The Scattering of Shock Waves by Cylindrical Cavities in Liquids and Solids

1971 ◽  
Vol 38 (1) ◽  
pp. 190-196 ◽  
Author(s):  
E. Y. Harper
Keyword(s):  
Shock Wave ◽  
Asymptotic Expansion ◽  
Shielding Effect ◽  
Inviscid Fluid ◽  
Shadow Region ◽  
Shock Diffraction ◽  
Fluid Medium ◽  
Acoustic Shock Wave ◽  
Cylindrical Cavities ◽  
Logarithmic Decay

The scattering of a plane acoustic shock wave by a cylindrical cavity in an inviscid fluid medium is calculated numerically and compared with a recently obtained asymptotic expansion. In contrast to the scattering by a rigid cylinder, the cavity displays a distinctive shielding effect in the shadow region characterized by a peak exitation and an inverse logarithmic decay. Experimental results are presented which indicate a strong counterpart in plastic shock diffraction.

scholarly journals Non-linear weak shock diffraction

1968 ◽  
Vol 8 (4) ◽  
pp. 737-754 ◽  
Author(s):  
N. J. De Mestre
Keyword(s):  
Shock Wave ◽  
Shock Front ◽  
Weak Shock ◽  
Weak Shock Wave ◽  
Shadow Region ◽  
Ray Theory ◽  
Perturbation Expansions ◽  
Shock Diffraction ◽  
Non Linear ◽  
Flow Variables

AbstractPerturbation expansions are sought for the flow variables associated with the diffraction of a plane weak shock wave around convex-angled corners in a polytropic, inviscid, thermally-nonconducting gas. Lighthill's method of strained co-ordinates [4] produces a uniformly valid expansion for most of the diffracted front, while the remainder of this front is treated by a modification of the shock-ray theory of Whitham [6]. The solutions from these approaches are patched just inside the ‘shadow’ region yielding a plausible description of the entire diffracted shock front.

Accelerated tattoo removal with acoustic shock wave therapy in conjunction with a picosecond laser

2018 ◽  
Vol 50 (9) ◽  
pp. 890-892 ◽  
Author(s):  
Ramya Vangipuram ◽  
Selina S. Hamill ◽  
Paul M. Friedman
Keyword(s):  
Shock Wave ◽  
Picosecond Laser ◽  
Shock Wave Therapy ◽  
Tattoo Removal ◽  
Acoustic Shock Wave

On the theory of a shock wave driven by a corrugated piston in a non-ideal fluid

2011 ◽  
Vol 691 ◽  
pp. 146-164 ◽  
Author(s):  
J. W. Bates
Keyword(s):  
Shock Wave ◽  
Ideal Gas ◽  
Mathematical Framework ◽  
Fluid Medium ◽  
Temporal Behaviour ◽  
Shock Stability ◽  
Linear Perturbations ◽  
Ripple Amplitude ◽  
The Stability ◽  
Appl Math

AbstractIn the context of an Eulerian fluid description, we investigate the dynamics of a shock wave that is driven by the steady impulsively initiated motion of a two-dimensional planar piston with small corrugations superimposed on its surface. This problem was originally solved by Freeman (Proc. Royal Soc. A, vol. 228, 1955, pp. 341–362), who showed that piston-driven shocks are unconditionally stable when the fluid medium through which they propagate is an ideal gas. Here, we generalize Freeman’s mathematical framework to account for a fluid characterized by an arbitrary equation of state. We find that a sufficient condition for shock stability is $\ensuremath{-} 1\lt h\lt {h}_{c} $, where $h$ is the D’yakov parameter and ${h}_{c} $ is a critical value less than unity. For values of $h$ within this range, linear perturbations imparted to the front by the piston at time $t= 0$ attenuate asymptotically as ${t}^{\ensuremath{-} 3/ 2} $. Outside of this range, the temporal behaviour of perturbations is more difficult to determine and further analysis is required to assess the stability of a shock front under such circumstances. As a benchmark of the main conclusions of this paper, we compare our generalized expression for the linearized shock-ripple amplitude with an independent Bessel-series solution derived by Zaidel’ (J. Appl. Math. Mech., vol. 24, 1960, pp. 316–327) and find excellent agreement.

Bubble collapse and the initiation of explosion

1991 ◽  
Vol 435 (1894) ◽  
pp. 423-435 ◽  
Keyword(s):  
Shock Wave ◽  
Plane Wave ◽  
High Speed ◽  
Bubble Collapse ◽  
Thin Sheets ◽  
Subsequent Reaction ◽  
Emulsion Explosive ◽  
Wave Generator ◽  
Ignition Mechanism ◽  
Cylindrical Cavities

Experiments were conducted to investigate the initiation of an emulsion explosive containing cavities. Cylindrical cavities were created in thin sheets of either gelatine or an ammonium nitrate/sodium nitrate emulsion confined between transparent blocks. Shocks were launched into the sheets with either a flier-plate or an explosive plane-wave generator so as to collapse the cavities asymmetrically. The closure of the cavities and subsequent reaction in the explosive was photographed by using high- speed framing cameras. The collapse of the cavity proceeded in several stages. First, a high-speed jet was formed which crossed the cavity and hit the downstream wall sending out a shock wave into the surrounding material. Secondly, gas within the cavity was heated by rapid compression achieving temperatures sufficient to lead to gas luminescence. Finally, the jet penetrated the downstream wall to form a pair of vortices which travelled downstream with the flow. When such a cavity collapsed in an explosive, a reaction was observed to start in the vapour contained within the cavity and in the material around the heated gas. The ignition of material at the point at which the jet hit was found to be the principal ignition mechanism.

Vibration of Elastic Beams in the Presence of an Inviscid Fluid Medium

2014 ◽  
Vol 14 (06) ◽  
pp. 1450022 ◽  
Author(s):  
Helnaz Soltani ◽  
Gregory S. Payette ◽  
J. N. Reddy
Keyword(s):  
Structural Response ◽  
Practical Significance ◽  
Element Formulation ◽  
Physical Interaction ◽  
Inviscid Fluid ◽  
Fluid Medium ◽  
Vast Number ◽  
Inviscid Incompressible Fluid ◽  
Vortex Induced Vibrations ◽  
Flow Through

The physical interaction of fluids and solids is of practical significance in engineering (e.g. flutter of aerodynamic structures, vortex induced vibrations of sub-sea pipelines and risers, inflatable dams, parachute dynamics and blood flow through arteries). In this paper, a finite element formulation is developed for determining the vibration characteristics of beams in contact with inviscid incompressible fluid. The classical, first-order and third-order shear deformation beam theories are used to model the structural response. Numerical results for vibration frequencies are presented showing the parametric effect of thickness and immersion depth on the frequency response. The results indicate that the presence of fluid interaction has significant effect on the dynamic response. The formulation presented herein is also applicable to a vast number of vibration problems related to beams under a variety of excitations.

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