Oblique shock

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

Spurious Numerical Oscillations in Simulation of Supersonic Flows Using Shock-Capturing Schemes

Abstract: The numerical simulation of transitional and turbulent e ows in supersonic boundary layers often involves a physical process of a shock ‐disturbance wave interaction in complex multidimensional e owe elds. For such simulations, it is required that there be a high order of accuracy in capturing the shock waves without spurious numerical disturbances. Evaluation of the numerical oscillations generated behind a stationary bow shock by using high-order shock-capturing schemes in computing multidimensional steady supersonic e ow over a circular cylinderiscarriedout.Thenumerical methodsthatarestudied aretheTotalVariation Diminishing schemeand the Essentially Non-Oscillatory scheme. Although the general aerodynamic properties are appropriately captured by the shock-capturing schemes, it is shown that there are numerical oscillations in the gradients of the aerodynamic propertiesin the steady e owe eld behind the bow shock, such asfor vorticity. Thesespurious numerical oscillations in the e owe eld solution may hinder any attempt at tracking the propagation of physical disturbances behind the shock if unsteady simulations are carried out. They can be signie cant enough to pollute a e owe eld containing small physical disturbances. It is shown that the effects of grid ree nement do not reduce the oscillations but rather decreasetheir wavelength. It is also shown that, by roughly aligning the shock with the grid, the amplitude of these spurious oscillations can be reduced but not eliminated.

Three-dimensional hydrodynamic simulations of narrow-angle-tail radio sources. I: The Begelman, Rees, and Blandford model

Abstract: Narrow-angle-tail radio sources have been explained by various authors as being the result of ram-pressure-induced bending of supersonic radio jets by a transonic crosswind. The details of the models differ, but their common element is the necessity of a supersonic jet and a crosswind. We have, therefore, made a computational study of the bending of light supersonic jets by a wind flowing normally to it using the highly accurate RIEMANN code run at the highest resolutions that are currently feasible. RIEMANN is a three-dimensional hydrocode that implements the piecewise parabolic method of Colella and Woodward

Shock Impingement Caused by Boundary-Layer Separation Ahead of Blunt Fins

Abstract: : High speed flow past a blunt protuberance on a surface results in a complex, three dimensional, inviscid-viscous interaction flow field. Characteristically, the interaction results in a separated flow region composed of horseshoe vortices near the surface, and a lambda-type shock pattern in the plane of symmetry ahead of the protuberance. The shock wave emanating from the separated flow region impinges on the bow shock ahead of the protuberance and causes intense heating and high pressures locally on the protuberance leading edge. The heating and pressure in this local area can be 10 times larger than the undisturbed stagnation line values; the amplification depends strongly on local flow conditions. Tests were conducted to examine and obtain a better understanding of these interaction flow fields; the most recent tests included detailed flow field surveys for Mach 3 flows ahead of blunt fins on a flat plate surface with turbulent boundary layers. (Author)

An Implementation of a Grid-Independent Upwind Scheme for the Euler Equations

Abstract: A scheme for the twedimensional Euler equations that uses flow parameters to determine the direction for upwind-differencing is described. This approach reduces the grid-dependence of conventional schemes. Upwinding at the local flow angle and the local pressure-gradient angle is tested. The upwindbiased fluxes are calculated with Roe's approximate Riemann solver. A centered flux is used for the component normal to the upwinding direction. Results for a first-order scheme show significant improvement over conventional grid-aligned upwinding. Specifically, oblique shock waves are less diffused. Preliminary results for a second-order scheme are also included.