Shock wave

About: Shock wave is a research topic. Over the lifetime, 36184 publications have been published within this topic receiving 635848 citations. The topic is also known as: Shock waves & shockwave.

Mach 5 bow shock control by a nanosecond pulse surface dielectric barrier discharge

Abstract: Bow shock perturbations in a Mach 5 air flow, produced by low-temperature, nanosecond pulse, and surface dielectric barrier discharge (DBD), are detected by phase-locked schlieren imaging. A diffuse nanosecond pulse discharge is generated in a DBD plasma actuator on a surface of a cylinder model placed in air flow in a small scale blow-down supersonic wind tunnel. Discharge energy coupled to the actuator is 7.3–7.8 mJ/pulse. Plasma temperature inferred from nitrogen emission spectra is a few tens of degrees higher than flow stagnation temperature, T = 340 ± 30 K. Phase-locked Schlieren images are used to detect compression waves generated by individual nanosecond discharge pulses near the actuator surface. The compression wave propagates upstream toward the baseline bow shock standing in front of the cylinder model. Interaction of the compression wave and the bow shock causes its displacement in the upstream direction, increasing shock stand-off distance by up to 25%. The compression wave speed behind the...

The effects of target compliance on liquid drop impact

Abstract: When a liquid drop impacts a solid surface, the contact periphery at first expands more quickly than the compression wavefronts in either liquid or solid. The liquid behind the shock envelope is compressed and high pressures of order ρCV result, where ρ is the density of the liquid at ambient pressure, C the shock velocity in the liquid, and V the impact velocity. At a later stage, the shock envelope overtakes the contact periphery and a jetting motion, which releases the high pressures, commences. The magnitude and duration of the high pressures are critical in explaining the damage mechanisms and erosion processes caused by liquid impact. The experiments described in this paper use the two‐dimensional gel and photographic techniques developed for visualizing the shocks, recording the onset of jetting, and measuring jet velocities. This particular study is primarily concerned with the effect of target compliance on the early stages of impact. It is shown that the greater the target compliance, the longer...

Maximum Energy of Cosmic-Ray Particles Accelerated by Supernova Remnant Shocks in Stellar Wind Cavities

Abstract: Diffusive shock acceleration, balanced by adiabatic losses, leads readily to particle energies of more than 10 to the 15th eV in the case of a supernova shock freely expanding into a stellar wind cavity. This process accelerates particles early on out of stellar wind material which is often enriched in certain elements (isotopes), and may thus contribute to explain elemental and isotopic anomalies in the cosmic rays. It is speculated that the same process may produce particle energies up to 10 to the 19th eV in the case of a supernova explosion in a compact binary star. 22 references.

Interplanetary flow systems associated with cosmic ray modulation in 1977 - 1980

Abstract: The hydromagnetic flow configurations associated with cosmic ray modulation in 1977 to 1980 were determined using solar wind plasma and magnetic field data from Voyagers 1 and 2 and Helios 1. The modulation was related to two types of large scale systems of flows: one containing a number of transients such as shocks, post shock flows and magnetic clouds; the other consisting primarily of a series of quasi-stationary flows following interaction regions containing a stream interface and often bounded by a forward reverse shock pair. Each of the three major episodes of cosmic ray modulation was characterized by the passage of the system of transient flows. Plateaus in the cosmic ray intensity time profile were associated with the passage of systems of corotating streams.

Transient Excitation of an Elastic Half Space by a Point Load Traveling on the Surface

Abstract: The propagation of transient waves in an elastic half-space excited by a traveling normal point load is investigated. The load is suddenly applied and then it moves rectilinearly at a constant speed along the free surface. The displacements are computed for all points of the half-space as well as for all load speeds. The disturbance is analyzed by using multi-integral transforms and an inversion scheme based on the well-known Cagniard technique. This reduces the displacements to single integral and algebraic contributions, each of which is identified as the disturbance behind a specific wave front. The same solution is valid for all load speeds, even though the wave front geometry varies greatly, depending on the speed of the load relative to the body wave speeds. Moreover, the surface displacements are obtained from the interior ones, but only after the Rayleigh waves are computed by a separate calculation. Then, by taking advantage of the form of the exact solution, wave front expansions and Rayleigh wave approximations are computed for all load speeds. Several other analytical results are obtained for restricted values of the load speed. In particular, when it exceeds both of the body wave speeds the steady-state displacement field is separated from the transient one and reduced to algebraic form. Also, for the limit case of zero load speed a new representation of the interior displacements for Lamb's point load problem is displayed in terms of single integrals.