a shock wave on a concave cavity are determined by means of high-speed video photography. Besides additional information on features that have previously been encountered in specific studies, such as those relating to shock wave reflection from a cylindrical wall and those associated with shock wave focusing, a number of new features become apparent when the interaction is studied over longer times using time-resolved imaging. The most notable of these new features occurs when two strong shear layers meet that have been generated earlier in the motion. Two jets can be formed, one facing forward and the other backward, with the first one folding back on itself. The shear layers themselves develop a Kelvin–Helmholtz instability which can be triggered by interaction with weak shear layers developed earlier in the motion. Movies are available with the online version of the paper.

62 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202369
2022142
2021106
202090
201992
2018102